Unit 1 four part pocessor and memory

In this chapter you will learn about:
Internal structure of processor
Memory structure
Determining the speed of a processor
Different types of processors available
Determining the capacity of a memory
Different types of memory available
Several other terms related to the processor and main memory of a
computer system
Learning Objectives

Cache
Memory
Decode r Program
control register
Instruction register
Memory address
register
Memory buffer
register
Input/Output
register
General-
purpose register
Accumulato
r register
General-
purpose
register
General-
purpose
register
General-purpose
register
Control Unit Arithmetic Logic Unit
Central Processing Unit
I/ O
D E V
I C E
S
ROM PROM Flash
Main Memory (RAM)
Basic Processor & Memory Architecture
of a Computer System

Processor and Memory video
Processor and memory video

 The brain of a computer system
 Performs all major calculations and comparisons
 Activates and controls the operations of other units of a computer system
 Two basic components are
 Control Unit (CU)
 Arithmetic Logic Unit (ALU)
 No other single component of a computer
determines its overall performance as much as the CPU
Central Processing Unit (CPU)

 One of the two basic components of CPU
 Acts as the central nervous
system of a computer
system
 Selects and interprets program instructions,
and coordinates execution
 Has some special purpose registers and a decoder to
perform these activities
Control Unit (CU)

 One of the two basic components of CPU.
 Actual execution of instructions takes place in ALU
 Has some special purpose registers
 Has necessary circuitry to carry out all the arithmetic
and logic operations included in the CPU instruction
set
Arithmetic Logic Unit (ALU)

 CPU has built-in ability to execute a particular set of machine
instructions, called its instruction set
 Most CPUs have 200 or more instructions (such as add,
subtract, compare, etc.) in their instruction set
 CPUs made by different manufacturers have different
instruction sets
 Manufacturers tend to group their CPUs into “families” having
similar instruction sets
 New CPU whose instruction set includes instruction set of its
predecessor CPU is said to be backward compatible with its
predecessor
Instruction Set

 Special memory units, called registers, are used to hold
information on a temporary basis as the instructions are
interpreted and executed by the CPU
 Registers are part of the CPU (not main memory) of a
computer
 The length of a register, sometimes called its word size,
equals the number of bits it can store
 With all other parameters being the same, a CPU with
32-bit registers can process data twice larger than one
with 16-bit registers
Registers

Sr.
No.
Name of Register Function
1 Memory Address (MAR)
Holds address of the active memory
location
2 Memory Buffer (MBR)
Holds contents of the accessed
(read/written) memory word
3 Program Control (PC)
Holds address of the next instruction to be executed
4 Accumulator (A)
Holds data to be operated
upon, intermediate results, and the
results
5 Instruction (I)
Holds an instruction while it is
being executed
6 Input/Output (I/O)
Used to communicate with the
I/O devices
Functions of
Commonly Used
Registers

 Computer has a built-in system clock that emits millions of
regularly spaced electric pulses per second (known as clock
cycles)
 It takes one cycle to perform a basic operation, such as
moving a byte of data from one memory location to another
 Normally, several clock cycles are required to fetch, decode,
and execute a single program instruction
 Hence, shorter the clock cycle, faster the processor
 Clock speed (number of clock cycles per second) is measured
in Megahertz (106 cycles/sec) or Gigahertz (109 cycles/sec)
Processor Speed

Type of
Architecture
Features Usage
CISC (Complex
Instruction Set
Computer)
 Large instruction set
 Variable-length instructions
 Variety of addressing modes
 Complex & expensive to produce
Mostly used in
personal computers
RISC (Reduced
Instruction Set
Computer)
 Small instruction set
 Fixed-length instructions
 Reduced references to memory to
retrieve operands
Mostly used in
workstations
Types of Processor
(Continued on next slide)

Type of Architecture
Features Usage
EPIC (Explicitly Parallel
Instruction Computing)
 Allows software to communicate explicitly to the
processor when operations are parallel
 Uses tighter coupling between the compiler and the
processor
 Enables compiler to extract maximum parallelism in
the original code, and explicitly describe it to the
processor
Mostly used in high-end servers
and workstations
Types of Processor
(Continued from previous slide..)

