IS 139

Introduction

Overview - 1

How does a computer work? How components fit together Control signals, signaling methods, memory

types

How do I design a computer? Structure and behavior of computer systems ISA – instruction sets and formats, op codes,

data types, no. and type of registers, addressing modes, memory access methods, I/O mechanisms

Overview - 2

It’s all about function & structure

Structure => the way in which components are interrelated

Function => the operation of each individual component

Overview - 2

Architecture vs organization Architecture = attributes visible to

programmers e.g. instruction set, I/O mechanisms, addressing modes

Organization = units & their interconnections that realize architectural specs e.g. control signals, I/O interfaces, memory technology used

Manufacturers offer family of models => same architecture but different organizations

Why study computer architecture?

Program optimization – understanding why a program/algorithm runs slow

Understanding FP arithmetic crucial for large, real world systems

Design of peripheral systems i.e. device drivers

Design tradeoffs of embedded systems

Why study computer architecture?

Benchmarking

Building better compilers, OS’s

Writing software that takes advantage of hardware features - parallelism

You should be able to

Understand how programs written in high level languages get translated & executed by the H/W

Determine the performance of programs and what affects them

Understand techniques used by hardware designers to improve performance

Evaluate and compare the performance of different computing systems

General purpose computers

Software and hardware are interrelated

“Anything that can be done with software can also been done with hardware, and anything that can be done with hardware can be done with software” – Principal of Equivalence of H/W and S/W

This observation allows us to construct general purpose computing systems with simple instructions

Functions of general purpose computer

Data processing Data can take various forms

Data storage Temporarily or long term

Data movement Between itself & outside world

Control Orchestrates the different parts

Computer Organization & architecture - Stallings

What makes a computer?

Processor – data path & control

Memory

Mechanism to communicate with the outside world Input Output

Organization of a computer

Computer Organization & design - Patterson

Classes of computers

Desktop computers Familiar to most people Features: good performance, single user, execution of third party software

Servers Hidden from most users – accessible via a network – Cloud computing – in

data centers Features: handling large workloads, dependability, expandability From cheap low ends to extreme super computers with thousands of

processors used for forecasting, oil exploration

Embedded computers The largest class – wide range of applications & performance In cars, cell phones, video game consoles, planes Focus in limitation of power and cost

Growth of embedded computers in cell

phones

Tons of features

The essentials of Computer organization & architecture - Null

A look inside

The essentials of Computer organization & architecture - Null

How did we get here?

A lot has happened in the 60+ year life span E.g. if transportation industry developed at same

pace – here to London in 1 sec for a few cents

Different generations in the evolution of computers

Each generation defined by a distinct technology used to build a computer at that time

Why? – gives perspective & context into design decisions, understand why things are as they are

Generation 0: Mechanical Calculating Machines - 1

Defining characteristic - mechanical

1500s

There was a need to make decimal calculations faster

Mechanical calculator (Pascaline) – Blaise Pascal No memory, not programmable Used well into 20th century

Difference Engine – Charles Babbage “Father of Computing” Used method of difference to solve polynomial functions Was still a calculator

Generation 0: Mechanical Calculating Machines - 2

Analytical engine – an improvement over “Difference Engine” – It was a significant development More versatile – capable of performing any math

operation Similar to modern computers – mill (processor), store

(memory) & input/output devices Conditioning branch op – next instruction depending on

previous Ada, Countess of Lovelace suggested a plan for how the

machine should calculate numbers – The first programmer Used punch cards for input & programming – this method

survived for a long time

Generation 0

Drawbacks Slow – limited by the inertia of moving parts

(gears & pulleys) Cumbersome, unreliable & expensive

1st Generation: Vacuum Tube Computers (1945 -1953)

Defining characteristic: use of vacuum tubes as switching technology

Previous generations were mechanical but not electrical

Konrad Zuse – in 1930s added electrical tech & other improvements to Babbage’s design Z1 used electromechanical relays – was programmable,

had memory, arithmetic unit, control unit

Used discarded film for input

1st Generation

John Atanasoff, John Mauchly, J. Presper Eckert – credited with the invention of digital computers; However many others contributed

Their work resulted in ENIAC (Electronic numerical Integrator and Computer) in 1946 – the first all electronic, general purpose digital computer

Was built to facilitate weather prediction but ended up being financed & by the US army for ballistic trajection calculations

2nd Generation: Transistorized Computers (1954 – 1965)

Defining characteristic: Use of transistor as switching technology

Vacuum tube tech was not very dependable – they tended to burn out

In 1948 at Bell Laboratories – John Bardeen, Walter Brattain & William Shockley invented the TRANSISTOR

Was a revolution – Transistors are smaller, more reliable, consume less power

Caused circuitry to become more smaller & more reliable

Emergence of companies such as IBM, DEC & Unisys

3rd Generation: Integrated Circuit Computers (1965 –

1980)

Defining characteristic: Integration of dozens of transistors on a single silicon/germanium piece – “microchip” or “chip”

Kibly started with germanium, Robert Noyce eventually used silicon

Led to the silicon chip => “Silicon Valley”

Allowed dozens of transistors to exist on a single chip smaller than a single discrete transistor

Effect: Computers became faster, smaller & cheaper

E.g. IBM System/360, DEC’s PDP-8 and PDP-11

4th Generation: VLSI (1980 - )

Defining characteristic: Integration of very large numbers of transistors on a single chip

3rd generation had only multiple transistors on a chip

No. increased as manufacturing techniques improved: SSI (<100) => MSI (<1000) => LSI (<10,000) => VLSI (>10,000)

Led to the development of first microprocessor (4004) by Intel in 1971

Effect: allowed computers to be cheaper, smaller & faster – led to development of microprocessors

Computers for consumers: Altair 8800 => Apple I & II => IBM’s PC

5th Generation?

Quantum computing

Artificial Intelligence

Massively parallel machines

Non Von Neumann architectures

Common themes in evolution of computers

The same underlying fundamental concepts

Obsession with Increase in performance Decrease in size Decrease in cost

Moore’s Law

How small can we make transistors? How densely can we pack them

In 1965, Intel founder Gordon Moore stated “the density of transistors in an integrated circuit will double every year” – Moore’s Law

Ended up being every after every 18 months

Has hold up for almost 40 years

However cannot hold forever – physical & financial limits

Rock’s Law: “The cost of capital equipment to build semiconductors will double every for years”

Moore’s Law

Moore’s Law

Implications Cost of a chip remained almost unchanged

Cost of components decreased Higher packing density, shorter electrical paths

Higher speeds Smaller size

Increased flexibility Reduced power & cooling requirements Fewer interconnections

Increased reliability

Uniprocessor to Multiprocessor

Because of physical limits – power limits

Clock rates cannot increase forever Power = capacitive load x V^2 x frequency

Multiple processors per chip – “cores”

Programmers have to take advantage of multiple processors

Parallelism – similar to instruction level parallelism