microprocessor and microcontroller 8086 /8085

Case Study: Intel
Processors
Slide 2

Microproce
ssor
First Generation
Between 1971 – 1973
PMOS technology, non compatible with TTL
4 bit processors  16 pins
8 and 16 bit processors  40 pins
Due to limitations of pins, signals are
multiplexed
Second Generation
During 1973
NMOS technology  Faster speed, Higher
density, Compatible with TTL
4 / 8/ 16 bit processors  40 pins
Ability to address large memory spaces
and I/O ports
Greater number of levels of subroutine
nesting
Better interrupt handling capabilities
Intel 8085 (8 bit processor)
Third Generation
During 1978
HMOS technology  Faster speed, Higher
packing density
16 bit processors  40/ 48/ 64 pins
Easier to program
Dynamically relatable programs
Processor has multiply/ divide arithmetic
hardware
More powerful interrupt handling
capabilities
Flexible I/O port addressing
Intel 8086 (16 bit processor)
Fourth Generation
During 1980s
Low power version of HMOS technology
(HCMOS)
32 bit processors
Physical memory space 224 bytes = 16 Mb
Virtual memory space 240 bytes = 1 Tb
Floating point hardware
Supports increased number of addressing
modes
Intel 80386
Fifth Generation Pentium
3

Overview
8086 Microprocessor
First 16- bit processor released by
INTEL in the year 1978
Originally HMOS, now manufactured
using HMOS III technique
Approximately 29, 000 transistors, 40
pin DIP, 5V supply
Does not have internal clock; external
asymmetric clock source with 33%
duty cycle
20-bit address to access memory  can
address up to 220 = 1 megabytes of
memory space.
Addressable memory space is
organized in to two banks of 512 kb
each; Even (or lower) bank and Odd (or
higher) bank. Address line A0 is used to
select even bank and control signal 𝐁𝐇𝐄
is used to access odd bank
Uses a separate 16 bit address for I/O
mapped devices  can generate 216 =
64 k addresses.
Operates in two modes: minimum mode
and maximum mode, decided by the
signal at MN and 𝐌𝐗 pins.
4

Pins and Signals
8086 Microprocessor
5
Common signals
AD0-AD15 (Bidirectional)
Address/Data bus
Low order address bus; these are
multiplexed with data.
When AD lines are used to transmit
memory address the symbol A is used
instead of AD, for example A0-A15.
When data are transmitted over AD lines
the symbol D is used in place of AD, for
example D0-D7, D8-D15 or D0-D15.
A16/S3, A17/S4, A18/S5, A19/S6
High order address bus. These are
multiplexed with status signals

Pins and Signals
8086 Microprocessor
6
Common signals
BHE (Active Low)/S7 (Output)
Bus High Enable/Status
It is used to enable data onto the most
significant half of data bus, D8-D15. 8-bit
device connected to upper half of the
data bus use BHE (Active Low) signal. It
is multiplexed with status signal S7.
MN/ MX
MINIMUM / MAXIMUM
This pin signal indicates what mode the
processor is to operate in.
RD (Read) (Active Low)
The signal is used for read operation.
It is an output signal.
It is active when low.

Pins and Signals
8086 Microprocessor
7
Common signals
TEST
𝐓𝐄𝐒𝐓 input is tested by the ‘WAIT’
instruction.
8086 will enter a wait state after
execution of the WAIT instruction and
will resume execution only when the
𝐓𝐄𝐒𝐓 is made low by an active hardware.
This is used to synchronize an external
activity to the processor internal
operation.
READY
This is the acknowledgement from the
slow device or memory that they have
completed the data transfer.
The signal made available by the devices
is synchronized by the 8284A clock
generator to provide ready input to the
8086.
The signal is active high.

Pins and Signals
8086 Microprocessor
8
Common signals
RESET (Input)
Causes the processor to immediately
terminate its present activity.
The signal must be active HIGH for at
least four clock cycles.
CLK
The clock input provides the basic timing
for processor operation and bus control
activity. Its an asymmetric square wave
with 33% duty cycle.
INTR Interrupt Request
This is a triggered input. This is sampled
during the last clock cycles of each
instruction to determine the availability
of the request. If any interrupt request is
pending, the processor enters the
interrupt acknowledge cycle.
This signal is active high and internally
synchronized.

Pins and Signals
8086 Microprocessor
9
Min/ Max Pins
The 8086 microprocessor can work in two
modes of operations : Minimum mode and
Maximum mode.
In the minimum mode of operation the
microprocessor do not associate with any
co-processors and can not be used for
multiprocessor systems.
In the maximum mode the 8086 can work
in multi-processor or co-processor
configuration.
Minimum or maximum mode operations
are decided by the pin MN/ MX(Active low).
When this pin is high 8086 operates in
minimum mode otherwise it operates in
Maximum mode.

Pins and Signals
8086 Microprocessor
Pins 24 -31
For minimum mode operation, the MN/ 𝐌𝐗 is tied
to VCC (logic high)
8086 itself generates all the bus control signals
DT/ഥ
𝐑 (Data Transmit/ Receive) Output signal from the
processor to control the direction of data flow
through the data transceivers
𝐃𝐄𝐍 (Data Enable) Output signal from the processor
used as out put enable for the transceivers
ALE (Address Latch Enable) Used to demultiplex the
address and data lines using external latches
M/𝐈𝐎 Used to differentiate memory access and I/O
access. For memory reference instructions, it is
high. For IN and OUT instructions, it is low.
𝐖𝐑 Write control signal; asserted low Whenever
processor writes data to memory or I/O port
𝐈𝐍𝐓𝐀 (Interrupt Acknowledge) When the interrupt
request is accepted by the processor, the output is
low on this line.
10
Minimum mode signals

Pins and Signals
8086 Microprocessor
HOLD Input signal to the processor form the bus masters
as a request to grant the control of the bus.
Usually used by the DMA controller to get the
control of the bus.
HLDA (Hold Acknowledge) Acknowledge signal by the
processor to the bus master requesting the control
of the bus through HOLD.
The acknowledge is asserted high, when the
processor accepts HOLD.
11
Minimum mode signals
Pins 24 -31
For minimum mode operation, the MN/ 𝐌𝐗 is tied
to VCC (logic high)
8086 itself generates all the bus control signals

Pins and Signals
8086 Microprocessor
During maximum mode operation, the MN/ 𝐌𝐗 is
grounded (logic low)
Pins 24 -31 are reassigned
𝑺𝟎, 𝑺𝟏, 𝑺𝟐 Status signals; used by the 8086 bus controller to
generate bus timing and control signals. These are
decoded as shown.
12
Maximum mode signals

Pins and Signals
8086 Microprocessor
𝑸𝑺𝟎, 𝑸𝑺𝟏 (Queue Status) The processor provides the status
of queue in these lines.
The queue status can be used by external device to
track the internal status of the queue in 8086.
The output on QS0 and QS1 can be interpreted as
shown in the table.
13

Pins and Signals
8086 Microprocessor
𝐑𝐐/𝐆𝐓𝟎,
𝐑𝐐/𝐆𝐓𝟏
(Bus Request/ Bus Grant) These requests are used
by other local bus masters to force the processor
to release the local bus at the end of the
processor’s current bus cycle.
These pins are bidirectional.
The request on𝐆𝐓𝟎 will have higher priority than𝐆𝐓𝟏
14
𝐋𝐎𝐂𝐊 An output signal activated by the LOCK prefix
instruction.
Remains active until the completion of the
instruction prefixed by LOCK.
The 8086 output low on the 𝐋𝐎𝐂𝐊 pin while
executing an instruction prefixed by LOCK to
prevent other bus masters from gaining control of
the system bus.

8086 Microprocessor
Architecture
15

Architecture
8086 Microprocessor
16
Execution Unit (EU)
EU executes instructions that have
already been fetched by the BIU.
BIU and EU functions separately.
Bus Interface Unit (BIU)
BIU fetches instructions, reads data
from memory and I/O ports, writes
data to memory and I/ O ports.

Architecture
8086 Microprocessor
17
Dedicated Adder to generate
20 bit address
Four 16-bit segment
registers
Code Segment (CS)
Data Segment (DS)
Stack Segment (SS)
Extra Segment (ES)
Segment Registers >>

18
Architecture
8086 Microprocessor
Sl.No. Type Register width Name of register
1 General purpose register 16 bit AX, BX, CX, DX
8 bit AL, AH, BL, BH, CL, CH, DL, DH
2 Pointer register 16 bit SP, BP
3 Index register 16 bit SI, DI
4 Instruction Pointer 16 bit IP
5 Segment register 16 bit CS, DS, SS, ES
6 Flag (PSW) 16 bit Flag register
8086 registers
categorized
into 4 groups
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
OF DF IF TF SF ZF AF PF CF

19
Architecture
8086 Microprocessor
Register Name of the Register Special Function
AX 16-bit Accumulator Stores the 16-bit results of arithmetic and logic
operations
AL 8-bit Accumulator Stores the 8-bit results of arithmetic and logic
operations
BX Base register Used to hold base value in base addressing mode
to access memory data
CX Count Register Used to hold the count value in SHIFT, ROTATE
and LOOP instructions
DX Data Register Used to hold data for multiplication and division
operations
SP Stack Pointer Used to hold the offset address of top stack
memory
BP Base Pointer Used to hold the base value in base addressing
using SS register to access data from stack
memory
SI Source Index Used to hold index value of source operand (data)
for string instructions
DI Data Index Used to hold the index value of destination
operand (data) for string operations
Registers and Special Functions

Architecture
8086 Microprocessor
20
Segment
Registers
8086’s 1-megabyte
memory is divided
into segments of up
to 64K bytes each.
Programs obtain access
to code and data in the
segments by changing
the segment register
content to point to the
desired segments.
The 8086 can directly
address four segments
(256 K bytes within the 1
M byte of memory) at a
particular time.

Architecture
8086 Microprocessor
21
Segment
Registers
Code Segment Register
16-bit
CS contains the base or start of the current code segment;
IP contains the distance or offset from this address to the
next instruction byte to be fetched.
BIU computes the 20-bit physical address by logically
shifting the contents of CS 4-bits to the left and then
adding the 16-bit contents of IP.
That is, all instructions of a program are relative to the
contents of the CS register multiplied by 16 and then offset
is added provided by the IP.

Architecture
8086 Microprocessor
22
Segment
Registers
Data Segment Register
16-bit
Points to the current data segment; operands for most
instructions are fetched from this segment.
The 16-bit contents of the Source Index (SI) or
Destination Index (DI) or a 16-bit displacement are used
as offset for computing the 20-bit physical address.

Architecture
8086 Microprocessor
23
Segment
Registers
Stack Segment Register
16-bit
Points to the current stack.
The 20-bit physical stack address is calculated from the
Stack Segment (SS) and the Stack Pointer (SP) for stack
instructions such as PUSH and POP.
In based addressing mode, the 20-bit physical stack
address is calculated from the Stack segment (SS) and the
Base Pointer (BP).

Architecture
8086 Microprocessor
24
Segment
Registers
Extra Segment Register
16-bit
Points to the extra segment in which data (in excess of
64K pointed to by the DS) is stored.
String instructions use the ES and DI to determine the 20-
bit physical address for the destination.

Architecture
8086 Microprocessor
25
Segment
Registers
Instruction Pointer
16-bit
Always points to the next instruction to be executed within
the currently executing code segment.
So, this register contains the 16-bit offset address pointing
to the next instruction code within the 64Kb of the code
segment area.
Its content is automatically incremented as the execution
of the next instruction takes place.

Architecture
8086 Microprocessor
26
A group of First-In-First-
Out (FIFO) in which up to
6 bytes of instruction
code are pre fetched
from the memory ahead
of time.
This is done in order to
speed up the execution
by overlapping
instruction fetch with
execution.
This mechanism is known
as pipelining.
Instruction queue

Architecture
8086 Microprocessor
27
Some of the 16 bit registers can be
used as two 8 bit registers as :
AX can be used as AH and AL
BX can be used as BH and BL
CX can be used as CH and CL
DX can be used as DH and DL
Execution Unit (EU)
EU decodes and
executes instructions.
A decoder in the EU
control system
translates instructions.
16-bit ALU for
performing arithmetic
and logic operation
Four general purpose
registers(AX, BX, CX, DX);
Pointer registers (Stack
Pointer, Base Pointer);
and
Index registers (Source
Index, Destination Index)
each of 16-bits

Architecture
8086 Microprocessor
28
EU
Registers
Accumulator Register (AX)
Consists of two 8-bit registers AL and AH, which can be
combined together and used as a 16-bit register AX.
AL in this case contains the low order byte of the word,
and AH contains the high-order byte.
The I/O instructions use the AX or AL for inputting /
outputting 16 or 8 bit data to or from an I/O port.
Multiplication and Division instructions also use the AX or
AL.
Execution Unit (EU)

Architecture
8086 Microprocessor
29
EU
Registers
Base Register (BX)
Consists of two 8-bit registers BL and BH, which can be
combined together and used as a 16-bit register BX.
BL in this case contains the low-order byte of the word,
and BH contains the high-order byte.
This is the only general purpose register whose contents
can be used for addressing the 8086 memory.
All memory references utilizing this register content for
addressing use DS as the default segment register.
Execution Unit (EU)

Architecture
8086 Microprocessor
30
EU
Registers
Counter Register (CX)
Consists of two 8-bit registers CL and CH, which can be
combined together and used as a 16-bit register CX.
When combined, CL register contains the low order byte of
the word, and CH contains the high-order byte.
Instructions such as SHIFT, ROTATE and LOOP use the
contents of CX as a counter.
Execution Unit (EU)
Example:
The instruction LOOP START automatically decrements
CX by 1 without affecting flags and will check if [CX] =
0.
If it is zero, 8086 executes the next instruction;
otherwise the 8086 branches to the label START.

Architecture
8086 Microprocessor
31
EU
Registers
Data Register (DX)
Consists of two 8-bit registers DL and DH, which can be
combined together and used as a 16-bit register DX.
When combined, DL register contains the low order byte of
the word, and DH contains the high-order byte.
Used to hold the high 16-bit result (data) in 16 X 16
multiplication or the high 16-bit dividend (data) before a
32 ÷ 16 division and the 16-bit reminder after division.
Execution Unit (EU)

Architecture
8086 Microprocessor
32
EU
Registers
Stack Pointer (SP) and Base Pointer (BP)
SP and BP are used to access data in the stack segment.
SP is used as an offset from the current SS during
execution of instructions that involve the stack segment in
the external memory.
SP contents are automatically updated (incremented/
decremented) due to execution of a POP or PUSH
instruction.
BP contains an offset address in the current SS, which is
used by instructions utilizing the based addressing mode.
Execution Unit (EU)

Architecture
8086 Microprocessor
33
EU
Registers
Source Index (SI) and Destination Index (DI)
Used in indexed addressing.
Instructions that process data strings use the SI and DI
registers together with DS and ES respectively in order to
distinguish between the source and destination addresses.
Execution Unit (EU)

Architecture
8086 Microprocessor
34
EU
Registers
Source Index (SI) and Destination Index (DI)
Used in indexed addressing.
Instructions that process data strings use the SI and DI
registers together with DS and ES respectively in order to
distinguish between the source and destination addresses.
Execution Unit (EU)

Architecture
8086 Microprocessor
35
Flag Register
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
OF DF IF TF SF ZF AF PF CF
Carry Flag
This flag is set, when there is
a carry out of MSB in case of
addition or a borrow in case
of subtraction.
Parity Flag
This flag is set to 1, if the lower
byte of the result contains even
number of 1’s ; for odd number
of 1’s set to zero.
Auxiliary Carry Flag
This is set, if there is a carry from the
lowest nibble, i.e, bit three during
addition, or borrow for the lowest
nibble, i.e, bit three, during
subtraction.
Zero Flag
This flag is set, if the result of
the computation or comparison
performed by an instruction is
zero
Sign Flag
This flag is set, when the
result of any computation
is negative
Tarp Flag
If this flag is set, the processor
enters the single step execution
mode by generating internal
interrupts after the execution of
each instruction
Interrupt Flag
Causes the 8086 to recognize
external mask interrupts; clearing IF
disables these interrupts.
Direction Flag
This is used by string manipulation instructions. If this flag bit
is ‘0’, the string is processed beginning from the lowest
address to the highest address, i.e., auto incrementing mode.
Otherwise, the string is processed from the highest address
towards the lowest address, i.e., auto incrementing mode.
Over flow Flag
This flag is set, if an overflow occurs, i.e, if the result of a signed
operation is large enough to accommodate in a destination
register. The result is of more than 7-bits in size in case of 8-bit
signed operation and more than 15-bits in size in case of 16-bit
sign operations, then the overflow will be set.
Execution Unit (EU)

