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Computer Architecture
                      EE222 (A)
                                Summer 2010


Pre-requisite: Logic Design (EE221)




                            EE-222 Computer Architecture
                                Muhammad Bilal Saif        1
Books
• Text Book
  – Computer System Architecture (3rd edition), by
    Morris Mano

• Reference Books :
  – Computer System Design and Architecture (2nd
    Edition), V. P. Heuring, and H.F. Jordan
  – Computer Architecture and Organization (3rd
    edition) by John P. Hayes

                  EE-222 Computer Architecture
                      Muhammad Bilal Saif            2
Course Objective
• To learn the
  – basics of computer components
     •   Registers
     •   ALU
     •   DMA
     •   Memory types
     •   etc.
  – Operation of components of computer
• During the course we shall not be considering any
  specific design but we shall be considering
  general design, which is mostly true for all
  designs.
                        EE-222 Computer Architecture
                            Muhammad Bilal Saif        3
Course Contents
• This course shall cover the following main topics
   –    microcomputer
   –   microprocessor register
   –   ALU design
   –   control unit design
   –   instruction cycle
   –   memory types
   –   Read/Write cycles
   –   memory mapping
   –   address decoding
   –   address decoder design
   –   Interrupts
   –   Polling
   –   I/O devices interfacing
   –   DMA
   –   bus arbitration
   –   introduction to CISC/RISC architecture


                                 EE-222 Computer Architecture
                                     Muhammad Bilal Saif        4
Course Grading
•   Class Quizzes (9% surprise + 21% announced) 30%
•   Assignments                                 5%
•   Class participation                         5%
•   Mid term exam                              25%
•   Final Comprehensive Exam                   35%




                     EE-222 Computer Architecture
                         Muhammad Bilal Saif          5
Quizzes
• There shall be seven announced quizzes
  during the semester.
• Quizzes shall not be rescheduled for any body
  in any case.




                 EE-222 Computer Architecture
                     Muhammad Bilal Saif          6
Quizzes schedule
                  Quiz No.                         Week and Date
                     1                                Week – 02
                                             17th June 2010 (Thursday)
                     2                                Week – 03
                                            23rd June 2010 (Wednesday)
                     3                                Week – 04
                                            30th June 2010 (Wednesday)
                     4                                Week – 05
                                             7th July 2010 (Wednesday)
                     5                                Week – 06
                                            14th July 2010 (Wednesday)
                     6                                Week – 07
                                            21st July 2010 (Wednesday)
                     7                                Week – 08
                                            28th July 2010 (Wednesday)

Time:    7:00 pm (In case of change, new time shall be announced)
Venue:   MLH               EE-222 Computer Architecture
                             Muhammad Bilal Saif                         7
website
• Course website
  – http://192.168.1.32


• From website you can
  – Get lectures
  – Check your attendances (Most probably
    attendance shall not be displayed on notice
    board)

                   EE-222 Computer Architecture
                       Muhammad Bilal Saif        8
Computer Architecture


  ?                                  ?



      EE-222 Computer Architecture
          Muhammad Bilal Saif            9
Computer
    • The term computer is in use from mid 17th
      century, literally meaning “one who
      computes” (one is usually person performing
      mathematical calculations) [1]

    • Now-a-day:
      A computer is a machine that manipulates
      data according to a set of instructions.

[1] http://en.wikipedia.org/wiki/Human_computer
                                    EE-222 Computer Architecture
                                        Muhammad Bilal Saif        10
Computer
• Tell that whether the following devices are
  computer or not.
  –   AND, OR gate IC
  –   Digital clock
  –   ATM machine
  –   Calculator
  –   Abacus
  –   Register IC
  –   Keyboard
  –   Mouse
                        EE-222 Computer Architecture
                            Muhammad Bilal Saif        11
Computer
• Presently most widely accepted definition of computer
  is
• “A device that computes, especially a programmable
  electronic machine that performs high-speed
  mathematical or logical operations or that assembles,
  stores, correlates, or otherwise processes information.”
                                                        (Answer.com)
• According to the above definition, computer should
  have the following parts.
      1.   Processor
      2.   Input output devices
      3.   Memory
      4.   Storage (optional)

                         EE-222 Computer Architecture
                             Muhammad Bilal Saif                  12
Architecture
    • What is architecture??
    • Why should be we aware of the computer
      architecture????????

