computer organization & articture no. 4 from apcoms

8/14/2019 Computer Organization & Articture No. 4 from APCOMS

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The First Generation: Vacuum Tubes

ENIAC - background Electronic Numerical Integrator And Computer

Trajectory tables for weapons

Started 1943

Finished 1946 Too late for war effort

Used until 1955 A decimal not binary machine

Memory consists of 20 accumulators

each capable of holding 10 digits

A ring of 10 vacuum tubes representing each digit

At any one time only one vacuum tube was in ON state representingone of the ten digits

Hard to program by setting switches manually


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ENIAC - details

Decimal (not binary)

20 accumulators of 10 digits

Programmed manually by switches

18,000 vacuum tubes

30 tons

15,000 square feet

140 kW power consumption

5,000 additions per second


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Moores Law

Increased density of components

on chip Gordon Moore - cofounder of Intel Number of transistors on a chip will

double every year

Since 1970s development hasslowed a little

Number of transistors doublesevery 18 months

Cost of a chip has remainedalmost unchanged

Higher packing density meansshorter electrical paths, giving

higher performance Smaller size gives increased

flexibility

Reduced power and coolingrequirements

Fewer interconnections increases

reliability

Growth in CPU Transistor Count


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On the ENIAC, all programming was done at the digital logiclevel

Electronic, electrical engineers not by programmers

Programming the computer involved moving plugs and wires.

A different hardware configuration was needed to solve every

unique problem type Inventors of the ENIAC, conceived of a computer that could

store instructions in memory.

The invention of this idea by a mathematician, John von

Neumann Stored-program computers have become known as von NeumannArchitecture systems

The von Neumann Model

Configuring the ENIAC to solve a simple problem

required many days labor by skilled technicians.


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Todays version of stored-program computers have the followingcharacteristics: Three hardware systems:

A central processing unit (CPU) A main memory system An I/O system

The capacity to carry out sequential instruction processing. A single data path between the CPU and main memory.

This single path is known as the von Neumann bottleneck.
http://en.wikipedia.org/wiki/Image:Von_Neumann_architecture.svg


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This is a generaldepiction of a vonNeumann system: System passes all

I/O through ALU(accumulator)

Known as vonNeumannexecution cylce

These computers

employ a fetch-decode-executecycle to runprograms


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The von Neumann Model (fetch-decode-executecycle)

1. The control unit fetches the next instruction from memory

using the program counter to determine where the instructionis located.


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2. The instruction is decoded into a language that the ALU canunderstand.



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3. Any data operands required to execute the instruction arefetched from memory and placed into registers within theCPU.



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4. The ALU executes the instruction and places results inregisters or memory.



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Conventional stored-program computers have undergone many

incremental improvements over the years. These improvements include:

adding specialized buses, floating-point units, and cache memories,to name only a few.

But enormous improvements in computational power requiredeparture from the classic von Neumann architecture. Adding processors is one approach.

In the late 1960s,

high-performance computer systems were equipped with dualprocessors to increase computational throughput.

In the 1970s supercomputer systems were introduced with 32 processors

Supercomputers with 1,000 processors were built in the 1980s.

In 1999, IBM announced its Blue Gene system containing over 1million processors.

Non-von Neumann Models


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Parallel processing is only one method of providing increased

computational power.

More radical systems have reinvented the fundamental conceptsof computation.

These advanced systems include genetic computers, quantum

computers, and dataflow systems.

At this point, it is unclear whether any of these systems willprovide the basis for the next generation of computers.

Non-von Neumann Models


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von Neumann/Turing

Stored Program concept Main memory storing programs and data

ALU operating on binary data

Control unit interpreting instructions from memory andexecuting

Input and output equipment operated by control unit

With little exceptions all todays computer have samegeneral structure and function and refers to as von

Neumann machines Princeton Institute for Advanced Studies

IAS, Completed 1952


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IAS - details Set of registers (storage in CPU)

Memory Buffer Register

Contains a word to store in memory

Memory Address Register Address of memory to be read

Instruction Register Contains 8 bit opcode being executed

Instruction Buffer Register Holds instruction from memory

Program Counter Address of next instruction from

memory

Accumulator

Holds temporary operands and resultsof ALU operation

Multiplier Quotient E.g multiplication of two 40 bit number

gives 80 bit number Most significant 40 bits in AC

Least significant 40 bits in MQ


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Pentium Evolution

8080

first general purpose microprocessor 8 bit data path to memory

Used in first personal computer Altair

8086 much more powerful

16 bit machine

1 Mb addressable memory

instruction cache, prefetch few instructions

8088 (8 bit external bus) used in first IBM PC

80286 16 M byte memory addressable 80386

First 32 bit architecture machine

Support for multitasking


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Pentium Evolution

80486 sophisticated powerful cache and instruction pipelining

built in maths co-processor

Pentium

Superscalar Multiple instructions executed in parallel

Pentium Pro Increased superscalar organization

branch prediction data flow analysis

speculative execution


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Pentium Evolution (3)