ADDRESSING MODES
&
Instruction set

Introduction
37
8086 Microprocessor
Program
A set of instructions written to solve
a problem.
Instruction
Directions which a microprocessor
follows to execute a task or part of a
task.
Computer language
High Level Low Level
Machine Language Assembly Language
 Binary bits  English Alphabets
 ‘Mnemonics’
 Assembler
Mnemonics  Machine
Language

Group I : Addressing modes for
register and immediate data
Group IV : Relative Addressing mode
Group V : Implied Addressing mode
Group III : Addressing modes for
I/O ports
Group II : Addressing modes for
memory data
Addressing Modes
40
8086 Microprocessor
Every instruction of a program has to operate on a data.
The different ways in which a source operand is denoted
in an instruction are known as addressing modes.
1. Register Addressing
2. Immediate Addressing
3. Direct Addressing
4. Register Indirect Addressing
5. Based Addressing
6. Indexed Addressing
7. Based Index Addressing
8. String Addressing
9. Direct I/O port Addressing
10. Indirect I/O port Addressing
11. Relative Addressing
12. Implied Addressing

Addressing Modes
41
8086 Microprocessor
5. Based Addressing
The instruction will specify the name of the
register which holds the data to be operated by
the instruction.
Example:
MOV CL, DH
The content of 8-bit register DH is moved to
another 8-bit register CL
(CL)  (DH)

Addressing Modes
42
8086 Microprocessor
5. Based Addressing
In immediate addressing mode, an 8-bit or 16-bit
data is specified as part of the instruction
Example:
MOV DL, 08H
The 8-bit data (08H) given in the instruction is
moved to DL
(DL)  08H
MOV AX, 0A9FH
The 16-bit data (0A9FH) given in the instruction is
moved to AX register
(AX)  0A9FH

Addressing Modes : Memory Access
44
8086 Microprocessor
20 Address lines  8086 can address up to
220 = 1M bytes of memory
However, the largest register is only 16 bits
Physical Address will have to be calculated
Physical Address : Actual address of a byte in
memory. i.e. the value which goes out onto the
address bus.
Memory Address represented in the form –
Seg : Offset (Eg - 89AB:F012)
Each time the processor wants to access
memory, it takes the contents of a segment
register, shifts it one hexadecimal place to the
left (same as multiplying by 1610), then add the
required offset to form the 20- bit address
89AB : F012  89AB  89AB0 (Paragraph to byte  89AB x 10 = 89AB0)
F012  0F012 (Offset is already in byte unit)
+ -------
98AC2 (The absolute address)
16 bytes of
contiguous memory

Addressing Modes
46
8086 Microprocessor
5. Based Addressing
Here, the effective address of the memory
location at which the data operand is stored is
given in the instruction.
The effective address is just a 16-bit number
written directly in the instruction.
Example:
MOV BX, [1354H]
MOV BL, [0400H]
The square brackets around the 1354H denotes
the contents of the memory location. When
executed, this instruction will copy the contents of
the memory location into BX register.
This addressing mode is called direct because the
displacement of the operand from the segment
base is specified directly in the instruction.
Group II : Addressing modes
for memory data

Addressing Modes
47
8086 Microprocessor
5. Based Addressing
In Register indirect addressing, name of the
register which holds the effective address (EA)
will be specified in the instruction.
Registers used to hold EA are any of the following
registers:
BX, BP, DI and SI.
Content of the DS register is used for base
address calculation.
Example:
MOV CX, [BX]
Operations:
EA = (BX)
BA = (DS) x 1610
MA = BA + EA
(CX)  (MA) or,
(CL)  (MA)
(CH)  (MA +1)
for memory data
Note : Register/ memory
enclosed in brackets refer
to content of register/
memory

Addressing Modes
48
8086 Microprocessor
5. Based Addressing
In Based Addressing, BX or BP is used to hold the
base value for effective address and a signed 8-bit
or unsigned 16-bit displacement will be specified
in the instruction.
In case of 8-bit displacement, it is sign extended
to 16-bit before adding to the base value.
When BX holds the base value of EA, 20-bit
physical address is calculated from BX and DS.
When BP holds the base value of EA, BP and SS is
used.
Example:
MOV AX, [BX + 08H]
Operations:
0008H  08H (Sign extended)
EA = (BX) + 0008H
BA = (DS) x 1610
MA = BA + EA
(AX)  (MA) or,
(AL)  (MA)
(AH)  (MA + 1)
for memory data

Addressing Modes
49
8086 Microprocessor
5. Based Addressing
SI or DI register is used to hold an index value for
memory data and a signed 8-bit or unsigned 16-
bit displacement will be specified in the
instruction.
Displacement is added to the index value in SI or
DI register to obtain the EA.
In case of 8-bit displacement, it is sign extended
to 16-bit before adding to the base value.
Example:
MOV CX, [SI + 0A2H]
Operations:
FFA2H  A2H (Sign extended)
EA = (SI) + FFA2H
BA = (DS) x 1610
MA = BA + EA
(CX)  (MA) or,
(CL)  (MA)
(CH)  (MA + 1)
for memory data

Addressing Modes
50
8086 Microprocessor
5. Based Addressing
In Based Index Addressing, the effective address
is computed from the sum of a base register (BX
or BP), an index register (SI or DI) and a
displacement.
Example:
MOV DX, [BX + SI + 0AH]
Operations:
000AH  0AH (Sign extended)
EA = (BX) + (SI) + 000AH
BA = (DS) x 1610
MA = BA + EA
(DX)  (MA) or,
(DL)  (MA)
(DH)  (MA + 1)
for memory data

Addressing Modes
51
8086 Microprocessor
5. Based Addressing
Employed in string operations to operate on string
data.
The effective address (EA) of source data is stored
in SI register and the EA of destination is stored in
DI register.
Segment register for calculating base address of
source data is DS and that of the destination data
is ES
Example: MOVS BYTE
Operations:
Calculation of source memory location:
EA = (SI) BA = (DS) x 1610 MA = BA + EA
Calculation of destination memory location:
EAE = (DI) BAE = (ES) x 1610 MAE = BAE + EAE
(MAE)  (MA)
If DF = 1, then (SI)  (SI) – 1 and (DI) = (DI) - 1
If DF = 0, then (SI)  (SI) +1 and (DI) = (DI) + 1
for memory data
Note : Effective address of
the Extra segment register

Addressing Modes
8086 Microprocessor
5. Based Addressing
These addressing modes are used to access data
from standard I/O mapped devices or ports.
In direct port addressing mode, an 8-bit port
address is directly specified in the instruction.
Example: IN AL, [09H]
Operations: PORTaddr = 09H
(AL)  (PORT)
Content of port with address 09H is
moved to AL register
In indirect port addressing mode, the instruction
will specify the name of the register which holds
the port address. In 8086, the 16-bit port address
is stored in the DX register.
Example: OUT [DX], AX
Operations: PORTaddr = (DX)
(PORT)  (AX)
Content of AX is moved to port
whose address is specified by DX
register. 52
Group III : Addressing
modes for I/O ports

Addressing Modes
53
8086 Microprocessor
5. Based Addressing
In this addressing mode, the effective address of
a program instruction is specified relative to
Instruction Pointer (IP) by an 8-bit signed
displacement.
Example: JZ 0AH
Operations:
000AH  0AH (sign extend)
If ZF = 1, then
EA = (IP) + 000AH
BA = (CS) x 1610
MA = BA + EA
If ZF = 1, then the program control jumps to
new address calculated above.
If ZF = 0, then next instruction of the
program is executed.
Group IV : Relative
Addressing mode

Addressing Modes
54
8086 Microprocessor
5. Based Addressing
Instructions using this mode have no operands.
The instruction itself will specify the data to be
operated by the instruction.
Example: CLC
This clears the carry flag to zero.
Group IV : Implied
Addressing mode

1. Data Transfer Instructions
2. Arithmetic Instructions
3. Logical Instructions
4. String manipulation Instructions
5. Process Control Instructions
6. Control Transfer Instructions
Instruction Set
56
8086 Microprocessor
8086 supports 6 types of instructions.

Instruction Set
57
8086 Microprocessor
Instructions that are used to transfer data/ address in to
registers, memory locations and I/O ports.
Generally involve two operands: Source operand and
Destination operand of the same size.
Source: Register or a memory location or an immediate data
Destination : Register or a memory location.
The size should be a either a byte or a word.
A 8-bit data can only be moved to 8-bit register/ memory
and a 16-bit data can be moved to 16-bit register/ memory.

Instruction Set
58
8086 Microprocessor
Mnemonics: MOV, XCHG, PUSH, POP, IN, OUT …
MOV reg2/ mem, reg1/ mem
MOV reg2, reg1
MOV mem, reg1
MOV reg2, mem
(reg2)  (reg1)
(mem)  (reg1)
(reg2)  (mem)
MOV reg/ mem, data
MOV reg, data
MOV mem, data
(reg)  data
(mem)  data
XCHG reg2/ mem, reg1
XCHG reg2, reg1
XCHG mem, reg1
(reg2)  (reg1)
(mem)  (reg1)

Instruction Set
59
8086 Microprocessor
PUSH reg16/ mem
PUSH reg16
PUSH mem
(SP)  (SP) – 2
MA S = (SS) x 1610 + SP
(MA S ; MA S + 1)  (reg16)
(SP)  (SP) – 2
MA S = (SS) x 1610 + SP
(MA S ; MA S + 1)  (mem)
POP reg16/ mem
POP reg16
POP mem
MA S = (SS) x 1610 + SP
(reg16)  (MA S ; MA S + 1)
(SP)  (SP) + 2
MA S = (SS) x 1610 + SP
(mem)  (MA S ; MA S + 1)
(SP)  (SP) + 2

Instruction Set
60
8086 Microprocessor
IN A, [DX]
IN AL, [DX]
IN AX, [DX]
PORTaddr = (DX)
(AL)  (PORT)
PORTaddr = (DX)
(AX)  (PORT)
IN A, addr8
IN AL, addr8
IN AX, addr8
(AL)  (addr8)
(AX)  (addr8)
OUT [DX], A
OUT [DX], AL
OUT [DX], AX
PORTaddr = (DX)
(PORT)  (AL)
PORTaddr = (DX)
(PORT)  (AX)
OUT addr8, A
OUT addr8, AL
OUT addr8, AX
(addr8)  (AL)
(addr8)  (AX)

Instruction Set
61
8086 Microprocessor
Mnemonics: ADD, ADC, SUB, SBB, INC, DEC, MUL, DIV, CMP…
ADD reg2/ mem, reg1/mem
ADC reg2, reg1
ADC reg2, mem
ADC mem, reg1
(reg2)  (reg1) + (reg2)
(reg2)  (reg2) + (mem)
(mem)  (mem)+(reg1)
ADD reg/mem, data
ADD reg, data
ADD mem, data
(reg)  (reg)+ data
(mem)  (mem)+data
ADD A, data
ADD AL, data8
ADD AX, data16
(AL)  (AL) + data8
(AX)  (AX) +data16

Instruction Set
62
8086 Microprocessor
ADC reg2/ mem, reg1/mem
ADC reg2, reg1
ADC reg2, mem
ADC mem, reg1
(reg2)  (reg1) + (reg2)+CF
(reg2)  (reg2) + (mem)+CF
(mem)  (mem)+(reg1)+CF
ADC reg/mem, data
ADC reg, data
ADC mem, data
(reg)  (reg)+ data+CF
(mem)  (mem)+data+CF
ADDC A, data
ADD AL, data8
ADD AX, data16
(AL)  (AL) + data8+CF
(AX)  (AX) +data16+CF

Instruction Set
63
8086 Microprocessor
SUB reg2/ mem, reg1/mem
SUB reg2, reg1
SUB reg2, mem
SUB mem, reg1
(reg2)  (reg1) - (reg2)
(reg2)  (reg2) - (mem)
(mem)  (mem) - (reg1)
SUB reg/mem, data
SUB reg, data
SUB mem, data
(reg)  (reg) - data
(mem)  (mem) - data
SUB A, data
SUB AL, data8
SUB AX, data16
(AL)  (AL) - data8
(AX)  (AX) - data16

Instruction Set
64
8086 Microprocessor
SBB reg2/ mem, reg1/mem
SBB reg2, reg1
SBB reg2, mem
SBB mem, reg1
(reg2)  (reg1) - (reg2) - CF
(reg2)  (reg2) - (mem)- CF
(mem)  (mem) - (reg1) –CF
SBB reg/mem, data
SBB reg, data
SBB mem, data
(reg)  (reg) – data - CF
(mem)  (mem) - data - CF
SBB A, data
SBB AL, data8
SBB AX, data16
(AL)  (AL) - data8 - CF
(AX)  (AX) - data16 - CF

Instruction Set
65
8086 Microprocessor
INC reg/ mem
INC reg8
INC reg16
INC mem
(reg8)  (reg8) + 1
(reg16)  (reg16) + 1
(mem)  (mem) + 1
DEC reg/ mem
DEC reg8
DEC reg16
DEC mem
(reg8)  (reg8) - 1
(reg16)  (reg16) - 1
(mem)  (mem) - 1

Instruction Set
66
8086 Microprocessor
MUL reg/ mem
MUL reg
MUL mem
For byte : (AX)  (AL) x (reg8)
For word : (DX)(AX)  (AX) x (reg16)
For byte : (AX)  (AL) x (mem8)
For word : (DX)(AX)  (AX) x (mem16)
IMUL reg/ mem
IMUL reg
IMUL mem
For byte : (AX)  (AL) x (reg8)
For word : (DX)(AX)  (AX) x (reg16)
For byte : (AX)  (AX) x (mem8)
For word : (DX)(AX)  (AX) x (mem16)

Instruction Set
67
8086 Microprocessor
DIV reg/ mem
DIV reg
DIV mem
For 16-bit :- 8-bit :
(AL)  (AX) :- (reg8) Quotient
(AH)  (AX) MOD(reg8) Remainder
(AX)  (DX)(AX) :- (reg16) Quotient
(DX)  (DX)(AX) MOD(reg16) Remainder
(AL)  (AX) :- (mem8) Quotient
(AH)  (AX) MOD(mem8) Remainder
(AX)  (DX)(AX) :- (mem16) Quotient
(DX)  (DX)(AX) MOD(mem16) Remainder

Instruction Set
68
8086 Microprocessor
IDIV reg/ mem
IDIV reg
IDIV mem
(AL)  (AX) :- (reg8) Quotient
(AH)  (AX) MOD(reg8) Remainder
(AX)  (DX)(AX) :- (reg16) Quotient
(DX)  (DX)(AX) MOD(reg16) Remainder
(AL)  (AX) :- (mem8) Quotient
(AH)  (AX) MOD(mem8) Remainder
(AX)  (DX)(AX) :- (mem16) Quotient
(DX)  (DX)(AX) MOD(mem16) Remainder

Instruction Set
69
8086 Microprocessor
CMP reg2/mem, reg1/ mem
CMP reg2, reg1
CMP reg2, mem
CMP mem, reg1
Modify flags  (reg2) – (reg1)
If (reg2) > (reg1) then CF=0, ZF=0, SF=0
If (reg2) < (reg1) then CF=1, ZF=0, SF=1
If (reg2) = (reg1) then CF=0, ZF=1, SF=0
Modify flags  (reg2) – (mem)
If (reg2) > (mem) then CF=0, ZF=0, SF=0
If (reg2) < (mem) then CF=1, ZF=0, SF=1
If (reg2) = (mem) then CF=0, ZF=1, SF=0
Modify flags  (mem) – (reg1)
If (mem) > (reg1) then CF=0, ZF=0, SF=0
If (mem) < (reg1) then CF=1, ZF=0, SF=1
If (mem) = (reg1) then CF=0, ZF=1, SF=0

Instruction Set
70
8086 Microprocessor
CMP reg/mem, data
CMP reg, data
CMP mem, data
Modify flags  (reg) – (data)
If (reg) > data then CF=0, ZF=0, SF=0
If (reg) < data then CF=1, ZF=0, SF=1
If (reg) = data then CF=0, ZF=1, SF=0
Modify flags  (mem) – (mem)
If (mem) > data then CF=0, ZF=0, SF=0
If (mem) < data then CF=1, ZF=0, SF=1
If (mem) = data then CF=0, ZF=1, SF=0

Instruction Set
71
8086 Microprocessor
CMP A, data
CMP AL, data8
CMP AX, data16
Modify flags  (AL) – data8
If (AL) > data8 then CF=0, ZF=0, SF=0
If (AL) < data8 then CF=1, ZF=0, SF=1
If (AL) = data8 then CF=0, ZF=1, SF=0
Modify flags  (AX) – data16
If (AX) > data16 then CF=0, ZF=0, SF=0
If (mem) < data16 then CF=1, ZF=0, SF=1
If (mem) = data16 then CF=0, ZF=1, SF=0

Instruction Set
72
8086 Microprocessor
Mnemonics: AND, OR, XOR, TEST, SHR, SHL, RCR, RCL …

Instruction Set
73
8086 Microprocessor

Instruction Set
74
8086 Microprocessor

Instruction Set
75
8086 Microprocessor

Instruction Set
76
8086 Microprocessor

Instruction Set
77
8086 Microprocessor

Instruction Set
78
8086 Microprocessor

Instruction Set
79
8086 Microprocessor

4. String Manipulation Instructions
Instruction Set
80
8086 Microprocessor
 String : Sequence of bytes or words
 8086 instruction set includes instruction for string movement, comparison,
scan, load and store.
 REP instruction prefix : used to repeat execution of string instructions
 String instructions end with S or SB or SW.
S represents string, SB string byte and SW string word.
 Offset or effective address of the source operand is stored in SI register and
that of the destination operand is stored in DI register.
 Depending on the status of DF, SI and DI registers are automatically
updated.
 DF = 0  SI and DI are incremented by 1 for byte and 2 for word.
 DF = 1  SI and DI are decremented by 1 for byte and 2 for word.

