ece 456 computer architecture lecture #2 - architecture & organization instructor: dr. honggang...

ECE 456 Computer Architecture

Lecture #2 - Architecture & Organization

Instructor: Dr. Honggang Wang

Dr. Wang Lecture #2 2

Administrative Issues (9/18/13)• Project team set-up due Wednesday, Sept. 25

• If you missed the first class, go to the course website for syllabus and 1st lecture.

• My office hours:– M./W. 11 am -12pm, Fri. 12:00 -2:00 pm

www.faculty.umassd.edu/honggang.wang/teaching.html

Agenda

• Review Lecture #1

• Lecture #2



Review of Lecture #1In the first lecture, we covered the

• Course syllabus & operational details• Introduction to computer systems

– History of computers (a number of Firsts…...)– Evolution of Intel family – The evolution of computers has been characterized by

increasing processor speed/memory capacity/I/O capacity & speed and decreasing component size

– Performance balancing is a critical issue in computer system design


The First• The first general-purpose electronic digital

computer• The first computer to use the “Stored Program”

concept• The first computer bug • The first transistor• The first chip (integrated circuit)• The first minicomputer • The first microprocessor


The first general-purpose electronic digital computer

• ENIAC (Electronic Numerical Integrator And Computer)

• designed by Mauchly & Eckert at the U. Pennsylvania

• started 1943, finished 1946

• disassembled 1955

• 18,000 vacuum tubes

• 30 tons

• 30 feet × 50 feet

• 140 kw power consumption


The first computer to use the “Stored Program” concept

• IAS computer: named for the Institute for Advanced Study at Princeton University

• Began 1946, completed 1952

• The prototype of all subsequent general-purpose computers

• Structure

• Von Neumann machines


The first computer bug

• Grace Hopper found a moth stuck in a relay responsible for a malfunction

• An error in a computer program that prevents it from working correctly or produces an incorrect result

http://www.jamesshuggins.com/h/tek1/first_computer_bug.htm


The first transistor

• Invented at Bell labs in 1947

• Won a Nobel prize• Uses Silicon• Advantages

http://www.cedmagic.com/history/transistor-1947.htmlWilliam Shockley (seated at Brattain's laboratory bench), John Bardeen (left) and Walter Brattain (right)

http://en.wikipedia.org/wiki/Transistor


The first chip

• Invented by Jack Kilby at Texas Instruments in 1958

• Integrated Circuits are transistors, resistors, and capacitors integrated together into a single “chip”

• Won a Nobel prize


The first minicomputer - 1964

• DEC PDP-8 – Small enough to sit on a lab bench– Embedded applications– Flexible bus structure

Console controller

CPUMain

memoryI/O

moduleI/O

module...

Omnibus


The first microprocessor – 1971

• The Intel 4004 had 2,250 transistors

• four-bit

• 108Khz

• Called “Microchip”

The Pioneer 10 spacecraft used the 4004 microprocessor. It was launched on March 2, 1972 and was the first spacecraft and microprocessor to enter the Asteroid Belt.


Lecture #2 Topics

• Concept of computer architecture & computer

organization

• Contemporary computer architecture is

– von Neumann architecture, plus

– Interrupts


What is Computer Architecture?

• Term coined by IBM System/360 group in 1964

“The structure of a computer that a machine language programmer must understand to write a correct program for a machine”

– cited from Advanced Computer Architecture: A Design Space Approach, by D. Sima et al, Addison-Wesley 1997

– attributes visible to a programmer: registers, instruction set, instruction formats, addressing modes, etc

– example: “Is there a multiply instruction?”


What is Computer Organization? “The operational units and their interconnections

that realize the architectural specifications”

– about how features are implemented

– hardware details transparent to programmers: control signals, interfaces, memory technology

– example: “Will the multiply instruction be implemented by a hardware multiply unit or repeated addition?”


Architecture & Organization

• A particular architecture can span many years and encompass a number of different computer models (organizations)

– all Intel x86 family share the same basic architecture

– IBM System/370 family share the same basic architecture

– organization, thus price and performance differ between different models

– this gives code compatibility


Agenda

• Concept of computer architecture &

computer organization



– Interrupts


Von Neumann Architecture• General structure of von Neumann machines (the

IAS computer)


The IAS Computer(prototype of modern computers)

Chapter 2.1


Memory of IAS

• Memory: 1000 words /storage locations

– 40 binary bits per word– both data and instructions can be stored

– memory format for a number

– memory format for instructions Sign bit

0 1 39

Opcode Address Opcode Address0 398 20 28

Left instruction Right instruction


Instruction Set of IAS

• 21 instructions – data transfer between memory and registers or

between two registers

– unconditional branch

– conditional branch

– arithmetic

– address modify


Table 2.1The IAS Instruction Set


IAS Registers • Memory Buffer Register (MBR): contains a word to be

stored in memory or sent to I/O, or is used to receive a word from memory or I/O

• Accumulator (AC) & Multiplier Quotient (MQ): employed to hold temporarily operands and results of