Computer architecture should be known to increase the yield (instruction/sec) of
the computer




                             EE-222 Computer Architecture
                                 Muhammad Bilal Saif                      13
Chapter – 04
REGISTER TRANSFER AND
   MICROOPERATION



     EE-222 Computer Architecture
         Muhammad Bilal Saif        14
Chapter 4
Register Transfer and Microoperations
•   4-1   Register Transfer Language
•   4-2   Register Transfer
•   4-3   Bus and Memory Transfer
•   4-4   Arithmetic Microoperations
•   4-5   Logic Microoperations
•   4-6   Shift Microoperations
•   4-7   Arithmetic Logic Shift Units

                    EE-222 Computer Architecture
                        Muhammad Bilal Saif        15
Register Transfer Language (RTL)
• Combinational and sequential circuits (learned in logic
  design) can be used to create simple digital systems.
• These are too basic to design a digital computer.

• To overcome this problem digital systems are
  frequently characterized in terms of
   – the registers they contain, and
   – the operations that can be performed on registers data.

• RTL: a language for describing the behavior of
  computer in terms of step-wise register contents.

                      EE-222 Computer Architecture
                          Muhammad Bilal Saif                  16
Microoperations
    • The operations executed on the data stored in
      registers are called microoperations.
    • Operands can be in one or more registers.
    • The functions built into registers are examples of
      microoperations
         – Shift
         – Load
         – Clear
         – Increment
         – …
e.g. a bidirectional shift register is capable of performing the shift right and shift
left microoperations             EE-222 Computer Architecture
                                   Muhammad Bilal Saif                           17
An elementary operation performed (during
 one clock pulse), on the information stored
 in one or more registers

       b
       a
      sel_a                                            1 clock cycle
                 Registers              ALU
      sel_b
      sel_c        (R)                   (f)

       c

Rd  f(R1, R2)     or        Rd  f(R1)           or      Rd  f(Rd)

      f: shift, load, clear, increment, add, subtract, complement,
             and, or, xor, …
                   EE-222 Computer Architecture
                       Muhammad Bilal Saif                             18
ORGANIZATION OF A DIGITAL SYSTEM
• Internal hardware organization of digital
  computer can be best explained by

  – Set of registers and their functions
  – Set of allowable microoperations provided by the
    organization of the computer
  – Control signals that properly perform the
    microoperations

                  EE-222 Computer Architecture
                      Muhammad Bilal Saif              19
Register Transfer Language (RTL)
• Rather than specifying a digital system in words, a
  specific notation is used, register transfer language
• For any function of the computer, the register
  transfer language can be used to describe the
  (sequence of) microoperations
• Register transfer language
   – A symbolic language
   – A convenient tool for describing the internal organization of digital
     computers
   – Can also be used to facilitate the design process of digital systems.

                           EE-222 Computer Architecture
                               Muhammad Bilal Saif                           20
Hardware required for microoperation

    • The term “Register transfer” implies the
      availability of hardware logic circuit that can
      perform a stated microoperation and transfer
      the result of operation to the same or another
      register.
                                    R1  R1 + R 2

Above statement of RTL specifies that system has circuit to perform addition
and then saving the result in R1


                             EE-222 Computer Architecture
                                 Muhammad Bilal Saif                      21
Chapter 4
Register Transfer and Microoperations
•   4-1   Register Transfer Language
•   4-2   Register Transfer
•   4-3   Bus and Memory Transfer
•   4-4   Arithmetic Microoperations
•   4-5   Logic Microoperations
•   4-6   Shift Microoperations
•   4-7   Arithmetic Logic Shift Units