Instruction Set
81
8086 Microprocessor
Mnemonics: REP, MOVS, CMPS, SCAS, LODS, STOS
REP
REPZ/ REPE
(Repeat CMPS or SCAS until
ZF = 0)
REPNZ/ REPNE
(Repeat CMPS or SCAS until
ZF = 1)
While CX  0 and ZF = 1, repeat execution of
string instruction and
(CX)  (CX) – 1
While CX  0 and ZF = 0, repeat execution of
string instruction and
(CX)  (CX) - 1

Instruction Set
82
8086 Microprocessor
MOVS
MOVSB
MOVSW
MA = (DS) x 1610 + (SI)
MAE = (ES) x 1610 + (DI)
(MAE)  (MA)
If DF = 0, then (DI)  (DI) + 1; (SI)  (SI) + 1
If DF = 1, then (DI)  (DI) - 1; (SI)  (SI) - 1
MA = (DS) x 1610 + (SI)
MAE = (ES) x 1610 + (DI)
(MAE ; MAE + 1)  (MA; MA + 1)

Instruction Set
83
8086 Microprocessor
CMPS
CMPSB
CMPSW
MA = (DS) x 1610 + (SI)
MAE = (ES) x 1610 + (DI)
Modify flags  (MA) - (MAE)
If (MA) > (MAE), then CF = 0; ZF = 0; SF = 0
If (MA) < (MAE), then CF = 1; ZF = 0; SF = 1
If (MA) = (MAE), then CF = 0; ZF = 1; SF = 0
For byte operation
For word operation
Compare two string byte or string word

Instruction Set
84
8086 Microprocessor
SCAS
SCASB
SCASW
MAE = (ES) x 1610 + (DI)
Modify flags  (AL) - (MAE)
If (AL) > (MAE), then CF = 0; ZF = 0; SF = 0
If (AL) < (MAE), then CF = 1; ZF = 0; SF = 1
If (AL) = (MAE), then CF = 0; ZF = 1; SF = 0
If DF = 0, then (DI)  (DI) + 1
If DF = 1, then (DI)  (DI) – 1
MAE = (ES) x 1610 + (DI)
Modify flags  (AL) - (MAE)
If (AX) > (MAE ; MAE + 1), then CF = 0; ZF = 0; SF = 0
If (AX) < (MAE ; MAE + 1), then CF = 1; ZF = 0; SF = 1
If (AX) = (MAE ; MAE + 1), then CF = 0; ZF = 1; SF = 0
If DF = 0, then (DI)  (DI) + 2
If DF = 1, then (DI)  (DI) – 2
Scan (compare) a string byte or word with accumulator

Instruction Set
85
8086 Microprocessor
LODS
LODSB
LODSW
MA = (DS) x 1610 + (SI)
(AL)  (MA)
If DF = 0, then (SI)  (SI) + 1
If DF = 1, then (SI)  (SI) – 1
MA = (DS) x 1610 + (SI)
(AX)  (MA ; MA + 1)
If DF = 0, then (SI)  (SI) + 2
If DF = 1, then (SI)  (SI) – 2
Load string byte in to AL or string word in to AX

Instruction Set
86
8086 Microprocessor
STOS
STOSB
STOSW
MAE = (ES) x 1610 + (DI)
(MAE)  (AL)
If DF = 0, then (DI)  (DI) + 1
If DF = 1, then (DI)  (DI) – 1
MAE = (ES) x 1610 + (DI)
(MAE ; MAE + 1 )  (AX)
If DF = 0, then (DI)  (DI) + 2
If DF = 1, then (DI)  (DI) – 2
Store byte from AL or word from AX in to string

Mnemonics Explanation
STC Set CF  1
CLC Clear CF  0
CMC Complement carry CF  CF/
STD Set direction flag DF  1
CLD Clear direction flag DF  0
STI Set interrupt enable flag IF  1
CLI Clear interrupt enable flag IF  0
NOP No operation
HLT Halt after interrupt is set
WAIT Wait for TEST pin active
ESC opcode mem/ reg Used to pass instruction to a coprocessor
which shares the address and data bus
with the 8086
LOCK Lock bus during next instruction
5. Processor Control Instructions
Instruction Set
87
8086 Microprocessor

Instruction Set
88
8086 Microprocessor
Transfer the control to a specific destination or target instruction
Do not affect flags
CALL reg/ mem/ disp16 Call subroutine
RET Return from subroutine
JMP reg/ mem/ disp8/ disp16 Unconditional jump
 8086 Unconditional transfers

Instruction Set
89
8086 Microprocessor
 8086 signed conditional
branch instructions
 8086 unsigned conditional
branch instructions
Checks flags
If conditions are true, the program control is
transferred to the new memory location in the same
segment by modifying the content of IP

Instruction Set
90
8086 Microprocessor
Name Alternate name
JE disp8
Jump if equal
JZ disp8
Jump if result is 0
JNE disp8
Jump if not equal
JNZ disp8
Jump if not zero
JG disp8
Jump if greater
JNLE disp8
Jump if not less or
equal
JGE disp8
Jump if greater
than or equal
JNL disp8
Jump if not less
JL disp8
Jump if less than
JNGE disp8
Jump if not
greater than or
equal
JLE disp8
Jump if less than
or equal
JNG disp8
Jump if not
greater
 8086 signed conditional
branch instructions
 8086 unsigned conditional
branch instructions
Name Alternate name
JE disp8
Jump if equal
JZ disp8
Jump if result is 0
JNE disp8
Jump if not equal
JNZ disp8
Jump if not zero
JA disp8
Jump if above
JNBE disp8
Jump if not below
or equal
JAE disp8
Jump if above or
equal
JNB disp8
Jump if not below
JB disp8
Jump if below
JNAE disp8
Jump if not above
or equal
JBE disp8
Jump if below or
equal
JNA disp8
Jump if not above

Instruction Set
91
8086 Microprocessor
JC disp8 Jump if CF = 1
JNC disp8 Jump if CF = 0
JP disp8 Jump if PF = 1
JNP disp8 Jump if PF = 0
JO disp8 Jump if OF = 1
JNO disp8 Jump if OF = 0
JS disp8 Jump if SF = 1
JNS disp8 Jump if SF = 0
JZ disp8 Jump if result is zero, i.e, Z = 1
JNZ disp8 Jump if result is not zero, i.e, Z = 1
 8086 conditional branch instructions affecting individual flags

Assemble Directives
93
8086 Microprocessor
Instructions to the Assembler regarding the program being
executed.
Control the generation of machine codes and organization of
the program; but no machine codes are generated for
assembler directives.
Also called ‘pseudo instructions’
Used to :
› specify the start and end of a program
› attach value to variables
› allocate storage locations to input/ output data
› define start and end of segments, procedures, macros etc..

Assemble Directives
94
8086 Microprocessor
Define Byte
Define a byte type (8-bit) variable
Reserves specific amount of memory
locations to each variable
Range : 00H – FFH for unsigned value;
00H – 7FH for positive value and
80H – FFH for negative value
General form : variable DB value/ values
Example:
LIST DB 7FH, 42H, 35H
Three consecutive memory locations are reserved for
the variable LIST and each data specified in the
instruction are stored as initial value in the reserved
memory location
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
FAR
NEAR
ENDP
SHORT
MACRO
ENDM

Assemble Directives
95
8086 Microprocessor
Define Word
Define a word type (16-bit) variable
Reserves two consecutive memory locations
to each variable
Range : 0000H – FFFFH for unsigned value;
0000H – 7FFFH for positive value and
8000H – FFFFH for negative value
General form : variable DW value/ values
Example:
ALIST DW 6512H, 0F251H, 0CDE2H
Six consecutive memory locations are reserved for
the variable ALIST and each 16-bit data specified in
the instruction is stored in two consecutive memory
location.
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
FAR
NEAR
ENDP
SHORT
MACRO
ENDM

Assemble Directives
96
8086 Microprocessor
SEGMENT : Used to indicate the beginning of
a code/ data/ stack segment
ENDS : Used to indicate the end of a code/
data/ stack segment
General form:
Segnam SEGMENT
…
…
…
…
…
…
Segnam ENDS
Program code
or
Data Defining Statements
User defined name of
the segment
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
FAR
NEAR
ENDP
SHORT
MACRO
ENDM

Assemble Directives
97
8086 Microprocessor
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
FAR
NEAR
ENDP
SHORT
MACRO
ENDM
Informs the assembler the name of the
program/ data segment that should be used
for a specific segment.
General form:
Segment Register
ASSUME segreg : segnam, .. , segreg : segnam
the segment
ASSUME CS: ACODE, DS:ADATA Tells the compiler that the
instructions of the program are
stored in the segment ACODE and
data are stored in the segment
ADATA
Example:

Assemble Directives
98
8086 Microprocessor
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
FAR
NEAR
ENDP
SHORT
MACRO
ENDM
ORG (Origin) is used to assign the starting address
(Effective address) for a program/ data segment
END is used to terminate a program; statements
after END will be ignored
EVEN : Informs the assembler to store program/
data segment starting from an even address
EQU (Equate) is used to attach a value to a variable
ORG 1000H Informs the assembler that the statements
following ORG 1000H should be stored in
memory starting with effective address
1000H
LOOP EQU 10FEH Value of variable LOOP is 10FEH
_SDATA SEGMENT
ORG 1200H
A DB 4CH
EVEN
B DW 1052H
_SDATA ENDS
In this data segment, effective address of
memory location assigned to A will be 1200H
and that of B will be 1202H and 1203H.
Examples:

Assemble Directives
99
8086 Microprocessor
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
ENDP
FAR
NEAR
SHORT
MACRO
ENDM
PROC Indicates the beginning of a procedure
ENDP End of procedure
FAR Intersegment call
NEAR Intrasegment call
General form
procname PROC[NEAR/ FAR]
…
…
…
RET
procname ENDP
Program statements of the
procedure
Last statement of the
procedure
the procedure

Assemble Directives
100
8086 Microprocessor
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
ENDP
FAR
NEAR
SHORT
MACRO
ENDM
ADD64 PROC NEAR
…
…
…
RET
ADD64 ENDP
The subroutine/ procedure named ADD64 is
declared as NEAR and so the assembler will
code the CALL and RET instructions involved
in this procedure as near call and return
CONVERT PROC FAR
…
…
…
RET
CONVERT ENDP
The subroutine/ procedure named CONVERT
is declared as FAR and so the assembler will
code the CALL and RET instructions involved
in this procedure as far call and return
Examples:

Assemble Directives
101
8086 Microprocessor
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
ENDP
FAR
NEAR
SHORT
MACRO
ENDM
Reserves one memory location for 8-bit
signed displacement in jump instructions
JMP SHORT
AHEAD
The directive will reserve one
memory location for 8-bit
displacement named AHEAD
Example:

Assemble Directives
102
8086 Microprocessor
DB
DW
SEGMENT
ENDS
ASSUME
ORG
END
EVEN
EQU
PROC
ENDP
FAR
NEAR
SHORT
MACRO
ENDM
MACRO Indicate the beginning of a macro
ENDM End of a macro
General form:
macroname MACRO[Arg1, Arg2 ...]
…
…
…
macroname ENDM
Program
statements in
the macro
the macro

Interfacing memory and i/o ports

Memory
105
8086 Microprocessor
Memory
Processor Memory
Primary or Main Memory
Secondary Memory
Store
Programs
and Data
 Registers inside a microcomputer
 Store data and results temporarily
 No speed disparity
 Cost 
 Storage area which can be directly
accessed by microprocessor
 Store programs and data prior to
execution
 Should not have speed disparity with
processor  Semi Conductor
memories using CMOS technology
 ROM, EPROM, Static RAM, DRAM
 Storage media comprising of slow
devices such as magnetic tapes and
disks
 Hold large data files and programs:
Operating system, compilers,
databases, permanent programs etc.

Memory organization in 8086
106
8086 Microprocessor
Memory IC’s : Byte oriented
8086 : 16-bit
Word : Stored by two
consecutive memory locations;
for LSB and MSB
Address of word : Address of
LSB
Bank 0 : A0 = 0  Even
addressed memory bank
Bank 1 : 𝑩𝑯𝑬 = 0  Odd
addressed memory bank

107
8086 Microprocessor
Operation 𝑩𝑯𝑬 A0 Data Lines Used
1 Read/ Write byte at an even address 1 0 D7 – D0
2 Read/ Write byte at an odd address 0 1 D15 – D8
3 Read/ Write word at an even address 0 0 D15 – D0
4 Read/ Write word at an odd address 0 1 D15 – D0 in first operation
byte from odd bank is
transferred
1 0 D7 – D0 in first operation
byte from odd bank is
transferred

108
8086 Microprocessor
Available memory space = EPROM + RAM
Allot equal address space in odd and even
bank for both EPROM and RAM
Can be implemented in two IC’s (one for
even and other for odd) or in multiple IC’s

Interfacing SRAM and EPROM
109
8086 Microprocessor
Memory interface  Read from and write in
to a set of semiconductor memory IC chip
EPROM  Read operations
RAM  Read and Write
In order to perform read/ write operations,
Memory access time  read / write time of
the processor
Chip Select (CS) signal has to be generated
Control signals for read / write operations
Allot address for each memory location

110
8086 Microprocessor
Typical Semiconductor IC Chip
No of
Address
pins
Memory capacity Range of
address in
hexa
In Decimal In kilo In hexa
20 220= 10,48,576 1024 k = 1M 100000 00000
to
FFFFF

111
8086 Microprocessor
Memory map of 8086
RAM are mapped at the beginning; 00000H is allotted to RAM
EPROM’s are mapped at FFFFFH
 Facilitate automatic execution of monitor programs
and creation of interrupt vector table

112
8086 Microprocessor
Monitor Programs
 Programing 8279 for keyboard scanning and display
refreshing
 Programming peripheral IC’s 8259, 8257, 8255,
8251, 8254 etc
 Initialization of stack
 Display a message on display (output)
 Initializing interrupt vector table
8279 Programmable keyboard/ display controller
8257 DMA controller
8259 Programmable interrupt controller
8255 Programmable peripheral interface
Note :

Interfacing I/O and peripheral devices
113
8086 Microprocessor
I/O devices
 For communication between microprocessor and
outside world
 Keyboards, CRT displays, Printers, Compact Discs
etc.