ALU operations. • Memory Address Register (MAR): specifies the memory

address for the word to be written from or read into MBR.• Instruction Register (IR): contains the 8-bit opcode of the

instruction being executed• Instruction Buffer Register (IBR): employed to hold

temporarily the right-hand instruction from a word in memory

• Program Counter (PC): contains the address of the next instruction-pair to be fetched from memory


Instruction cycle

• Fetch– Opcode IR

– Address MAR

• Execute

Operation of IAS


Von Neumann Architecture – Key Characteristics

• Memory with addressable locations• Data and instructions are stored in a single

read-write memory• Basic sequential execution (unless explicitly

modified)


Administrative Issues (9/23/13, Monday.)

• Project Team– due Wednesday, Sep 25

• Homework #1– Assigned today, please go to the course website to download

problems

• Today’s topic– Finish Lecture #2 (Interrupt)


Agenda

• Concept of computer architecture &

computer organization



– interrupts


Interrupts

• All contemporary computers provide a mechanism by which other modules may interrupt the normal processing of the processor

• Contemporary computer architecture =

von Neumann architecture + interrupts

Chapter 3.2


Common Classes of Interrupts• Program interrupt

– division by zero, using undefined instructions, memory protection violations, arithmetic overflow

• Timer interrupt– generated by an internal processor timer

• I/O interrupt• Programmer-requested interrupt• Hardware failure

– power failure, hardware malfunctions


Why Interrupts? (1)

• Program flow of control without interrupts

• Code segments – 1,2,3: do not involve I/O

– 4: prepare for actual I/O operation

– Actual I/O command

– 5: complete I/O operation


• I/O devices are much slower than processor -- a very wasteful use of processor• At the point of each WRITE call, processor must pause and remain idle

Why Interrupts? (2)Why Interrupts? (2) -- Program Control flow & Timing: No Interrupts


Why Interrupts? (3)

• With interrupts, the processor can be engaged in executing other instructions while an I/O operation is in progress– improved processing efficiency

– concurrency


Illustration: Short I/O Wait

• Time required for the I/O operation is less than the time to complete the execution of instructions between write calls in the user program.


Why Interrupts? (4)Why Interrupts? (4) -- Program Control Flow & Timing with Interrupts: Short I/O Wait

concurrency

gain in efficiency


Illustration: Long I/O Wait

• Time required for the I/O operation is more than the time to complete the execution of instructions between write calls in the user program.


Why Interrupts? (5) -- Program Control Flow & Timing with Interrupts: Long I/O Wait

concurrency

gain in efficiency


Summary

• With the use of interrupts, concurrent execution of user program and I/O operation is made possible!

• Improved CPU processing efficiency!


Transfer of Control via Interrupts

Execution suspended with context saving

Execution resumedwith context recovery


Multiple Interrupts

• Various interrupt sources multiple interrupts

• How to deal with multiple interrupts?


How to deal with multiple interrupts?

• Can an interrupt be interrupted while it is being

processed?– NO: sequential interrupt processing

– YES: which interrupt should the CPU service?

priorities and nested interrupt processing


Sequential Interrupt Processing (1)• Disable interrupt (DI) while processing an interrupt, enable interrupt

(EI) before resuming the use program

DI

EI

EI


Sequential Interrupt Processing (2)

• Advantages: – simple: all interrupts are handled in strict sequential order

• Disadvantages– without considering relative priority or time-critical needs


Nested Interrupt Processing (1)


Nested Interrupt Processing (2): Example

• A system has three I/O devices– a printer with priority 2

– a disk with priority 4

– a communication line with priority 5

• Multiple interrupts (each takes 10 time units)time

0

printer interrupt

communication line interrupt

diskinterrupt

251510 20

Increasing priority


Time Sequence of Example Multiple Interruptstime

0

printer Interrupt (2)

comm. line Interrupt (5)

diskInterrupt (4)

251510 20

12

3

4

5

6


Nested Interrupt Processing (4)

• Advantages: – taking into account relative priority or time-critical needs

• Disadvantages– complex: defining priorities, saving information


Summary of Lecture #2

• Basic concept of computer architecture and

organization

• Von Neumann architecture (3 key concepts)

• Interrupts and multiple interrupts

• Contemporary computer architecture is von Neumann

architecture, plus interrupts


Things To Do• Find your partners for the class project

– email me the team information

• Check out the class website about– lecture notes

– reading assignments

– the project

Next Topics• Computer function & structure

ece 456 computer architecture lecture #2 - architecture & organization instructor: dr. honggang...

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