                    EE-222 Computer Architecture
                        Muhammad Bilal Saif        22
Register Designation
• Registers are designated by capital letters, sometimes followed by
  numbers (e.g., A, R13, IR)
• Often the names indicate function:
    – MAR           - memory address register
    – PC            - program counter
    – IR            - instruction register

• Registers and their contents can be viewed and represented in various
  ways
    – A register can be viewed as a single entity:

                                          MAR

    – Registers may also be represented showing the bits of data they contain

                                 7 6 5 4 3 2 1 0

                                 EE-222 Computer Architecture
                                     Muhammad Bilal Saif                        23
Register Designation
• Designation of a register
          - a register
          - a bit of a register
          - portion of a register



• Common ways of drawing the block diagram of a register

         Register                                            Showing individual bits
                         R1                                       7   6   5   4     3   2   1   0
          15                                    0            15               8 7               0
                             R2                                       PC(H)             PC(L)

         Numbering of bits                                   Subfields




                                  EE-222 Computer Architecture
                                      Muhammad Bilal Saif                                           24
REGISTER TRANSFER
• Copying the contents of one register to another is a register
  transfer
• A register transfer is indicated as
                            R2  R1
   – In this case the contents of register R1 are copied
     (loaded) into register R2
   – A simultaneous transfer of all bits from the source R1
     to the destination register R2, during one clock pulse
   – Note that this is a non-destructive; i.e. the contents of
     R1 are not altered by copying (loading) them to R2
                       EE-222 Computer Architecture
                           Muhammad Bilal Saif                    25
CONTROL FUNCTIONS
    • Often actions need to only occur if a certain condition is true
    • This is similar to an “if” statement in a programming language
    • In digital systems, this is often done via a control signal, called a
      control function
        – If the signal is 1, the action takes place, otherwise
          not
    • This is represented as:
                             P: R2  R1
        Which means “if P = 1, then load the contents of
         register R1 into register R2”, i.e., if (P = 1) then
         (R2  R1)
P can be considered as control signal generated in the control section.
                                EE-222 Computer Architecture
                                    Muhammad Bilal Saif                       26
HARDWARE IMPLEMENTATION OF
     CONTROLLED TRANSFERS
Implementation of controlled transfer
     P: R2 R1


Block diagram                    Control       P   Load
                                                                R2       Clock
                                 Circuit                             n
                                                   Load
                                           0                    R1


Timing diagram
                                               t          t+1

                  Clock

                  Load
                          Transfer occurs here


                          Registers and control circuit are positive-edge-triggered
                          EE-222 Computer Architecture
                              Muhammad Bilal Saif                                27
Example
• Write such a RTL statement which shows that
  the transfer from register Y to register Z shall
  only occur when A and B are both low.
• Also draw the block diagram of the RTL
  statement found in the above part.
• Write another RTL statement which shows
  that the transfer from register Y to register Z
  shall occur only when either A or B is one; nor
  when both are zero or one.
                  EE-222 Computer Architecture
                      Muhammad Bilal Saif        28
SIMULTANEOUS OPERATIONS
   • If two or more operations are to occur
     simultaneously, they are separated with commas


                        P: R3  R5,, MAR  IR

   • Here, if the control function P = 1, load the contents
     of R5 into R3, and at the same time (clock), load the
     contents of register IR into register MAR
For above stated simultaneous operation, two buses are required

                            EE-222 Computer Architecture
                                Muhammad Bilal Saif               29
SIMULTANEOUS OPERATIONS (Contd.)
• Consider the following simultaneous
  operation
              T: R2R1, R1  R2

• For such operations; in addition to two buses,
  registers with edge triggered flip-flops are also
  required.