 Data transfer types
Microprocessor I/ O devices
Ports / Buffer IC’s
(interface circuitry)
Programmed I/ O
Data transfer is accomplished
through an I/O port
controlled by software
Interrupt driven I/ O
I/O device interrupts the
processor and initiate data
transfer
Direct memory access
Data transfer is achieved by
bypassing the microprocessor
Memory mapped
I/O mapped

8086 and 8088 comparison
114
8086 Microprocessor
Memory mapping I/O mapping
20 bit address are provided for I/O
devices
8-bit or 16-bit addresses are
provided for I/O devices
The I/O ports or peripherals can be
treated like memory locations and
so all instructions related to
memory can be used for data
transmission between I/O device
and processor
Only IN and OUT instructions can be
used for data transfer between I/O
device and processor
Data can be moved from any
register to ports and vice versa
Data transfer takes place only
between accumulator and ports
When memory mapping is used for
I/O devices, full memory address
space cannot be used for
addressing memory.
 Useful only for small systems
where memory requirement is less
Full memory space can be used for
addressing memory.
 Suitable for systems which
require large memory capacity
For accessing the memory mapped
devices, the processor executes
memory read or write cycle.
 M / 𝐈𝐎 is asserted high
For accessing the I/O mapped
devices, the processor executes I/O
read or write cycle.
 M / 𝐈𝐎 is asserted low

PREPARED BY
DEPT & SEM : EEE & III/II SEM
SUBJECT NAME: DIGITAL COMPUTE PLATFORMS
COURSE CODE : 19A02601T
UNIT : II
: Mrs C. MUNIKANTHA

OVER VIEW
ASSEMBLY LANGUAGE PROGRAMMING & I/O INTERFACE
Assembler directives
macros –
simple programs involving logical
branch instructions
sorting
evaluating arithmetic expressions
string manipulations
8255 PPI
various modes of operation
A/D - D/A converter interfacing
Memory interfacing to 8086
interrupt structure of 8086
vector interrupt table
interrupt service routine
interfacing interrupt controller 8259
Need of DMA
serial communication standards
serial data transfer schemes

ASSEMBLER DIRECTIVE:
Assembler directives are non executable instructions which are pseudo
instructions which helps assembler to execute a program.
Few Examples for assembler directives are as follows
Org 2000h
Start:
End start
Assume DS: Data

The SEGMENT directive is used to indicate the start of a logical segment.
Preceding the SEGMENT directive is the name you want to give the segment.
For example, the statement CODE SEGMENT indicates to the assembler the
start of a logical segment called CODE. The SEGMENT and ENDS directive are
used to “bracket” a logical segment containing code of data.

Additional terms are often added to a SEGMENT directive statement to indicate
some special way in which we want the assembler to treat the segment. The
statement CODE SEGMENT WORD tells the assembler that we want the content of
this segment located on the next available word (even address) when segments
are combined and given absolute addresses.
Without this WORD addition, the segment will be located on the next available
paragraph (16-byte) address, which might waste as much as 15 bytes of memory.
The statement CODE SEGMENT PUBLIC tells the assembler that the segment may
be put together with other segments named CODE from other assembly modules
when the modules are linked together.

CODE SEGMENT
Start of logical segment containing code
instruction statements
CODE ENDS End of segment named CODE
ENDS (End Segment)
This directive is used with the name of a segment to indicate the end of that
logical segment.
END (End Procedure)
The END directive is put after the last statement of a program to tell the assembler
that this is the end of the program module. The assembler will ignore any
statements after an END directive, so you should make sure to use only one END
directive at the very end of your program module. A carriage return is required after
the END directive

ASSUME
The ASSUME directive is used tell the assembler the name of the logical
segment it should use for a specified segment. The statement ASSUME CS: CODE,
for example, tells the assembler that the instructions for a program are in a
logical segment named CODE.
The statement ASSUME DS: DATA tells the assembler that for any program
instruction, which refers to the data segment, it should use the logical segment
called DATA.
DB (Define Byte)
The DB directive is used to declare a byte type variable, or a set aside one or
more storage locations of type byte in memory

PRICES DB 49H, 98H, 29H Declare array of 3 bytes named PRICE and initialize
them with specified values.
NAMES DB “THOMAS” Declare array of 6 bytes and initialize with ASCII
codes for the letters in THOMAS.
RESULT DB 100 DUP (?) Set aside 100 bytes of storage in memory and give
it the name RESULT. But leave the 100 bytes un-initialized.
PRESSURE DB 20H DUP (0) Set aside 20H bytes of storage in memory, give it
the name PRESSURE and put 0 in all 20H locations.

DD (Define Double Word)
The DD directive is used to declare a variable of type double word or to reserve
memory locations, which can be accessed as type double word.
The statement ARRAY DD 25629261H, for example, will define a double word named
ARRAY and initialize the double word with the specified value when the program is loaded
into memory to be run. The low word, 9261H, will be put in memory at a lower address
than the high word.
DQ (Define Quadword)
The DQ directive is used to tell the assembler to declare a variable 4 words in length
or to reserve 4 words of storage in memory. The statement BIG_NUMBER DQ
243598740192A92BH, for example, will declare a variable named BIG_NUMBER and
initialize the 4 words set aside with the specified number when the program is loaded into
memory to be run.

DT (Define Ten Bytes)
The DT directive is used to tell the assembler to declare a variable, which
is 10 bytes in length or to reserve 10 bytes of storage in memory. The
statement PACKED_BCD DT 11223344556677889900 will declare an array
named PACKED_BCD, which is 10 bytes in length. It will initialize the 10 bytes
with the values 11, 22, 33, 44, 55, 66, 77, 88, 99, and 00 when the program is
loaded into memory to be run. The statement RESULT DT 20H DUP (0) will
declare an array of 20H blocks of 10 bytes each and initialize all 320 bytes to 00
when the program is loaded into memory to be run.

DW (Define Word)
The DW directive is used to tell the assembler to define a variable of type
word or to reserve storage locations of type word in memory. The statement
MULTIPLIER DW 437AH, for example, declares a variable of type word named
MULTIPLIER, and initialized with the value 437AH when the program is loaded into
memory to be run.
WORDS DW 1234H, 3456H Declare an array of 2 words and initialize them
with the specified values.
STORAGE DW 100 DUP (0) Reserve an array of 100 words of memory and
initialize all 100 words with 0000. Array is named as STORAGE.
STORAGE DW 100 DUP (?) Reserve 100 word of storage in memory and give it
the name STORAGE, but leave the words un-
initialized.

EQU (Equate)
EQU is used to give a name to some value or symbol. Each time the assembler finds the
given name in the program, it replaces the name with the value or symbol you equated
with that name. Suppose, for example, you write the statement
FACTOR EQU 03H at the start of your program, and later in the program you write the
instruction statement ADD AL, FACTOR. When the assembler codes this instruction
statement, it will code it as if you had written the instruction ADD AL, 03H.
CONTROL EQU 11000110 B MOV AL, CONTROL
DECIMAL_ADJUST EQU DAA ADD AL, BL DECIMAL_ADJUST
Replacement
Assignment
Create clearer mnemonic for DAA Add BCD numbers
Keep result in BCD format

OFFSET
OFFSET is an operator, which tells the assembler to determine the offset
or displacement of a named data item (variable), a procedure from the start of
the segment, which contains it. When the assembler reads the statement MOV
BX, OFFSET PRICES, for example, it will determine the offset of the variable
PRICES from the start of the segment in which PRICES is defined and will
load this value into BX.

PTR (POINTER)
The PTR operator is used to assign a specific type to a variable or a label. It is
necessary to do this in any instruction where the type of the operand is not clear. When the
assembler reads the instruction INC [BX], for example, it will not know whether to
increment the byte pointed to by BX. We use the PTR operator to clarify how we want the
assembler to code the instruction. The statement INC BYTE PTR [BX] tells the assembler
that we want to increment the byte pointed to by BX. The statement INC WORD PTR [BX]
tells the assembler that we want to increment the word pointed to by BX. The PTR operator
assigns the type specified before PTR to the variable specified after PTR.
We can also use the PTR operator to clarify our intentions when we use indirect Jump
instructions. The statement JMP [BX], for example, does not tell the assembler whether to
code the instruction for a near jump. If we want to do a near jump, we write the instruction
as JMP WORD PTR [BX]. If we want to do a far jump, we write the instruction as JMP
DWORD PTR [BX].

EVEN (Align On Even Memory Address)
As an assembler assembles a section of data declaration or instruction statements,
it uses a location counter to keep track of how many bytes it is from the start of a
segment at any time. The EVEN directive tells the assembler to increment the location
counter to the next even address, if it is not already at an even address. A NOP
instruction will be inserted in the location incremented over.
DATA SEGMENT
SALES DB 9 DUP (?) Location counter will point to 0009 after this instruction.
EVEN Increment location counter to 000AH
INVENTORY DW 100 DUP (0) Array of 100 words starting on even address for
quicker read DATA ENDS

Procedure
PROC (Procedure)
The PROC directive is used to identify the start of a procedure. The PROC
directive follows a name you give the procedure. After the PROC directive, the
term near or the term far is used to specify the type of the procedure. The
statement DIVIDE PROC FAR, for example, identifies the start of a procedure
named DIVIDE and tells the assembler that the procedure is far (in a segment
with different name from the one that contains the instructions which calls the
procedure). The PROC directive is used with the ENDP directive to “bracket”
ENDP (End Procedure)
The directive is used along with the name of the procedure to indicate the end
of a procedure to the assembler. The directive, together with the procedure
directive, PROC, is used to “bracket” a procedure

Procedure
SQUARE_ROOT PROC Start of procedure.
SQUARE_ROOT ENDP End of procedure.

Macros
A Macro is a set of instructions grouped under a single unit
The Macro is different from the Procedure in a way that unlike calling and
returning the control as in procedures, the processor generates the code in
the program every time whenever and wherever a call to the Macro is made.
A Macro can be defined in a program using the following assembler
directives: MACRO and ENDM.
All the instructions that belong to the Macro lie within these two assembler
directives. The following is the syntax for defining a Macro in the 8086
Microprocessor
Macro_name MACRO [ list of parameters ]
Instruction 1
Instruction 2
-- - - - - - - - - -
- - - - - - - - - - -
- - - - - - - - - - - - -
Instruction n
ENDM

Macros
A Macro is a set of instructions grouped under a single unit
The Macro is different from the Procedure in a way that unlike calling and
returning the control as in procedures, the processor generates the code in
the program every time whenever and wherever a call to the Macro is made.
A Macro can be defined in a program using the following assembler
directives: MACRO and ENDM.
. All the instructions that belong to the Macro lie within these two assembler
directives. The following is the syntax for defining a Macro in the 8086
Microprocessor
Macro_name MACRO [ list of parameters ]
Instruction 1
Instruction 2
-- - - - - -
-- - - - - - -
- - - - - - - -
Instruction n
ENDM

MOV SI, 5000
MOV CL, [SI]
MOV CH, 00
INC SI
MOV AL, [SI]
DEC CL
INC SI
SVEW : CMP AL,[SI]
JNC SVEC
Largest Number
MOV AL, [SI]
SVEC: INC SI
LOOP SVEW
MOV [6000], AL
HLT

ASCENDING ORDER
MOV SI, 5000H
MOV CL, [SI]
DEC CL
EEE: MOV SI, 5000H
MOV CH, [SI]
DEC CH
INC SI
VEMU: MOV AL, [SI]
INC SI
CMP AL, [SI]
JC SVEW
XCHG AL, [SI]
DEC SI
XCHG AL, [SI]
INC SI
SVEW: DEC CH
JNZ VEMU
DEC CL
JNZ EEE
HLT

MOV SI, 5000
MOV CL, [SI]
MOV CH, 00
INC SI
MOV AL, [SI]
DEC CL
INC SI
SVEW : CMP AL,[SI]
JC SVEC
Smallest Number
MOV AL, [SI]
SVEC: INC SI
LOOP SVEW
MOV [6000], AL
HLT

DESCENDING ORDER
MOV SI, 5000H
MOV CL, [SI]
DEC CL
EEE: MOV SI, 5000H
MOV CH, [SI]
DEC CH
INC SI
SVEC: MOV AL, [SI]
INC SI
CMP AL, [SI]
JNC SVEW
XCHG AL, [SI]
DEC SI
XCHG AL, [SI]
INC SI
SVEW: DEC CH
JNZ SVEC
DEC CL
JNZ EEE
HLT

Factorial
MOV CX, [5000]
MOV AX, 0001
MOV DX, 0000
SVEW: MUL CX
LOOP SVEW
MOV [6000], AX
MOV [6002], DX
HLT

Fibonacci sequence
MOV AL, 00H
MOV SI, 5000H
MOV [SI], AL
ADD SI, 01H
ADD AL, 01H
MOV [SI], AL
SUB CX, 0002H
L1: MOV AL, [SI-1]
ADD AL, [SI]
ADD SI, 01H
MOV [SI], AL
LOOP L1
HLT

STRING MANIPULATION – MOVE
MOV CL,05H
MOV SI,1100H
MOV DI,1200H
CLD
L1 MOVSB
LOOP L1
HLT

Register selection
S’ A1 A0 Selection Address
0 0 0 PORT A 80 H
0 0 1 PORT B 81 H
0 1 0 PORT C 82 H
0 1 1
Control
Register
83 H
1 X X No Seletion X

8255 FEATURES
 The port A lines are identified by symbols PA0-PA7 while the port C lines are
Identified as PC4-PC7.
 Similarly, Group B contains an 8-bit port B, containing lines PB0-PB7 and a 4-bit
port C with lower bits PC0- PC3.
 The port C upper and port C lower can be used in combination as an 8-bit port C.
 Both the port C is assigned the same address.
 Thus one may have either three 8-bit I/O ports or two 8-bit and two 4-bit ports
from 8255.
 All of these ports can function independently either as input or as output ports.
 This can be achieved by programming the bits of an internal register of 8255
called as control word register (CWR).

Modes of 8255
Modes of Operation of 8255
These are two basic modes of operation of 8255.
I/O mode and Bit Set-Reset mode (BSR).
In I/O mode, the 8255 ports work as programmable I/O ports, while in BSR mode only
port C (PC0-PC7) can be used to set or reset its individual port bits.
Under the I/O mode of operation, further there are three modes of operation of 8255,
so as to support different types of applications, mode 0, mode 1 and mode 2.
BSR Mode: In this mode any of the 8-bits of port C can be set or reset depending on D0
of the control word. The bit to be set or reset is selected by bit select flags D3, D2 and
D1 of the CWR as given in table.

microprocessor and microcontroller 8086 /8085

I/O Modes:
I/O Modes:
Mode 0 (Basic I/O mode): This mode is also called as basic input/output Mode. This mode
provides simple input and output capabilities using each of the three ports. Data can be
simply read from and written to the input and output ports respectively, after appropriate
initialization.

Mode 1
Mode 1: (Strobed input/output mode ) In this mode the handshaking control the
input and output action of the specified port. Port C lines PC0-PC2, provide strobe or
handshake lines for port B.
This group which includes port B and PC0-PC2 is called as group B for Strobed data
input/output. Port C lines PC3-PC5 provides strobe lines for port A.
This group including port A and PC3-PC5 from group A. Thus port C is utilized for
generating handshake signals.
The salient features of mode 1 are listed as follows
• Two groups – group A and group B are available for strobed data transfer.
• Each group contains one 8-bit data I/O port and one 4-bit control/data port.
• The 8-bit data port can be either used as input and output port. The inputs and
outputs both are latched.
Out of 8-bit port C, PC0-PC2 are used to generate control signals for port B
andPC3-PC5 are used to generate control signals for port A. the lines PC6, PC7 may be
used as independent data lines.

Mode 2 (Strobed bidirectional I/O): This mode of operation of 8255 is also called as
strobed bidirectional I/O.
•This mode of operation provides 8255 with additional features for communicating with
a peripheral device on an 8-bit data bus.
•Handshaking signals are provided to maintain proper data flow and synchronization
between the data transmitter and receiver.
•The interrupt generation and other functions are similar to mode 1.
•In this mode, 8255 is a bidirectional 8-bit port with handshake signals. The Rd and WR
signals decide whether the 8255 is going to operate as an input port or output port.
•The Salient features of Mode 2 of 8255 are listed as follows:
The single 8-bit port in group A is available.
The 8-bit port is bidirectional and additionally a 5-bit control port is available.
Three I/O lines are available at port C.( PC2 – PC0 )
Inputs and outputs are both latched.