Pentium II

MMX technology graphics, video & audio processing

Pentium III Additional floating point instructions for 3D graphics

Pentium 4 Note Arabic rather than Roman numerals

Further floating point and multimedia enhancements

Itanium 64 bit See Intel web pages for detailed information on

processors


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Generations of Computer

Vacuum tube - 1946-1957

Transistor - 1958-1964 Small scale integration - 1965 on

Up to 100 devices on a chip

Medium scale integration - to 1971 100-3,000 devices on a chip

Large scale integration - 1971-1977 3,000 - 100,000 devices on a chip

Very large scale integration - 1978 to date 100,000 - 100,000,000 devices on a chip

Ultra large scale integration Over 100,000,000 devices on a chip


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Moores Law (1965)

Gordon Moore, Intel founder

The density of transistors in an integrated circuit will

double every year. Contemporary version:

The density of silicon chips doubles every 18 months.

But this law cannot hold forever ...

Historical Development


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Rocks Law

Arthur Rock, Intel financier

The cost of capital equipment to build semiconductors

will double every four years. In 1968, a new chip plant cost about $12,000.

At the time, $12,000 would buy a nice home in

the suburbs.An executive earning $12,000 per year wasmaking a very comfortable living.



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Rocks Law

In 2005, a chip plants under construction cost over$2.5 billion.

For Moores Law to hold, Rocks Law must fall, or

vice versa. But no one can say which will give outfirst.

$2.5 billion is more than the gross domestic

product of some small countries, includingBelize, Bhutan, and the Republic of SierraLeone.



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Introduction

A computer system is made up from

Hardware is the physical medium, for example: circuit boards, processors or keyboard

Software is a computer program, for example: an operating system, an editor, a compiler

Firmware is a combination of software and hardware.Computer chips that have data or programs recorded onthem are firmware. These chips commonly include thefollowing:

ROMs (read-only memory)

PROMs (programmable read-only memory) EPROMs (erasable programmable read-only memory)

Firmware means microcode. Microcode is generic word for is a generic word for representing

certain functions in programming. These functions have special

status and special representation.


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Microprocessor

Microprocessor is an electronic circuit that functions as the

central processing unit (CPU) of a computer, providingcomputational control. Microprocessors are also used in other advanced electronic systems,

such as automobiles, and jet airliners.

Modern microprocessors incorporate transistors, in addition to othercomponents such as resistors, diodes, capacitors, and wires, allpacked into an area about the size of a postage stamp.

Microcontrollers Microcontrollers integrate all of the components (control, memory,

I/O) of a computer system into one integrated circuit. Microcontrollers are intended to be single chip solutions for systems

requiring low to moderate processing power.


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Microprocessor vs. Microcontroller

Microprocessor

CPU is stand-alone,RAM, ROM, I/O, timer areseparate

designer can decide on

the amount of ROM,RAM and I/O ports.

expansive

versatility

general-purpose

Microcontroller

CPU, RAM, ROM, I/O andtimer are all on a single chip

fix amount of on-chip ROM,RAM, I/O ports

for applications in which cost,power and space are critical

single-purpose


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Quiz # 1

Time 10 mins

Max 10 marks


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Quiz

In what ways are hardware and software different? In

what ways are they the same?

Calculate following a) How many milliseconds (ms) are in 1 second?

b) How many nanoseconds (ns) are in 1 millisecond? c) How many kilobytes are in 1 megabyte (MB)?

d How many megabytes are in 1 gigabyte (GB)?

e) How many bytes are in 20 megabytes?


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Answer to Q # 1

In what ways are hardware and software different? In

what ways are they the same?

Ans.

Between hardware and software, hardware provides

more speed, software provides more flexibility.Hardware and software are related through thePrinciple of Equivalence of Hardware and Software.They can solve problems equally, although solutions

are often easier in one versus the other.


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Answer to Q # 2

a) How many milliseconds (ms) are in 1 second?

b) How many nanoseconds (ns) are in 1 millisecond? c) How many kilobytes (KB) are in 1 gigabyte (GB)?

d) How many kilobytes are in 1 megabyte (MB)?

e How many megabytes are in 1 gigabyte (GB)?

f) How many bytes are in 20 megabytes? Ans. Typically, time is measured in powers of 10, so we

have: a. 1,000

b. 1,000,000 c. 1,000,000 (or 230/210=220)

d. 1,000 (or 220/210=210)

e. 1,000 (or 230/220=210)

f. 20,000,000 (or 20*220)

computer organization & articture no. 4 from apcoms

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