                  EE-222 Computer Architecture
                      Muhammad Bilal Saif         30
Practice
    • Tell how many buses are required in the
      following examples and whether edge
      triggered phenomenon is essential or not
    1. P: R1  R2
    2. T: R1  R2, R3  R2
    3. S: R1  R5, R2  R4
    4. R: R1  R2, R3  R1
Edge triggering becomes essential, if a register is source and destination at the
same time
                              EE-222 Computer Architecture
                                  Muhammad Bilal Saif                       31
BASIC SYMBOLS FOR REGISTER
               TRANSFERS
       Symbols           Description                     Examples
Capital letters &   Denotes a register             MAR, R2
   numerals

Parentheses ()      Denotes a part of a            R2(0-7), R2(L)
                    register
                    Denotes transfer of            R2  R1
Arrow 
                    information

Colon :             Denotes termination of P:
                    control function
Comma ,             Separates two micro-           A  B, B  A
                    operations

                    EE-222 Computer Architecture
                        Muhammad Bilal Saif                         32

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Lecture 1

  • 1. Computer Architecture EE222 (A) Summer 2010 Pre-requisite: Logic Design (EE221) EE-222 Computer Architecture Muhammad Bilal Saif 1
  • 2. Books • Text Book – Computer System Architecture (3rd edition), by Morris Mano • Reference Books : – Computer System Design and Architecture (2nd Edition), V. P. Heuring, and H.F. Jordan – Computer Architecture and Organization (3rd edition) by John P. Hayes EE-222 Computer Architecture Muhammad Bilal Saif 2
  • 3. Course Objective • To learn the – basics of computer components • Registers • ALU • DMA • Memory types • etc. – Operation of components of computer • During the course we shall not be considering any specific design but we shall be considering general design, which is mostly true for all designs. EE-222 Computer Architecture Muhammad Bilal Saif 3
  • 4. Course Contents • This course shall cover the following main topics – microcomputer – microprocessor register – ALU design – control unit design – instruction cycle – memory types – Read/Write cycles – memory mapping – address decoding – address decoder design – Interrupts – Polling – I/O devices interfacing – DMA – bus arbitration – introduction to CISC/RISC architecture EE-222 Computer Architecture Muhammad Bilal Saif 4
  • 5. Course Grading • Class Quizzes (9% surprise + 21% announced) 30% • Assignments 5% • Class participation 5% • Mid term exam 25% • Final Comprehensive Exam 35% EE-222 Computer Architecture Muhammad Bilal Saif 5
  • 6. Quizzes • There shall be seven announced quizzes during the semester. • Quizzes shall not be rescheduled for any body in any case. EE-222 Computer Architecture Muhammad Bilal Saif 6
  • 7. Quizzes schedule Quiz No. Week and Date 1 Week – 02 17th June 2010 (Thursday) 2 Week – 03 23rd June 2010 (Wednesday) 3 Week – 04 30th June 2010 (Wednesday) 4 Week – 05 7th July 2010 (Wednesday) 5 Week – 06 14th July 2010 (Wednesday) 6 Week – 07 21st July 2010 (Wednesday) 7 Week – 08 28th July 2010 (Wednesday) Time: 7:00 pm (In case of change, new time shall be announced) Venue: MLH EE-222 Computer Architecture Muhammad Bilal Saif 7
  • 8. website • Course website – http://192.168.1.32 • From website you can – Get lectures – Check your attendances (Most probably attendance shall not be displayed on notice board) EE-222 Computer Architecture Muhammad Bilal Saif 8
  • 9. Computer Architecture ? ? EE-222 Computer Architecture Muhammad Bilal Saif 9
  • 10. Computer • The term computer is in use from mid 17th century, literally meaning “one who computes” (one is usually person performing mathematical calculations) [1] • Now-a-day: A computer is a machine that manipulates data according to a set of instructions. [1] http://en.wikipedia.org/wiki/Human_computer EE-222 Computer Architecture Muhammad Bilal Saif 10