Interfacing ADC Port A
Interfacing ADC Port A acts as a 8-bit input data port to
receive the digital data output from the ADC.
The 8255 control word is written as follows:
D7 D6 D5 D4 D3 D2 D1 D0
1 0 0 1 1 0 0 0

Interfacing ADC using ALP
Interfacing ADC The required ALP is as follows:
MOV AL, 98h ; initializes 8255.
OUT CWR, AL ;
MOV AL, 02h ;Select I/P2 as analog input
OUT Port B, AL ;
MOV AL, 00h ;Give start of conversion
OUT Port C, AL ; pulse to the ADC
MOV AL, 01h
OUT Port C, AL
MOV AL, 00h
OUT Port C, AL

A/D and D/A converter
SAWTOOTH WAVEFORM
LABEL MNEMONICS
MOV AL,80H
OUT 76,AL
START: MOV AL,0H
OUT 70H,AL
OUT 72,AL
INC AL
JMP START

DAC
LABEL MNEMONICS
MOV AL,80
OUT 76,AL
START MOV AL,00
REPEAT OUT 70,A
OUT 72,AL
INC AL
CMP AL.FF
JNZ REPEAT
MOV AL.FF
AGAIN OUT 70,AL
OUT 72,AL
DEC AL
CMP AL,00
JNZ AGAIN
JMP START

Memory interfacing to 8086
Memory interface
Memory is divided into two banks ODD and EVEN.
The data bus is 16-bits wide.
The IO/ M pin is replaced with M/ IO (8086).
BHE , Bus High Enable, control signal is added.
Address pin A 0 (or BLE , Bus Low Enable ) is used differently.
The 16-bit data bus presents a new problem:
The microprocessor must be able to read and write data to any 16-bit location in
addition to any 8-bit location.
The data bus and memory are divided into banks:

Memory interface
BHE and BLE are used to select one or both:
BHE BLE(A0) Function
0 0 Both banks enabled for 16-bit transfer
0 1 High bank enabled for an 8-bit transfer
1 0 Low bank enabled for an 8-bit transfer
1 1 No banks selected Bank selection can be accomplished in two ways:
Separate write decoders for each bank (which drive CS ).
A separate write signal (strobe) to each bank (which drive WE ).
Note that 8-bit read requests in this scheme are handled by the microprocessor (it
selects the bits it wants to read from the 16-bits on the bus).

Memory interfacing
Fig . Schematic diagram of a memory

Memory interfacing
Fig. Memory map
Fig. Memory chip selection

Interrupt structure of 8086
8086 Interrupt response

Interrupt is the method of creating a temporary halt during program execution and
allows peripheral devices to access the microprocessor. The microprocessor responds to
that interrupt with an ISR (Interrupt Service Routine), which is a short program to
instruct the microprocessor on how to handle the interrupt.
The are two types of interrupts in a 8086 microprocessor.
They are hardware interrupts and software interrupts.
NMI
It is a single non-maskable interrupt pin (NMI) having higher priority than the maskable
interrupt request pin (INTR)and it is of type 2 interrupt.
When this interrupt is activated, these following actions take place
•Completes the current instruction that is in progress.
•Pushes the Flag register values on to the stack.
•Pushes the CS (code segment) value and IP (instruction pointer) value of the return
address on to the stack.
•IP is loaded from the contents of the word location 00008H.
•CS is loaded from the contents of the next word location 0000AH.
•Interrupt flag and trap flag are reset to 0.

INTR
The INTR is a maskable interrupt because the microprocessor will be interrupted only if
interrupts are enabled using set interrupt flag instruction. It should not be enabled
using clear interrupt Flag instruction.
The INTR interrupt is activated by an I/O port. If the interrupt is enabled and NMI is
disabled, then the microprocessor first completes the current execution and sends ‘0’
on INTA pin twice. The first ‘0’ means INTA informs the external device to get ready
and during the second ‘0’ the microprocessor receives the 8 bit, say X, from the
programmable interrupt controller.
These actions are taken by the microprocessor
•First completes the current instruction.
•Activates INTA output and receives the interrupt type, say X.
•Flag register value, CS value of the return address and IP value of the return address
are pushed on to the stack.
•IP value is loaded from the contents of word location X × 4
CS is loaded from the contents of the next word location.
Interrupt flag and trap flag is reset to 0

Software Interrupts
Some instructions are inserted at the desired position into the program to create
interrupts. These interrupt instructions can be used to test the working of various
interrupt handlers.
It includes
INT- Interrupt instruction with type number like int 06
It is 2-byte instruction. First byte provides the op-code and the second byte provides the
interrupt type number. There are 256 interrupt types under this group.
Its execution includes the following steps
•Flag register value is pushed on to the stack.
•CS value of the return address and IP value of the return address are pushed on to the
stack.
•IP is loaded from the contents of the word location ‘type number’ × 4
•CS is loaded from the contents of the next word location.
•Interrupt Flag and Trap Flag are reset to 0

Interrupts of 8086
The starting address for type0 interrupt is 00000H, for type1 interrupt is 00004H
similarly for type2 is 00008H and ……so on. The first five pointers are dedicated
interrupt pointers. i.e.
•TYPE 0 interrupt represents division by zero situation.
•TYPE 1 interrupt represents single-step execution during the debugging of a
program.
•TYPE 2 interrupt represents non-maskable NMI interrupt.
•TYPE 3 interrupt represents break-point interrupt.
•TYPE 4 interrupt represents overflow interrupt.
The interrupts from Type 5 to Type 31 are reserved for other advanced
microprocessors, and interrupts from 32 to Type 255 are available for hardware
and software interrupts.

Interrupts of 8086
INT 3-Break Point Interrupt Instruction
It is a 1-byte instruction having op-code is CCH. These instructions are inserted into the
program so that when the processor reaches there, then it stops the normal execution of
program and follows the break-point procedure.
•Flag register value is pushed on to the stack.
•CS value of the return address and IP value of the return address are pushed on to the
stack.
•IP is loaded from the contents of the word location 3×4 = 0000CH
•Interrupt Flag and Trap Flag are reset to 0
INTO - Interrupt on overflow instruction
It is a 1-byte instruction and their mnemonic INTO. The op-code for this instruction is CEH.
As the name suggests it is a conditional interrupt instruction, i.e. it is active only when the
overflow flag is set to 1 and branches to the interrupt handler whose interrupt type
number is 4. If the overflow flag is reset then, the execution continues to the next
instruction.

Interrupts of 8086
•Flag register values are pushed on to the stack.
•CS value of the return address and IP value of the return address are pushed
on to the stack.
•IP is loaded from the contents of word location 4×4 = 00010H
•Interrupt flag and Trap flag are reset to 0

8259 interrupt controller
The Block Diagram consists of 8 blocks which are – Data Bus Buffer,
Read/Write Logic, Cascade Buffer Comparator, Control Logic, Priority Resolver
and 3 registers- ISR, IRR, IMR.
Data bus buffer
This Block is used as a mediator between 8259 and 8086 microprocessor by
acting as a buffer. It takes the control word from the 8086 microprocessor
and transfer it to the control logic of 8259 microprocessor. Also, after
selection of Interrupt by 8259 microprocessor, it transfer the opcode of the
selected Interrupt and address of the Interrupt service sub routine to the
connected microprocessor. The data bus buffer consists of 8 bits represented
as D0-D7 in the block diagram. Thus, shows that a maximum of 8 bits data
can be transferred at a time.
Read/Write logic
This block works only when the value of pin CS is low (as this pin is active
low). This block is responsible for the flow of data depending upon the inputs
of RD and WR. These two pins are active low pins used for read and write
operations.

Control logic : It is the centre of the microprocessor and controls the functioning of every
block. It has pin INTR which is connected with other microprocessor for taking interrupt
request and pin INT for giving the output. If 8259 is enabled, and the other microprocessor
Interrupt flag is high then this causes the value of the output INT pin high and in this way
8259 responds to the request made by other microprocessor.
Interrupt request register (IRR) : It stores all the interrupt level which are requesting for
Interrupt services.
Interrupt service register (ISR) : It stores the interrupt level which are currently being
executed.
Interrupt mask register (IMR) : It stores the interrupt level which have to be masked by
storing the masking bits of the interrupt level.

Priority resolver :
It examines all the three registers and set the priority of interrupts and
according to the priority of the interrupts, interrupt with highest priority is set
in ISR register. Also, it reset the interrupt level which is already been serviced in
IRR.
Cascade buffer :
To increase the Interrupt handling capability, cascading is done for more
number of pins by using cascade buffer. So, during increment of interrupt
capability, CSA lines are used to control multiple interrupt structure.
SP/EN (Slave program/Enable buffer) pin is when set to high, works in master
mode else in slave mode. In Non Buffered mode, SP/EN pin is used to specify
whether 8259 work as master or slave and in Buffered mode, SP/EN pin is used
as an output to enable data bus.

8259 Interrupt Controller
Features of 8259 PIC microprocessor –
Intel 8259 is designed for Intel 8085 and Intel 8086 microprocessor.
It can be programmed either in level triggered or in edge triggered interrupt level.
We can masked individual bits of interrupt request register.
We can increase interrupt handling capability upto 64 interrupt level by cascading
further 8259 PIC.
Clock cycle is not required.

Control words of 8259
Command word of 8259 is divided into two parts :
Initialization command words(ICW)
Operating command words(OCW)
Initialization command words(ICW) :
ICW is given during the initialization of 8259
ICW1 and ICW2 commands are compulsory for initialization.
ICW3 command is given during a cascaded configuration.
If ICW4 is needed, then it is specified in ICW1.
The sequence order of giving ICW commands is fixed i.e. ICW1 is given first and then
ICW2 and then ICW3.
Any of the ICW commands can not be repeated, but the entire initialization process can
be repeated if required.
Operating command words(OCW) :
OCW is given during the operation of 8259 i.e. microprocessor starts using 8259.
OCW commands are not compulsory for 8259.
The sequence order of giving OCW commands is not fixed.
The OCW commands can be repeated.

When the ICW1 is loaded, then the initializations performed are:
The edge sense circuit is reset because, by default, 8259 interrupt is edge triggered.
The interrupt mask register is cleared.
IR7 is assigned to priority 7.
Slave mode address is assigned as 7.
When D0 = 0, this means IC4 command is not required. Therefore, functions used in IC4
are reset.
Special mask mode is reset and status read is assigned to IRR.
ICW2 command :
The control word is recognized as ICW2 when A0= 1.
It stores the information regarding the interrupt vector address.
In the 8085 based system, the A15 to A8 bits of control word is used for interrupt vector
addresses.
In the 8086 based system, T6 to T3 bits are inserted instead of A15 to A8 and A10 to A8 are
used for selecting interrupt level, i.e. 000 for IR0 and 111 for IR7.

8259 Operational command word
Operational command word 1
It is used to set and reset the mask bits in IMR(interrupt mask register). M7 –
M0 describes 8 mask bits

Direct Memory Access (DMA)
DMA Controller is a hardware device that allows I/O devices to directly access
memory with less participation of the processor.
DMA controller needs the same old circuits of an interface to communicate with
the CPU and Input/ Output devices.
The unit communicates with the CPU through data bus and control lines.
Through the use of the address bus and allowing the DMA and RS register to select
inputs, the register within the DMA is chosen by the CPU.
RD and WR are two-way inputs.
When BG (bus grant) input is 0, the CPU can communicate with DMA registers.
When BG (bus grant) input is 1, the CPU has relinquished the buses and DMA can
communicate directly with the memory.

DMA registers
•Address register – It contains the address to
specify the desired location in memory.
•Word count register – It contains the number of
words to be transferred.
•Control register – It specifies the transfer mode.
All registers in the DMA appear to the CPU as I/O
interface registers. Therefore, the CPU can both
read and write into the DMA registers under
program control via the data bus.

Serial communication
Serial communication is a communication method that uses one or two transmission lines
to send and receive data, and that data is continuously sent and received one bit at a time.
Since it allows for connections with few signal wires, one of its merits is its ability to hold
down on wiring material and relaying equipment costs.
Serial communication standards
RS-232C/RS-422A/RS-485 are EIA (Electronic Industries Association) communication
standards. Of these communication standards, RS-232C has been widely adopted in a
variety of applications, and it is even standard equipment on computers and is often used
to connect modems and mice. Sensors and actuators also contain these interfaces, many
of which can be controlled via serial communication.

Single-ended signaling is the simplest and most commonly used method of
transmitting electrical signals over wires.
One wire carries a varying voltage that represents the signal, while the other wire is
connected to a reference voltage, usually ground.
Differential signaling is a method for electrically transmitting information using two
complementary signals.
The technique sends the same electrical signal as a differential pair of signals, each in
its own conductor.
The pair of conductors can be wires in a twisted-pair or ribbon cable or traces on
a printed circuit board.

RS-232C
This serial communication standard is widely used and is often equipped on
computers as standard.It is also called "EIA-232".The purpose and timing of the signal
lines and the connectors have been defined (D-sub 25-pin or D-sub 9-pin).Currently
the standard has been revised with the addition of signal lines and is formally called
"ANSI/EIA-232-E".However, even now it is generally referred to as "RS-232C".
RS-422A
This standard fixes problems in RS-232C such as a short transmission distance and a
slow transmission speed.It is also called "EIA-422A".The purpose and timing of the
signal lines are defined, but the connectors are not.Many compatible products
primarily adopt D-sub 25-pin and D-sub 9-pin connectors.
RS-485
This standard fixes the problem of few connected devices in RS-422A.It is also called
"EIA-485".RS-485 is forward compatible standard with RS-422A.The purpose and
timing of the signal lines are defined, but the connectors are not.Many compatible
products primarily adopt D-sub 25-pin and D-sub 9-pin connectors

In RS-232C, the connectors to use and the signal assignments have been defined
and are standardized. The figure to the right describes the D-sub 9-pin signal
assignments and signal lines.
Pin No. Signal name Description
1 DCD Data Carrier Detect Carrier detect
2 RxD Received Data Received data
3 TxD Transmitted Data Transmitted data
4 DTR Data Terminal Ready Data terminal ready
5 SG Signal Ground
Signal ground or
common return
6 DSR Data Set Ready Data set ready
7 RTS Request To Send Request to send
8 CTS Clear To Send Clear to send
9 RI Ring Indicator Ring indicator
CASE FG Frame Ground
Maintenance ground or
earth

RS 232 Connection method
In RS-232C, the connectors and signal assignments have been standardized, so many
standard-compliant cables are available commercially. However, equipment comes in the
following types, and depending on the equipment that will be connected, a straight
cable or a crossover cable is required.
Equipment type
DCE
Data communication equipment.This term indicates equipment that passively operates
such as modems, printers, and plotters.
DTE
Data terminal equipment.This term indicates equipment that actively operates such as
computers.
Full-duplex communication
A method where send and receive both have their own transmission line so data can
be simultaneously sent and received.
Half-duplex communication
A method where communication is performed using one transmission line while
switching between send and receive. For this reason, simultaneous communication
cannot be performed.

Crossover cable connection
Full-duplex communication A method where send and receive both have their
own transmission line so data can be simultaneously sent and received. Half-
duplex communication A method where communication is performed using one
transmission line while switching between send and receive. For this reason,
simultaneous communication cannot be performed

Serial Data transfer schemes
Serial communication transmits data one bit at a time, sequentially, over a single
communication line to a receiver.
Serial is also a most popular communication protocol that is used by many devices for
instrumentation.
This method is used when data transfer rates are very low or the data must be
transferred over long distances and also where the cost of cable and synchronization
difficulties makes parallel communication impractical. Serial communication is popular
because most

Synchronous data transmission
The synchronous signaling methods use two different signals. A pulse on one signal
line indicates when another bit of information is ready on the other signal line.
In synchronous transmission, the stream of data to be transferred is encoded and sent
on one line, and a periodic pulse of voltage which is often called the "clock" is put on
another line, that tells the receiver about the beginning and the ending of each bit.