Type of
Architecture
Features Usage
Multi-Core
Processor
 Processor chip has multiple
cooler-running, more energy-
efficient processing cores
 Improve overall performance
by handling more work in
parallel
 can share architectural
components, such as memory
elements and memory
management
Mostly used in
high-end servers
and workstations
Types of Processor

 Every computer has a temporary storage built into the
computer hardware
 It stores instructions and data of a program mainly
when the program is being executed by the CPU.
 This temporary storage is known as main memory,
primary storage, or simply memory.
 Physically, it consists of some chips either on the
motherboard or on a small circuit board attached to
the motherboard of a computer
 It has random access property.
 It is volatile.
Main Memory

Property Desirable
Primary
storage
Secondary
storage
Storage
capacity Large storage capacity Small Large
Access Time Fast access time Fast Slow
Cost per bit of
storage
Lower cost per bit High Low
Volatility Non-volatile Volatile Non-volatile
Access Random access
Random
access
Pseudo-
random
access or
sequential
access
Storage Evaluation Criteria

Addresses of
a memory
The words of a
memory
(total N words)
0
1
2
3
4
5
N-2
N-1
Bit 1 Bit 2
Main Memory Organization
Each word contains
the same number of
bits = word length

Main Memory Organization
Machines having smaller word-length are
slower in operation than machines having larger word-
length
A write to a memory location is destructive to its previous contents
A read from a memory location is non-destructive to its previous
contents

0501
0502
0503
Word
B O M B A Y
D E L H I
1024
Storage space is always allocated in
multiples of word-length
Faster in speed of calculation than
variable word-length memory
Normally used in large scientific
computers for gaining speed of
calculation
Fixed Word-length Memory
Address
Numbers

B
O
M
B
A
Y
0025
0026
0027
0028
0029
0030
0031
4096
D
E
L
H
I
0051
0052
0053
0054
0055
0056
4096
 Each memory location
can store only a single
character
 Slower in speed of
calculation than fixed
world-length memory
 Used in small business
computers for
optimizing the use of
storage space
Variable Word-length Memory
Note: With memory becoming cheaper and larger day-by-day, most modern
computers employ fixed-word-length memory organization
Address
Numbers
Address
Numbers

 Memory capacity of a computer is equal to the number of
bytes that can be stored in its primary storage
 Its units are:
Kilobytes (KB) : 1024 (210) bytes
Megabytes (MB) : 1,048,576 (220) bytes
Gigabytes (GB) : 1,073,741824 (230) bytes
Memory Capacity

 Primary storage of a computer is often referred to as RAM
because of its random access capability
 RAM chips are volatile memory
 A computer’s motherboard is designed in a manner that the
memory capacity can be enhanced by adding more memory
chips
 The additional RAM chips, which plug into special sockets on
the motherboard, are known as single-in-line memory
modules (SIMMs)
Random Access Memory (RAM) (video)

 ROM a non-volatile memory chip
 Data stored in a ROM can only be read and
used – they cannot be changed
 ROMs are mainly used to store programs
and data, which do not change and are
frequently used. For example, system boot
program
Read Only Memory (ROM)

Type Usage
Manufacturer-programmed
ROM
Data is burnt by the manufacturer of
the electronic equipment in which it
is used.
User-programmed ROM
or
Programmable ROM (PROM)
The user can load and store “read-
only” programs and data in it
Erasable PROM (EPROM)
The user can erase information
stored in it and the chip can be
reprogrammed to store new
information
Types of ROMs

Type Usage
Ultra Violet EPROM
(UVEPROM)
A type of EPROM chip in which the
stored information is erased by
exposing the chip for some time to
ultra-violet light
Electrically EPROM (EEPROM)
or
Flash memory
A type of EPROM chip in which the
stored information is erased by using
high voltage electric pulses
Types of ROMs

 It is commonly used for minimizing the memory-
processor speed mismatch.
 It is an extremely fast, small memory between CPU
and main memory whose access time is closer to the
processing speed of the CPU.
 It is used to temporarily store very active data and
instructions during processing.
Cache is pronounced as “cash”
Cache Memory

Questions
 Draw basic processor and memory Architecture of computer system.
 Write short note on
 Processor
 Main memory
 RAM
 ROM
 Cache Memory

Unit 1 four part pocessor and memory

More Related Content

What's hot (20)

Similar to Unit 1 four part pocessor and memory (20)

More from Neha Kurale (20)

Recently uploaded (20)

Unit 1 four part pocessor and memory