  • 11. Computer • Tell that whether the following devices are computer or not. – AND, OR gate IC – Digital clock – ATM machine – Calculator – Abacus – Register IC – Keyboard – Mouse EE-222 Computer Architecture Muhammad Bilal Saif 11
  • 12. Computer • Presently most widely accepted definition of computer is • “A device that computes, especially a programmable electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information.” (Answer.com) • According to the above definition, computer should have the following parts. 1. Processor 2. Input output devices 3. Memory 4. Storage (optional) EE-222 Computer Architecture Muhammad Bilal Saif 12
  • 13. Architecture • What is architecture?? • Why should be we aware of the computer architecture???????? Computer architecture should be known to increase the yield (instruction/sec) of the computer EE-222 Computer Architecture Muhammad Bilal Saif 13
  • 14. Chapter – 04 REGISTER TRANSFER AND MICROOPERATION EE-222 Computer Architecture Muhammad Bilal Saif 14
  • 15. Chapter 4 Register Transfer and Microoperations • 4-1 Register Transfer Language • 4-2 Register Transfer • 4-3 Bus and Memory Transfer • 4-4 Arithmetic Microoperations • 4-5 Logic Microoperations • 4-6 Shift Microoperations • 4-7 Arithmetic Logic Shift Units EE-222 Computer Architecture Muhammad Bilal Saif 15
  • 16. Register Transfer Language (RTL) • Combinational and sequential circuits (learned in logic design) can be used to create simple digital systems. • These are too basic to design a digital computer. • To overcome this problem digital systems are frequently characterized in terms of – the registers they contain, and – the operations that can be performed on registers data. • RTL: a language for describing the behavior of computer in terms of step-wise register contents. EE-222 Computer Architecture Muhammad Bilal Saif 16
  • 17. Microoperations • The operations executed on the data stored in registers are called microoperations. • Operands can be in one or more registers. • The functions built into registers are examples of microoperations – Shift – Load – Clear – Increment – … e.g. a bidirectional shift register is capable of performing the shift right and shift left microoperations EE-222 Computer Architecture Muhammad Bilal Saif 17
  • 18. An elementary operation performed (during one clock pulse), on the information stored in one or more registers b a sel_a 1 clock cycle Registers ALU sel_b sel_c (R) (f) c Rd  f(R1, R2) or Rd  f(R1) or Rd  f(Rd) f: shift, load, clear, increment, add, subtract, complement, and, or, xor, … EE-222 Computer Architecture Muhammad Bilal Saif 18
  • 19. ORGANIZATION OF A DIGITAL SYSTEM • Internal hardware organization of digital computer can be best explained by – Set of registers and their functions – Set of allowable microoperations provided by the organization of the computer – Control signals that properly perform the microoperations EE-222 Computer Architecture Muhammad Bilal Saif 19
  • 20. Register Transfer Language (RTL) • Rather than specifying a digital system in words, a specific notation is used, register transfer language • For any function of the computer, the register transfer language can be used to describe the (sequence of) microoperations • Register transfer language – A symbolic language – A convenient tool for describing the internal organization of digital computers – Can also be used to facilitate the design process of digital systems. EE-222 Computer Architecture Muhammad Bilal Saif 20
  • 21. Hardware required for microoperation • The term “Register transfer” implies the availability of hardware logic circuit that can perform a stated microoperation and transfer the result of operation to the same or another register. R1  R1 + R 2 Above statement of RTL specifies that system has circuit to perform addition and then saving the result in R1 EE-222 Computer Architecture Muhammad Bilal Saif 21
  • 22. Chapter 4 Register Transfer and Microoperations • 4-1 Register Transfer Language • 4-2 Register Transfer • 4-3 Bus and Memory Transfer • 4-4 Arithmetic Microoperations • 4-5 Logic Microoperations • 4-6 Shift Microoperations • 4-7 Arithmetic Logic Shift Units EE-222 Computer Architecture Muhammad Bilal Saif 22