UART BLOCK DIAGRAM
The UART full form is “Universal Asynchronous Receiver/Transmitter”, and it is an inbuilt IC
within a microcontroller but not like a communication protocol (I2C & SPI). The main
function of UART is to serial data communication.
In UART, the communication between two devices can be done in two ways namely serial
data communication and parallel data communication.

The asynchronous signaling methods use only one signal. The receiver uses
transitions on that signal to figure out the transmitter bit rate (known as auto
baud) and timing.
A pulse from the local clock indicates when another bit is ready. That means
synchronous transmissions use an external clock, while asynchronous
transmissions use special signals along the transmission medium.
Asynchronous communication is the commonly prevailing communication
method in the personal computer industry, due to the reason that it is easier to
implement and has the unique advantage that bytes can be sent whenever
they are ready, a no need to wait for blocks of data to accumulate.

Asynchronous data transmission

THANK YOU
COURSE: DCN UNIT:1 Pg.91

Lecture 2
The 8051 Microcontroller architecture

Contents:
Introduction
Block Diagram and Pin Description of the 8051
Registers
Some Simple Instructions
Structure of Assembly language and Running
an 8051 program
Memory mapping in 8051
8051 Flag bits and the PSW register
Addressing Modes
16-bit, BCD and Signed Arithmetic in 8051
Stack in the 8051
LOOP and JUMP Instructions
CALL Instructions
I/O Port Programming

1. meeting the computing needs of the task efficiently and cost
effectively
• speed, the amount of ROM and RAM, the number of I/O ports
and timers, size, packaging, power consumption
• easy to upgrade
• cost per unit
2. availability of software development tools
• assemblers, debuggers, C compilers, emulator, simulator,
technical support
3. wide availability and reliable sources of the microcontrollers.
Three criteria in Choosing a Microcontroller

The 8051 microcontroller
 a Harvard architecture (separate instruction/data
memories)
 single chip microcontroller (µC)
 developed by Intel in 1980 for use in embedded
systems.
 today largely superseded by a vast range of faster
and/or functionally enhanced 8051-compatible
devices manufactured by more than 20
independent manufacturers

Block Diagram
CPU
On-chip
RAM
On-chip
ROM for
program
code
4 I/O Ports
Timer 0
Serial
Port
OSC
Interrupt
Control
External interrupts
Timer 1
Timer/
Counter
Bus
Control
TxD RxD
P0 P1 P2 P3
Address/Data
Counter
Inputs

Feature 8051 8052 8031
ROM (program space in bytes) 4K 8K 0K
RAM (bytes) 128 256 128
Timers 2 3 2
I/O pins 32 32 32
Serial port 1 1 1
Interrupt sources 6 8 6
Comparison of the 8051 Family Members

Pin Description of the 8051
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
RST
(RXD)P3.0
(TXD)P3.1
(T0)P3.4
(T1)P3.5
XTAL2
XTAL1
GND
(INT0)P3.2
(INT1)P3.3
(RD)P3.7
(WR)P3.6
Vcc
P0.0(AD0)
P0.1(AD1)
P0.2(AD2)
P0.3(AD3)
P0.4(AD4)
P0.5(AD5)
P0.6(AD6)
P0.7(AD7)
EA/VPP
ALE/PROG
PSEN
P2.7(A15)
P2.6(A14)
P2.5(A13)
P2.4(A12)
P2.3(A11)
P2.2(A10)
P2.1(A9)
P2.0(A8)
8051
(8031)


Pins of 8051（1/4）
 Vcc（pin 40）：
 Vcc provides supply voltage to the chip.
 The voltage source is +5V.
 GND（pin 20）：ground
 XTAL1 and XTAL2（pins 19,18）：
 These 2 pins provide external clock.
 Way 1：using a quartz crystal oscillator
 Way 2：using a TTL oscillator
 Example 4-1 shows the relationship between XTAL
and the machine cycle.

Pins of 8051（2/4）
 RST（pin 9）：reset
 It is an input pin and is active high（normally low）.
 The high pulse must be high at least 2 machine cycles.
 It is a power-on reset.
 Upon applying a high pulse to RST, the microcontroller will
reset and all values in registers will be lost.
 Reset values of some 8051 registers
 Way 1：Power-on reset circuit
 Way 2：Power-on reset with debounce

Pins of 8051（3/4）
 /EA（pin 31）：external access
 There is no on-chip ROM in 8031 and 8032 .
 The /EA pin is connected to GND to indicate the code is stored
externally.
 /PSEN ＆ ALE are used for external ROM.
 For 8051, /EA pin is connected to Vcc.
 “/” means active low.
 /PSEN（pin 29）：program store enable
 This is an output pin and is connected to the OE pin of the ROM.
 See Chapter 14.

Pins of 8051（4/4）
 ALE（pin 30）：address latch enable
 It is an output pin and is active high.
 8051 port 0 provides both address and data.
 The ALE pin is used for de-multiplexing the address and data by
connecting to the G pin of the 74LS373 latch.
 I/O port pins
 The four ports P0, P1, P2, and P3.
 Each port uses 8 pins.
 All I/O pins are bi-directional.

Figure 4-2 (a). XTAL Connection to 8051
XTAL1
 Using a quartz crystal oscillator
 We can observe the frequency on the XTAL2 pin.


Figure 4-2 (b). XTAL Connection to an External Clock
Source
N
C
EXTERNAL
OSCILLATOR
SIGNAL
XTAL2
XTAL1
GND
 Using a TTL oscillator
 XTAL2 is unconnected.


RESET Value of Some 8051 Registers:
0000
DPTR
0007
SP
0000
PSW
0000
B
0000
ACC
0000
PC
Reset Value
Register
RAM are all zero.


Figure 4-3 (a). Power-On RESET Circuit
30 pF
30 pF
8.2 K
10 uF
+
Vcc
11.0592 MHz
EA/VPP
X1
X2
RST
31
19
18
9


Figure 4-3 (b). Power-On RESET with Debounce
EA/VPP
X1
X2
RST
Vcc
10 uF
8.2 K
30 pF
9
31


Pins of I/O Port
 The 8051 has four I/O ports
 Port 0 （pins 32-39）：P0（P0.0～P0.7）
 Port 1（pins 1-8）：P1（P1.0～P1.7）
 Port 2（pins 21-28）：P2（P2.0～P2.7）
 Port 3（pins 10-17）：P3（P3.0～P3.7）
 Each port has 8 pins.
 Named P0.X （X=0,1,...,7）, P1.X, P2.X, P3.X
 Ex：P0.0 is the bit 0（LSB）of P0
 Ex：P0.7 is the bit 7（MSB）of P0
 These 8 bits form a byte.
 Each port can be used as input or output (bi-direction).


Registers
A
B
R0
R1
R3
R4
R2
R5
R7
R6
DPH DPL
PC
DPTR
PC
Some 8051 16-bit Register
Some 8-bitt Registers of
the 8051

CPU timing
 Most 8051 instructions are executed in one cycle.
 MUL (multiply) and DIV (divide) are the only
 instructions that take more than two cycles to complete (four
cycles)
 Normally two code bytes are fetched from the program memory
during every machine cycle.
 The only exception to this is when a MOVX instruction is
executed. MOVX is a one-byte, 2-cycle instruction that accesses
external data memory.
 During a MOVX, the two fetches in the second cycle are
skipped while the external data memory is being addressed and
strobed.

Example :

Find the machine cycle for
(a) XTAL = 11.0592 MHz
(b) XTAL = 16 MHz.
Solution:
(a) 11.0592 MHz / 12 = 921.6 kHz;
machine cycle = 1 / 921.6 kHz = 1.085 s
(b) 16 MHz / 12 = 1.333 MHz;
machine cycle = 1 / 1.333 MHz = 0.75 s

Timers
 8051 has two 16-bit on-chip timers that can be
used for timing durations or for counting
external events
 The high byte for timer 1 (TH1) is at address
8DH while the low byte (TL1) is at 8BH
 The high byte for timer 0 (TH0) is at 8CH while
the low byte (TL0) is at 8AH.
 Timer Mode Register (TMOD) is at address
88H

Timer Mode Register
 Bit 7: Gate bit; when set, timer only runs while INT high.
(T0)
 Bit 6: Counter/timer select bit; when set timer is an event
counter when cleared timer is an interval timer (T0)
 Bit 5: Mode bit 1 (T0)
 Bit 3: Gate bit; when set, timer only runs while INT high.
(T1)
 Bit 2: Counter/timer select bit; when set timer is an event
counter when cleared timer is an interval timer (T1)

Timer Modes
 M1-M0: 00 (Mode 0) – 13-bit mode (not
commonly used)
 M1-M0: 01 (Mode 1) - 16-bit timer mode
 M1-M0: 10 (Mode 2) - 8-bit auto-reload mode
 M1-M0: 11 (Mode 3) – Split timer mode

The Stack and Stack Pointer
 The Stack Pointer, like all registers except DPTR and PC, may hold an 8-bit (1-byte)
value.
 The Stack Pointer is used to indicate where the next value to be removed from the
stack should be taken from.
 When you push a value onto the stack, the 8051 first increments the value of SP and
then stores the value at the resulting memory location.
 When you pop a value off the stack, the 8051 returns the value from the memory
location indicated by SP, and then decrements the value of SP.
 This order of operation is important. When the 8051 is initialized SP will be initialized
to 07h. If you immediately push a value onto the stack, the value will be stored in
Internal RAM address 08h. This makes sense taking into account what was mentioned
two paragraphs above: First the 8051 will increment the value of SP (from 07h to 08h)
and then will store the pushed value at that memory address (08h).
 SP is modified directly by the 8051 by six instructions: PUSH, POP, ACALL, LCALL,
RET, and RETI. It is also used intrinsically whenever an interrupt is triggered

PREPARED BY
SUBJECT NAME: DIGITAL COMPUTE PLATFORMS
UNIT : IV
:
C.MUNIKANTHA

OUTLINE – UNIT-1
Introduction to the TMS320LF2407 DSP Controller
Basic architectural features
Physical Memory
Software Tools.
Introduction to Interrupts
interrupt Hierarchy
Interrupt Control Registers.
C2xx DSP CPU
Instruction Set:
Introduction & code Generation
Components of the C2xx DSP core
Mapping External Devices to the C2xx core
peripheral interface - system configuration registers
Memory
Memory Addressing Modes
Assembly Programming Using the C2xx DSP Instruction set.

A TMS 320 C 6713 DSP operating at 225 MHz.
• 16 Mbytes of synchronous DRAM
• 512 Kbytes of non-volatile Flash memory
• (256 Kbytes usable in default conguration)
• 4 user accessible LEDs and DIP switches
• Software board conguration through
• registers implemented in CPLD ACOE 343 - Embedded
Real-Time Processor Systems

Differences between DSP and Microcontroller

TMS320LF2407 DSP Controller functional diagram

TMS320LF2407 DSP Controller functional diagram 1/2

TMS320LF2407 DSP Controller functional diagram 2/2

TMS320LF2407 DSP Controller
It is a C2xx core CPU for low-cost, low-power, and high-performance processing
capabilities.
Several advanced peripherals, optimized for digital motor and motion control
applications, have been integrated to provide a true single-chip DSP controller.
The 240xA offers increased processing performance (40 MIPS) and a higher level of
peripheral integration.
Flash devices of up to 32K words offer a cost-effective reprogrammable solution for
volume production.
The 240xA devices offer a password-based “code security” feature which is useful in
preventing unauthorized duplication of proprietary code stored in on-chip Flash/ROM.
The 240xA family also includes ROM devices.
All 240xA devices offer at least one event manager module which has been optimized for
digital motor control and power conversion applications.
Capabilities of this module include center- and/or edge-aligned PWM generation.

It prevent shoot-through faults, and synchronized analog-to-digital conversion. Devices
with dual event managers enable multiple motor and/or converter control with a single
240xA DSP controller.
The high-performance, 10-bit analog-to-digital converter (ADC) has a minimum
conversion time of 375 ns and offers up to 16 channels of analog input.
A serial communications interface (SCI) is integrated on all devices to provide
asynchronous communication to other devices in the system.
It offer a controller area network (CAN) communications module.
JTAG-compliant scan-based emulation has been integrated into all devices.
A complete suite of code-generation tools from C compilers to the industry-standard
Code Composer Studio debugger supports this family.
It is a member of the C2000 platform of fixed point DSPs.
The C3x and C4x floating-point DSPs

The LF2407A combines the high-performance CPU core with a set of peripherals acting
as the “heavy artillery” to meet interfacing requirements for the most demanding of
problems in terms of digital signal processing, communications and general purpose I/O
operations.
The Event Managers, incorporating Timers and PWM generators.
The Controller Area Network (CAN) Module.
The Analog to Digital Converter.
The Serial Peripheral Interface (SPI) for synchronous serial communications.
The Serial Communications Interface (SCI) - asynchronous serial port (universal
asynchronous receiver and transmitter − UART).
The Watchdog timer.
General bi-directional digital I/O (GPIO) pins.
the peripherals commonly employed are the event managers and the ADC.

The event managers.
These peripherals include a set of modules to facilitate creation of pulse width modulated
signals and capture rising/falling edges in pulses.
In the “heart” of the event managers, lie the general purpose timers, providing clocking
to the modules of the device; they may also be used to synchronize the occurrence of
events in our programs.
The event managers are highly configurable to the last detail, with an extensive list of
configuration/control registers.
The CAN module.
The controller area network module implements the multi-master CAN bus
communications protocol interface with a set of six mailboxes.

The Analog to Digital Converter.
The ADC is used to sample analog signals and produce the corresponding digital value
stored in a 10-bit integer result.
Arguably, it is one of the most significant peripherals on the LF2407A. It utilizes two
sequencers as finite state machines that synchronize the sampling process.
The Serial Peripheral Interface.
The SPI is used for synchronous master-slave high speed serial communications. Typically,
the SPI is used for communications with external devices such as LCDs and Digital to
Analog Converters.
The Serial Communications Interface. The SCI implements typical asynchronous serial
communications (UART). Typical applications of the SCI include communications with
other controllers, or a PC. The designated lines for reception (RX) and transmission (TX)
are not level-shifted on the DSP board (i.e., they operate at 0-3.3V).

The Watchdog Timer.
The watchdog is essentially a timer, acting as a safety precaution
against possible program locks in endless loops.
When enabled, the watchdog increases an internal 8-bit counter using a clocking signal
running at a sub-multiple frequency of the CPU clock signal.
The program should be able to reset the counter before an overflow occurs; if, for any
reason (which may possibly be an execution “hung”), the program fails to reset the
watchdog in time, the counter will overflow and a system reset will be asserted.
The General bi-directional I/O pins.
The LF2407A has a set of general I/O pins organized in ports A, B, C, D, E and F.
Most of the I/O pins on the LF2407A are multiplexed with other devices (e.g., general I/O
pin A6 is multiplexed with the PWM1 pin) and must be configured prior to use, either for
their primary (non - general I/O) or secondary (general I/O) function.
Moreover, general I/O pins can be configured either as input or output.

The ’C24x DSP controllers are designed to meet the needs of control-based applications.
• By integrating the high performance of a DSP core and the on-chip peripherals of a
microcontroller into a single-chip solution, the ’C24x series yields a device that is an
affordable alternative to traditional microcontroller units (MCUs) and expensive multichip
designs.
• At 20 million instructions per second (MIPS), the ’C24x DSP controllers offer significant
performance over traditional 16-bit microcontrollers and microprocessors.
• The 16-bit, fixed-point DSP core of the ’C24x device provides analog designers a digital
solution that does not sacrifice the precision and performance of their systems. The ’C24x
DSP controllers offer reliability and programmability. Analog control systems, on the
other hand, are hardwired solutions and can experience performance degradation due to
aging, component tolerance, and drift.
• The high-speed central processing unit (CPU) allows the digital designer to process
algorithms in real time rather than approximate results with look-up tables
• The ’C24x architecture is also well-suited for processing control signals.
• It uses a 16-bit word length along with 32-bit registers for storing intermediate results,
and has two hardware shifters available to scale numbers independently of the CPU. This
combination minimizes quantization and truncation errors, and increases processing
power for additional functions. Two examples of these additional functions are: a notch
filter that cancels mechanical resonances in a system, and an estimation technique that
eliminates state sensors in a system

TMS320C24x Nomenclature
TMS – stands for qualified device
320 - TMS320 Family
C – CMOS technology
24x - device

C24x CPU Internal Bus Structure
C24x CPU Internal Bus Structure
The ’C24x DSP, a member of the TMS320 family of DSPs, includes a ’C2xx DSP core
designed using the ’2xLP ASIC core.
The ’C2xx DSP core has an internal data and program bus structure that is divided into six
16-bit buses.
The six buses are:
• PAB. The program address bus provides addresses for both reads from and writes to
program memory.
• DRAB. The data-read address bus provides addresses for reads from data memory.
• DWAB. The data-write address bus provides addresses for writes to data memory.
• PRDB. The program read bus carries instruction code and immediate operands, as well
as table information, from program memory to the CPU.
• DRDB. The data-read bus carries data from data memory to the central arithmetic logic
unit (CALU) and the auxiliary register arithmetic unit (ARAU).
• DWEB. The data-write bus carries data to both program memory and data memory.
Having separate address buses for data reads (DRAB) and data writes (DWAB) allows the
CPU to read and write in the same machine cycle.

The ’C24x contains the following types of on-chip memory:
• Dual-access RAM (DARAM)
• Flash EEPROM or ROM (masked) The ’C24x memory is organized into four individually-
selectable spaces:
• Program (64K words)
• Local data (64K words)
• Global data (32K words)
• Input/Output (64K words) These spaces form an address range of 224K words.

On-Chip Dual-Access RAM (DARAM)
• The ’C24x has 544 words of on-chip DARAM, which can be accessed twice per machine
cycle. This memory is primarily intended to hold data, but when needed, can also be used
to hold programs.
• The memory can be configured in one of two ways, depending on the state of the CNF
bit in status register ST1. → When CNF = 0, all 544 words are configured as data memory.
→ When CNF = 1, 288 words are configured as data memory and 256 words are
configured as program memory.
• Because DARAM can be accessed twice per cycle, it improves the speed of the CPU.
• The CPU operates within a 4-cycle pipeline. In this pipeline, the CPU reads data on the
third cycle and writes data on the fourth cycle.
However, DARAM allows the CPU to write and read in one cycle; the CPU writes to DARAM
on the master phase of the cycle and reads from DARAM on the slave phase.
For example, suppose two instructions, A and B, store the accumulator value to DARAM
and load the accumulator with a new value from DARAM. Instruction A stores the
accumulator value during the master phase of the CPU cycle, and instruction B loads the
new value in the accumulator during the slave phase. Because part of the dual-access
operation is a write, it only applies to RAM.

Flash EEPROM
•Flash EEPROM provides an attractive alternative to masked program ROM
. • Like ROM, flash is a nonvolatile memory type; however, it has the advantage of in-
target reprogrammability.
• The ’F24x incorporates one 16K/8K × 16-bit flash EEPROM module in program space.
• This type of memory expands the capabilities of the ’F24x in the areas of prototyping,
early field testing, and single-chip applications.
• Unlike most discrete flash memory, the ’F24x flash does not require a dedicated state
machine because the algorithms for programming and erasing the flash are executed by
the DSP core. This enables several advantages, including reduced chip size and
sophisticated adaptive algorithms..
• Other key features of the flash include zero-wait-state access rate and single 5-V power
supply. The following four algorithms are required for flash operations:
• clear, erase, flash-write, and program.

External Memory Interface Module
•In addition to full, on-chip memory support, some of the ’C24x devices provide
access to external memory by way of the External Memory Interface Module.
• This interface provides 16 external address lines, 16 external data lines, and
relevant control signals to select data, program, and I/O spaces. An on-chip wait-
state generator allows interfacing with slower off-chip memory and peripherals.

Central Processing Unit
A 32-bit central arithmetic logic unit (CALU)
• A 32-bit accumulator
• Input and output data-scaling shifters for the CALU
• A 16-bit × 16-bit multiplier
• A product-scaling shifter
• Data-address generation logic, which includes eight auxiliary registers and an
auxiliary register arithmetic unit (ARAU)
• Program-address generation logic

Input Scaling Section
A 32-bit input data-scaling shifter (input shifter) aligns the 16-bit value from memory to
the 32- bit central arithmetic logic unit (CALU).
This data alignment is necessary for data-scaling arithmetic, as well as aligning masks for
logical operations.
The input shifter operates as part of the data path between program or data space and
the CALU; and therefore, requires no cycle overhead.
Input. Bits 15 through 0 of the input shifter accept a 16-bit input from either of two
The data read bus (DRDB). This input is a value from a data memory location referenced
in an instruction operand.
The program read bus (PRDB). This input is a constant value given as an instruction
operand. Output. After a value has been accepted into bits 15 through 0, the input shifter
aligns the16-bit value to the 32-bit bus of the CALU
The shifter shifts the value left 0 to 16 bits and then sends the 32-bit result to the CALU.

Multiplication Section
The ’C24x uses a 16-bit × 16-bit hardware multiplier that can produce a signed or
unsigned 32-bit product in a single machine cycle.
The multiplication section consists of:
The 16-bit temporary register (TREG), which holds one of the multiplicands
The multiplier, which multiplies the TREG value by a second value from data memory
or program memory .
The 32-bit product register (PREG), which receives the result of the multiplication
The product shifter, which scales the PREG value before passing it to the CALU

Multiplier
The 16-bit × 16-bit hardware multiplier can produce a signed or unsigned 32-bit product
in a single machine cycle.
The two numbers being multiplied are treated as 2s-complement numbers, except
during unsigned multiplication (MPYU instruction).
Descriptions of the inputs to, and output of, the multiplier
Inputs. The multiplier accepts two 16-bit inputs:
One input is always from the 16-bit temporary register (TREG). The TREG is loaded
before the multiplication with a data-value from the data read bus (DRDB).
The other input is one of the following: _ A data-memory value from the data read bus
(DRDB) _ A program memory value from the program read bus (PRDB) Output.
After the two 16-bit inputs are multiplied, the 32-bit result is stored in the product
register (PREG).
The output of the PREG is connected to the 32-bit product-scaling shifter.
Through this shifter, the product is transferred from the PREG to the CALU or to data
memory (by the SPH and SPL instructions).

Interrupts
The ’C24x DSP supports both hardware and software interrupts.
The hardware interrupts INT1 – INT6, along with NMI, TRAP, and RS, provide a flexible
interrrupt scheme.
The software interrupts offer flexibility to access interrupt vectors using software
instructions.
Since most of the ’C24x DSPs come with multiple peripherals, the core interrupts (INT1–
IN6) are expanded using additional system or peripheral interrupt logic.
Although the core interrupts are the same, the peripheral interrupt structure varies
slightly among ’C240 and ’C24x class of DSP controllers.
CPU Interrupt Registers
There are two CPU registers for controlling interrupts:
The interrupt flag register (IFR) contains flag bits that indicate when maskable interrupt
requests have reached the CPU on levels INT1 through INT6.
The interrupt mask register (IMR) contains mask bits that enable or disable each of the
interrupt levels (INT1 through INT6).

The Reset interrupt Vector
If no boot ROM is present, then, following a reset, the DSP loads address 0x0000
(program memory) to the instruction pointer.
Address 0x0000 is the location for the reset vector and it should contain a branching
instruction (jump) to whatever you want the DSP to do immediately after reset.

The LF2407A Core Interrupts .
The 2407A is capable of six (6) maskable interrupts and several software (TRAPS) and
non-maskable interrupts (NMI). Practically, code will be dealing with the six maskable
core interrupts (INT1-6), with the extreme exception of the occasional use of software
interrupts.
The first 6 interrupts (except INT0 which is the reset interrupt vector) correspond
to the peripherals of the 2407A through a peripheral interrupt expansion controller (will
be discussed later), and it is important that the branching instructions in “cvectors.asm”
are pointing to the appropriate interrupt service routines (ISR) implemented in the C
code.

INTERRUPTS
Interrupts are special events, normally triggered by external sources involving
Peripherals.
you may choose to “interrupt” the sequential flow of execution and branch code
execution to a special function that handles the event that triggered the interrupt. The
special routines that handle interrupt signals are usually called interrupt handlers, but
you will find the term interrupt service routines (ISR) rather more commonly used.
The 2407A is able to “sense” numerous interrupt sources, mainly related to its
peripherals.

The Peripheral Interrupt Expansion Controller (PIE)
The 2407A acknowledges interrupts in two levels. The core itself provides six maskable
interrupts (INT1-6). Technically, each of those interrupts may correspond to one specific
source. When programming interrupts for a PC, we know that there is a one-to-one
mapping from a peripheral interrupt source to a core interrupt in the CPU.
To overcome the problem of having a great number of hardware interrupts (as opposed
to the six available maskable core interrupts) to be served by the CPU, these interrupts
are organized in groups or levels, each one corresponding to one of the six core maskable
interrupts (INT1-6). This is actually where the peripheral interrupt expansion controller
(PIE) kicks-in. The PIE “intercepts” interrupt signals from the various peripherals and
consequently triggers the appropriate core interrupt.

Addressing Modes
The three modes are:
Immediate addressing mode
Direct addressing mode
Indirect addressing mode

Immediate addressing mode
In the immediate addressing mode, the instruction word contains a constant to be
manipulated by the instruction. The two types of immediate addressing modes are:
Short-immediate addressingInstructions that use short-immediate addressing have an 8-
bit, 9- bit, or 13-bit constant as an operand.
Ezxample.
RPT #99 ;Execute the instruction that follows RPT ;100 times.
Long-immediate addressing mode
Instructions that use long-immediate addressing have a 16-bit constant as an operand
and require two instruction words
ADD #16384,2 ;Shift the value 16384 left by two bits ;and add the result to the
accumulator.

Direct Addressing Mode
In the direct addressing mode, data memory is addressed in blocks of 128 words called
data pages. The entire 64K of data memory consists of 512 data pages labeled 0
through 511.
The current data page is determined by the value in the 9-bit data page pointer (DP) in
status register ST0.
For example, if the DP value is 0 0000 00002, the current data page is If the DP value is
0 0000 00102, the current data page is 2.

Indirect Addressing Mode
Eight auxiliary registers (AR0–AR7) provide flexible and powerful indirect addressing. Any
location in the 64K data memory space can be accessed using a 16-bit address contained
in an auxiliary register.
Indirect Addressing Options The ’C24x provides four types of indirect addressing options:
No increment or decrement. The instruction uses the content of the current auxiliary
register as the data memory address but neither increments nor decrements the content
of the current auxiliary register.
Increment or decrement by 1. The instruction uses the content of the current auxiliary
register as the data memory address and then increments or decrements the content of
the current auxiliary register by on.
Increment or decrement by an index amount.
The value in AR0 is the index amount. The instruction uses the content of the current
auxiliary register as the data memory address and then increments or decrements the
content of the current auxiliary register by the index amount.
The addition and subtraction process is accomplished with the carry propagation
reversed for fast Fourier transforms (FFTs).

Assembly Language Instructions
Instruction Set Summary
This section provides six tables (Table 7–1 to Table 7–6) that summarize the instruction
set according to the following functional headings:
Accumulator, arithmetic, and logic instructions Auxiliary register and data page pointer
instructions (see Table 7–2 on page 7-7)
TREG, PREG, and multiply instructions (see Table 7–3 on page 7-8)
Branch instructions (see Table 7–4 on page 7-9)
Control instructions (see Table 7–5 on page 7-10)
I/O and memory operations (see Table 7–6 on page 7-11)
definitions of the symbols used in the six summary tables:
ACC The accumulator AR The auxiliary register ARX A 3-bit value used in the LAR and
SAR instructions to designate which auxiliary register will be loaded (LAR) or have its
contents stored (SAR)
BITX A 4-bit value (called the bit code) that determines which bit of a designated data
memory value will be tested by the BIT instruction.
CM A 2-bit value. The CMPR instruction performs a comparison specified by the value of
CM:
If CM = 00, test whether current AR = AR0
If CM = 01, test whether current AR < AR0
If CM = 10, test whether current AR > AR0
If CM = 11, test whether current AR p AR0

Definitions of the symbols used in the six summary tables:
IAAA AAAA (One I followed by seven As)
The I at the left represents a bit that reflects whether direct addressing (I = 0) or
indirect addressing (I = 1) is being used.
When direct addressing is used, the seven As are the seven least significant bits (LSBs)
of a data memory address.
For indirect addressing, the seven As are bits that control auxiliary register
manipulation,
IIII IIII (Eight Is) An 8-bit constant used in short immediate addressing
I IIII IIII (Nine Is) A 9-bit constant used in short immediate addressing for the LDP
instruction
I IIII IIII IIII (Thirteen Is) A 13-bit constant used in short immediate addressing for the
MPY instruction.
I NTR# A 5-bit value representing a number from 0 to 31.
The INTR instruction uses this number to change program control to one of the 32
interrupt vector addresses.
PM A 2-bit value copied into the PM bits of status register ST1 by the SPM instruction
SHF A 3-bit left-shift value
SHFT A 4-bit left-shift value
TP A 2-bit value used by the conditional execution instructions to represent four
conditions
BIO pin low TP = 00
TC bit =1 TP = 01, TC bit = 0 TP = 10 and for No condition TP = 11

DIGITALRESOURCES
 Lecture Notes –
https://classroom.google.com/c/NDc1MzQ3NDk1MDM5/m/NDkzMzE5NzI0OTEz/details
 Vidéo Lectures –
watch?v=GapjjO_8Kuk

THANK YOU

PREPARED BY
SUBJECT NAME: DIGITAL COMPUTER PLATFORM
UNIT : V
: C MUNIKANTHA

OUTLINE
Introduction to Field Programmable Gate Arrays
CPLD Vs FPGA
Types of FPGA
Xilinx, XC3000 series
Configurable logic Blocks (CLB)
Input / Output Block (IOB)
Programmable Interconnect Point (PIP)
Xilinx 4000 series – HDL programming
overview of Spartan 3E and Virtex II pro FPGA boards- case
study

Field Programmable Gate Arrays
FPGA stands for Field Programmable Gate Array. It is a semiconductor
device that consists of a matrix of configurable logic blocks connected
using programmable interconnects. It is possible to reprogram an FPGA
according to the requirements after manufacturing. There are around
330000 logic blocks with 1100 inputs and outputs in modern FPGAs.

Programmable Logic Devices (PLD)
Programmable Logic Devices PLDs.
PLDs are the integrated circuits. They contain an array of AND gates & another array of
OR gates. There are three kinds of PLDs based on the type of arrays, which has
programmable feature.
Programmable Read Only Memory
Programmable Array Logic
Programmable Logic Array
The process of entering the information into these devices is known as programming.
Basically, users can program these devices or ICs electrically in order to implement the
Boolean functions based on the requirement. Here, the term programming refers to
hardware programming but not software programming.

Field Programmable Gate Arrays
The architecture of an FPGA is completely different as it consists of
programmable Logic Cells,
programmable interconnects
and programmable IO blocks.
Field Programmable Gate Arrays or FPGAs in short are pre-fabricated Silicon devices
that consists of a matrix of reconfigurable logic circuitry and programmable
interconnects arranged in a two-dimensional array.
The programmable Logic Cells can be configured to perform any digital function and
the programmable interconnects (or switches) provide the connections among
different logic cells.
Using an FPGA, you can implement any custom design by specifying the logic or
function of each logic block and setting the connection of each programmable switch.
Since this process of designing a custom circuit is done in the field rather than in a fab,
the device is known as “Field Programmable”.

An FPGA consists of three basic components. They are:
Programmable Logic Cells (or Logic Blocks) – responsible for implementing the core logic
functions.
Programmable Routing – responsible for connecting the Logic Blocks.
IO Blocks – which are connected to the Logic Blocks through the routing and help to make
external connections

PLA (Programmable logic array)

PAL (Programmable array logic)

CPLD versus FPGA
FPGAs and CPLDs are two of the well-known types of digital logic chips. When it comes to
the internal architecture, the two chips are obviously different.
FPGA is short for Field-Programmable Gate Array, is a type of a programmable logic chip.
It is great chip as it can be programmed to do almost any kind of digital function. FPGA’s
architecture allows the chip to have a very high logic capacity. It is used in designs that
require a high gate count and their delays are quite unpredictable because of
its architecture.
The FPGA is considered as ‘fine-grain’ because it contains a lot of tiny logic blocks that
could reach up to 100,000. It is with flip-flops, combination logic, and On the other hand,
CPLD (Complex Programmable Logic Device) is designed by using EEPROM (electrically
erasable programmable read-only memory) . It is more suitable in small gate count
designs. Since it is a less complex architecture, the delays are much predictable and it is
non-volatile.