  • 23. Register Designation • Registers are designated by capital letters, sometimes followed by numbers (e.g., A, R13, IR) • Often the names indicate function: – MAR - memory address register – PC - program counter – IR - instruction register • Registers and their contents can be viewed and represented in various ways – A register can be viewed as a single entity: MAR – Registers may also be represented showing the bits of data they contain 7 6 5 4 3 2 1 0 EE-222 Computer Architecture Muhammad Bilal Saif 23
  • 24. Register Designation • Designation of a register - a register - a bit of a register - portion of a register • Common ways of drawing the block diagram of a register Register Showing individual bits R1 7 6 5 4 3 2 1 0 15 0 15 8 7 0 R2 PC(H) PC(L) Numbering of bits Subfields EE-222 Computer Architecture Muhammad Bilal Saif 24
  • 25. REGISTER TRANSFER • Copying the contents of one register to another is a register transfer • A register transfer is indicated as R2  R1 – In this case the contents of register R1 are copied (loaded) into register R2 – A simultaneous transfer of all bits from the source R1 to the destination register R2, during one clock pulse – Note that this is a non-destructive; i.e. the contents of R1 are not altered by copying (loading) them to R2 EE-222 Computer Architecture Muhammad Bilal Saif 25
  • 26. CONTROL FUNCTIONS • Often actions need to only occur if a certain condition is true • This is similar to an “if” statement in a programming language • In digital systems, this is often done via a control signal, called a control function – If the signal is 1, the action takes place, otherwise not • This is represented as: P: R2  R1 Which means “if P = 1, then load the contents of register R1 into register R2”, i.e., if (P = 1) then (R2  R1) P can be considered as control signal generated in the control section. EE-222 Computer Architecture Muhammad Bilal Saif 26
  • 27. HARDWARE IMPLEMENTATION OF CONTROLLED TRANSFERS Implementation of controlled transfer P: R2 R1 Block diagram Control P Load R2 Clock Circuit n Load 0 R1 Timing diagram t t+1 Clock Load Transfer occurs here Registers and control circuit are positive-edge-triggered EE-222 Computer Architecture Muhammad Bilal Saif 27
  • 28. Example • Write such a RTL statement which shows that the transfer from register Y to register Z shall only occur when A and B are both low. • Also draw the block diagram of the RTL statement found in the above part. • Write another RTL statement which shows that the transfer from register Y to register Z shall occur only when either A or B is one; nor when both are zero or one. EE-222 Computer Architecture Muhammad Bilal Saif 28
  • 29. SIMULTANEOUS OPERATIONS • If two or more operations are to occur simultaneously, they are separated with commas P: R3  R5,, MAR  IR • Here, if the control function P = 1, load the contents of R5 into R3, and at the same time (clock), load the contents of register IR into register MAR For above stated simultaneous operation, two buses are required EE-222 Computer Architecture Muhammad Bilal Saif 29
  • 30. SIMULTANEOUS OPERATIONS (Contd.) • Consider the following simultaneous operation T: R2R1, R1  R2 • For such operations; in addition to two buses, registers with edge triggered flip-flops are also required. EE-222 Computer Architecture Muhammad Bilal Saif 30
  • 31. Practice • Tell how many buses are required in the following examples and whether edge triggered phenomenon is essential or not 1. P: R1  R2 2. T: R1  R2, R3  R2 3. S: R1  R5, R2  R4 4. R: R1  R2, R3  R1 Edge triggering becomes essential, if a register is source and destination at the same time EE-222 Computer Architecture Muhammad Bilal Saif 31
  • 32. BASIC SYMBOLS FOR REGISTER TRANSFERS Symbols Description Examples Capital letters & Denotes a register MAR, R2 numerals Parentheses () Denotes a part of a R2(0-7), R2(L) register Denotes transfer of R2  R1 Arrow  information Colon : Denotes termination of P: control function Comma , Separates two micro- A  B, B  A operations EE-222 Computer Architecture Muhammad Bilal Saif 32