CPLD versus FPGA
CPLD is often used for simple logic applications. It contains only a few blocks of logic and
reaches up to 100. Having said that, CPLDs are considered as ‘coarse-grain’ type of
devices. CPLDs are cheap and it also offers a much faster input to output duration
because of its simpler, ‘coarse grain’ architecture.
FPGAs are cheaper per gate but expensive when it comes to package.
Working with FPGAs requires special procedures as it is RAM based. To program the
device, you have to first describe the ‘logic function’ with the use of computer, either by
drawing a schematic or simply describing the function on a text file.
Compilation of the ‘logic function’ usually requires a software. It creates a binary file to
be downloaded into the FPGA and then the chip will behave just what you have
instructed in the ‘logic function’.

CPLD versus FPGA
1. FPGA contains up to 100,000 of tiny logic blocks while CPLD contains only a few blocks
of logic that reaches up to a few thousands.
2. In terms of architecture, FPGAs are considered as ‘fine-grain’ devices while CPLDs are
‘coarse-grain’.
3. FPGAs are great for more complex applications while CPLDs are better for simpler
ones.
4. FPGAs are made up of tiny logic blocks while CPLDs are made of larger blocks.
5. FPGA is a RAM-based digital logic chip while CPLD is EEPROM-based.
6. Normally, FPGAs are more expensive while CPLDs are much cheaper.
7. Delays are much more predictable in CPLDs than in FPGAs.

Types of FPGA
There are two basic types of FPGAs:
SRAM-based reprogrammable (Multi-time Programmed MTP)
and (One Time Programmed) OTP.
These two types of FPGAs differ in the implementation of the logic cell and the
mechanism used to make connections in the device.
The dominant type of FPGA is SRAM-based and can be reprogrammed as often. In fact, an
SRAM FPGA is reprogrammed every time it’s powered up, because the FPGA is really a
fancy memory chip. That’s why you need a serial PROM or system memory with every
SRAM FPGA

SRAM
A typical 6 transistor SRAM Cell to store 1 bit is shown in the following image.
SRAM is designed using transistors and the term static means that the value
loaded on a basic SRAM Memory Cell will remain the same until deliberately
changed or when the power is removed.

Types of FPGA
Property OTP FPGA MTP FPGA
Speed smaller larger
Power
Consumption
lower higher
Working
Environment
(Radiation)
Radiation hardened NO radiation
hardened
Design Cycle Programmed once
only
Many times
Price Almost the same Almost the same
Reliability More (single Chip) Less (2 Chips, FPGA
& PROM)
Security More secure Less secure

Xilinx,
Xilinx is the inventor of the FPGA, programmable SoCs, and now, the ACAP.
Xilinx delivers the most dynamic processing technology in the industry.
Xilinx, Inc. (/ˈzɪlɪŋks/ ZEE-links) was an American technology
and semiconductor company that primarily supplied programmable logic devices. The
company was known for inventing the first commercially viable field-programmable
gate array (FPGA) and creating the first fabless manufacturing model,
Xilinx was co-founded by Ross Freeman Bernard Vonderschmitt and James V Barnett II
in 1984 and the company went public on the NASDAQ in 1989.
AMD announced its acquisition of Xilinx in October 2020 and the deal was completed
on February 14, 2022 through an all-stock transaction worth an estimated $50 billion.
Before 2010, Xilinx offered two main FPGA families: the high-
performance Virtex series and the high-volume Spartan series, with a cheaper
EasyPath option for ramping to volume production.
The company also provides two CPLD lines: the CoolRunner and the 9500 series. Each
model series has been released in multiple generations since its launch. With the
introduction of its 28 nm FPGAs in June 2010, Xilinx replaced the high-volume Spartan
family with the Kintex family and the low-cost Artix family.

XC3000 series
Complete line of four related Field Programmable Gate Array product families - XC3000A,
XC3000L, XC3100A, XC3100L
• Ideal for a wide range of custom VLSI design tasks - Replaces TTL, MSI, and other PLD
logic - Integrates complete sub-systems into a single package - Avoids the NRE, time
delay, and risk of conventional masked gate arrays
• High-performance CMOS static memory technology - Guaranteed toggle rates of 70 to
370 MHz, logic delays from 7 to 1.5 ns - System clock speeds over 85 MHz - Low quiescent
and active power consumption
Flexible FPGA architecture - Compatible arrays ranging from 1,000 to 7,500 gate
complexity - Extensive register, combinatorial, and I/O capabilities - High fan-out signal
distribution, low-skew clock nets - Internal 3-state bus capabilities - TTL or CMOS input
thresholds - On-chip crystal oscillator amplifier

XC3000 series
• Unlimited reprogrammability - Easy design iteration - In-system logic changes
• Extensive packaging options - Over 20 different packages - Plastic and ceramic
surface-mount and pin-gridarray packages - Thin and Very Thin Quad Flat Pack (TQFP
and VQFP) options
• Ready for volume production - Standard, off-the-shelf product availability - 100%
factory pre-tested devices - Excellent reliability record
Complete Development System - Schematic capture, automatic place and route -
Logic and timing simulation - Interactive design editor for design optimization -
Timing calculator - Interfaces to popular design environments like Viewlogic,
Cadence, Mentor Graphics, and others

Configurable logic Blocks (CLB)
A configurable logic block (CLB) is the basic repeating logic resource on an FPGA. When
linked together by routing resources, the components in CLBs execute complex logic
functions, implement memory functions, and synchronize code on the FPGA.
CLBs contain smaller components, including flip-flops, look-up tables (LUTs), and
multiplexers
Flip-Flop—A circuit capable of two stable states that represents a single bit. A flip-flop is
the smallest storage resource on the FPGA. Each flip-flop in a CLB is a binary register
used to save logic states between clock cycles on an FPGA circuit.
Look-up Table (LUT)—A collection of gates hardwired on the FPGA. An LUT stores a
predefined list of outputs for every combination of inputs. LUTs provide a fast way to
retrieve the output of a logic operation because possible results are stored and then
referenced rather than calculated. The LUTs in a CLB can also implement FIFOs and
memory items in LabVIEW.
Multiplexer—A circuit that selects between two or more inputs and then returns the
selected input.

Configurable logic Blocks (CLB
Figure Configurable logic Blocks
To run on an FPGA target, LabVIEW implements much of the code using flip-flops,
LUTs, and multiplexers.

The input/output block (IOB) is used for communication between the problem
program and the system.
It provides the addresses of other control blocks, and maintains information about
the channel program, such as the type of chaining and the progress of I/O operations.
First define the IOB and specify its address as the only parameter of the EXCP or
EXCPVR macro instruction.
The input/output block (IOB) is not automatically constructed by a macro instruction;
it must be defined as a series of constants and be on a word boundary.
For unit-record and tape devices, the IOB is 32 bytes long.
For direct access, teleprocessing, and graphic devices, 8 additional bytes must be
provided. Use the system mapping macro IEZIOB, which expands into a DSECT, to
help in constructing an IOB.

Figure Input/Output Block (IOB) Format

IOBFLAG1 (1 byte)
Set bit positions 0, 1, 6, and 7. One-bits in positions 0 and 1 (IOBDATCH and
IOBCMDCH) indicate data chaining and command chaining, respectively. (If you specify
both data chaining and command chaining, the system does not use error recovery
routines except for the direct access and tape devices.) If an I/O error occurs while
your channel program executes, a failure to set the chaining bits in the IOB that
correspond to those in the CCW might make successful error recovery impossible. The
integrity of your data could be compromised.
A one-bit in position 6 (IOBUNREL) indicates that the channel program is not a related
request; that is, the channel program is not related to any other channel program. See
bits 2 and 3 of IOBFLAG2 below.
If you intend to issue an EXCP or XDAP macro with a BSAM, QSAM, or BPAM DCB, you
should turn on bit 7 (IOBSPSVC) to prevent access-method appendages from
processing the I/O request.

IOBFLAG2 (1 byte)
If you set bit 6 in the IOBFLAG1 field to zero, bits 2 and 3 (IOBRRT3 and IOBRRT2) in this
field must then be set to one of the following:
00, if any channel program or appendage associated with a related request might modify
this IOB or channel program.
01, if the conditions requiring a 00 setting do not apply, but the CHE or ABE appendage
might retry this channel program if it completes normally or with the unit-exception or
wrong-length-record bits on in the CSW.
10 in all other cases.
The combinations of bits 2 and 3 represent related requests,known as type 1 (00), type 2
(01), and type 3 (10). The type you use determines how much the system can overlap the
processing of related requests. Type 3 allows the greatest overlap, normally making it
possible to quickly reuse a device after a channel-end interruption. (Related requests that
were executed on a pre-MVS system are executed as type-1 requests if not modified.)

Field Programmable Gate Arrays (FPGA) are very interesting integrated circuits. The
possibility of completing different tasks by just reprogramming the FPGA made us think at
first view it was a kind of microcontroller. We were far from the reality. FPGAs are
reprogrammable logic/memory circuits and can be faster than any microcontroller. The
main difference is that a microcontroller has a program written in memory, and a FPGA
only has programmed connections/cells, so the data follows a continuous way through
programmed logic and memory cells, instead of being processed by only one ALU.
Programmable Interconnect Points are vital to any FPGA, they allow us to link the output
of a cell, or an input pad of the FPGA to any other cell/Pad in the circuit by making a
“path” for the data through the FPGA. Every way is fixed during the programming by
connecting metal lines with PIPs. These PIPs, well named, are programmable to permit us
to build any path we want.

Fig. Programmable Interconnect Point

HDL Programming
Digital circuits consist primarily of interconnected transistors. We design and analyze
these circuits with the aid of a hierarchical structure: we could, in theory, interpret a
central processing unit (CPU) as a vast sea of transistors, but it is much easier to organize
transistors into logic gates, logic gates into adders or registers or timing modules,
registers into memory banks, and so forth.
To describe digital circuits, textual language is used that is specifically intended to clearly
and concisely capture the defining features of digital design.
Such languages are called hardware description languages (HDLs).
The most popular hardware description languages are Verilog and VHDL. They are widely
used in conjunction with FPGAs, which are digital devices that are specifically designed to
facilitate the creation of customized digital circuits.
Hardware description languages allow you to describe a circuit using words and symbols,
and then development software can convert that textual description into configuration
data that is loaded into the FPGA in order to implement the desired functionality.
A hardware description language (HDL) is a programming language used to describe
the behavior or structure of digital circuits (ICs). HDLs are also used to stimulate the
circuit and check its response. Many HDLs are available, but VHDL and Verilog are by far
the most popular. Most CAD tools available in the market support these languages. VHDL
stands for “very high-speed integrated-circuit hardware description language.”

HDL Program for AND gate
entity Circuit_1 is
Port ( a : in STD_LOGIC;
b : in STD_LOGIC;
out1 : out STD_LOGIC);
end Circuit_1;
-----------------------------------------------------
architecture Behavioral of Circuit_1 is
begin
out1 <= ( a and b );
end Behavioral;

NOT gate and half adder HDL Programs
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY not1 IS
PORT( a : IN STD_LOGIC; b : OUT STD_LOGIC; );
END not1;
ARCHITECTURE behavioral OF not1 IS
BEGIN b <= NOT a;
END behavioral;
entity HALF_ADDER is
port (A, B: in BIT;
SUM, CARRY: out BIT);
end HALF_ADDER;

overview of Spartan 3E and Virtex II pro FPGA boards
The Spartan-3E family of Field-Programmable Gate Arrays (FPGAs) is specifically designed
to meet the needs of high volume, cost-sensitive consumer electronic applications.
The five-member family offers densities ranging from 100,000 to 1.6 million system gates.
The Spartan-3E family builds on the success of the earlier Spartan-3 family by increasing
the amount of logic per I/O, significantly reducing the cost per logic cell. New features
improve system performance and reduce the cost of configuration.
These Spartan-3E FPGA enhancements, combined with advanced 90 nm process
technology, deliver more functionality and bandwidth per dollar than was previously
possible, setting new standards in the programmable logic industry.
Because of their exceptionally low cost, Spartan-3E FPGAs are ideally suited to a wide
range of consumer electronics applications, including broadband access, home
networking, display/projection, and digital television equipment.
The Spartan-3E family is a superior alternative to mask programmed ASICs. FPGAs avoid
the high initial cost, the lengthy development cycles, and the inherent inflexibility of
conventional ASICs. Also, FPGA programmability permits design upgrades in the field with
no hardware replacement necessary, an impossibility with ASICs.

Features of Spartan 3E
Very low cost
high-performance logic solution for high-volume consumer-oriented applications
• Proven advanced 90-nanometer process technology
• Multi-voltage, multi-standard SelectIO™ interface pins
- Up to 376 I/O pins or 156 differential signal pairs
- LVCMOS, LVTTL, HSTL, and SSTL single-ended signal standards
- 3.3V, 2.5V, 1.8V, 1.5V, and 1.2V signaling
622+ Mb/s data transfer rate per I/O
- True LVDS, RSDS, mini-LVDS, differential HSTL/SSTL differential I/O
- Enhanced Double Data Rate (DDR) support
- DDR SDRAM support up to 333 Mb/s
Abundant, flexible logic resources
- Densities up to 33,192 logic cells, including optional shift register or distributed RAM
support
- Efficient wide multiplexers, wide logic
-Fast look-ahead carry logic
- - Enhanced 18 x 18 multipliers with optional pipeline
- - IEEE 1149.1/1532 JTAG programming/debug port

Hierarchical SelectRAM memory architecture
-Up to 648 Kbits of fast block RAM
- - Up to 231 Kbits of efficient distributed RAM
-Up to eight Digital Clock Managers (DCMs)
- - Clock skew elimination (delay locked loop)
-- Frequency synthesis, multiplication, division
-– High-resolution phase shifting
- - Wide frequency range (5 MHz to over 300 MHz)
-Eight global clocks plus eight additional clocks per each half of device, plus abundant
low-skew routing
- • Configuration interface to industry-standard PROMs
- - Low-cost, space
--saving SPI serial Flash PROM
-- x8 or x8/x16 parallel NOR Flash PROM
-Low-cost Xilinx Platform Flash with JTAG
-Fully compliant 32-/64-bit 33 MHz PCI support (66 MHz in some devices)
-• Low-cost QFP and BGA packaging options
- - Common footprints support easy density migration
-- Pb-free packaging options

Virtex II pro FPGA boards
The Virtex-II Pro (V2-Pro) development system can be used at virtually any level of the
engineering curricula, from introductory courses through advanced research projects.
Based on the Virtex-II Pro FPGA, the board can function as a digital design trainer, a
microprocessor development system, or a host for embedded processor cores and
complex digital systems.
It is powerful enough to support advanced research projects, but affordable enough to
be placed at every workstation. The expansion connectors can accommodate special-
purpose circuits and systems for years to come, so the board can remain at the core of an
engineering educational program indefinitely (see below for a current list of available
expansion boards)

Virtex-II Pro
Key Specifications
Logic Cells 30,816
BRAM 2,448Kb
DDR Up to 2GB of DDR SDRAM
Ethernet On-board 10/100 Ethernet PHY
Clocks 100MHz system clock, 75MHz SATA
Connectivity and On-board I/O
RS-232
RS-232 DB9 serial port
PS/2 Two PS-2 serial ports
Audio AC-97 audio CODEC with audio amplifier and speaker/headphone
output and line level output
Microphone
Microphone and line level audio input
Video
On-board XSGA output, up to 1200 x 1600 at 70Hz refresh

Virtex-II Pro
Switches 4
Push-buttons 5
LEDs 4 LEDs
User LED 4
User RGB LED 4
Electrical Power 4.5-5.5V
Logic Level 3.3V

DIGITALRESOURCES
 Lecture Notes – www.svec.edu.in
 Vidéo Lectures –

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microprocessor and microcontroller 8086 /8085

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