Advanced Computer

Architectures

– HB49 –

Part 1

Vincenzo De Florio

K.U.Leuven / ESAT / ELECTA

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/2

Advanced Computer Architectures

• The domain of A.C.A. groups

technological and design solutions

that allow to provide, today,

a better answer

to the set of design goals

• Better = joint & improved

• Which design goals ?

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/3

Design framework

Application

driven

computer

architecture

design

Architecture-

conscious

application

(re-)design

Hardware

Instructionset

Micro-

program

Optim

izingcom

piler

Code

layer

Application

transform

systems

Reconfigur-

ability Low power

consumption

High

perfor-

mance

Dependability

Adapt-

ability

Mobility

compliancy

Real-

time

compli-

ancy

Bounded

complexity!

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/4

• Design goals of ACA include

• Performance • Power consumption

• Price • Size

• Dependability • Standard compliancy

• Safety • Scalability

• Real-timeliness • Security

• Application-

specific tailoring

• Embedding issues

Advanced Computer Architectures

• Scheduling

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/5

Advanced Computer

Architectures: aims & contents

• Introducing the basic concepts behind

ACA

• Discussing the path that has brought to

current technological and design

solutions

• Current computer design problems,

techniques, solutions

• Advanced solutions – domain specific,

parallelisms, trends…

• AI-specific ACA

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/6

Advanced Computer Architectures:

Goals of the course

• Give insight in the structure of modern

computer systems

• Understand current trends in the field of

computer design

• Teach how to consider the best match

between an (AI) problem and a computer

architecture

• Enable to use architectural knowledge to

optimise a service’s

Execution speed

Timeliness

Dependability

...

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/7

Course books

• Mandatory:

None.

• References:

Computer Architectures: A Quantitive Approach

(2nd edition)

David A. Patterson, John L. Hennessy

Morgan Kaufmann Publishers, 1996, ISBN 1-

55860-329-8

Third edition is available, though currently the

course focusses on 2nd

Advanced Computer Architectures: A design

space approach

Dezsö Sima, Terence Fountain, Péter Kacsuk,

Addison-Wesley, 1997, ISBN 0-201-42291-3

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/8

Powerpoint slides

Slides can be fetched from

http://www.esat.kuleuven.ac.be/~deflorio/aca

Slides are going to be updated

during the course

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/9

Exercises and laboratory sessions

• How to make use of a parallel

architecture...

• ...to reach a higher performance /

dependability / ...

• ...using C and a message passing

system...

• on a cluster of workstations.

• Under rethinking

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/10

Exam

• Oral with written preparation of 2 hours

approx.

• Closed book!

• Possible questions, e.g.

Given a specific AI problem and a set of design

goals, sketch a computer architecture that

matches them. Justify your choice.

Given a sketch of a computer architecture,

comment on the pros and cons of it from

different viewpoints (performance,

dependability, match with certain classes of AI

problems…)

Reply to some questions

Solve some exercises

See example on web page

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/11

Course contents

Basic Concepts

• Computer Design

• Computer Architectures for AI

• Computer Architectures in Practice

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/12

Basic Concepts

• Computer history

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/13

Basic Concepts

• Computer history

Generation -1: The early days (…-1642)

Generation 0: Mechanical (1642-1945)

Generation 1: Vacuum tubes (1945-1955)

Generation 2: Discrete transistors (1955-1965)

Generation 3: Integrated circuits (1965-1980)

Generation 4: VLSI (1980-?)

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/14

Basic Concepts

• Computer history

Generation -1: The early days (…-1642)

Generation 0: Mechanical (1642-1945)

Generation 1: Vacuum tubes (1945-1955)

Generation 2: Discrete transistors (1955-1965)

Generation 3: Integrated circuits (1965-1980)

Generation 4: VLSI (1980-?)

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/15

Generation -1: The early days

(…-1642)

• Calculation was a need since the early days for

transactions and maintaining inventories

• Early man counted by means of matching one set

of objects with another set (stones and sheep).

The operations of addition and subtraction were

simply the operations of adding or subtracting

groups of objects to the sack of counting stones

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/16

Generation -1: The early days

(…-1642)

= have the same cardinality

= same number of elements

= represent the same number!

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/17

Generation -1: The early days

(…-1642)

Call this manual procedure: “addition of integer numbers”

Representation

of number “2”

A

Representation

of number “1”

B

Procedure: put the contents of sack A into sack B

Result: sack B now contains …

Representation

of number “3”

B

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/18

Generation -1: The early days

(…-1642)

Key aspect:

• manipulating shells, one can

manipulate numbers…

• and perform simple computations

(additions, subtractions…)

• Very simple, error-prone computations

• Taking the time needed by objects

manipulation (quite slow)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/19

Generation -1: The early days

(…-1642)

• Early counting tables, named abaci, not only

formalized this counting method but also

introduced the concept of positional notation that

we use today.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/20

Generation -1: The early days

(…-1642)

111 –

010 =

101

• Only much later, counting became an abstract

process and numbers were represented by strings

of written characters called digits.

• New manual procedures could be applied on these

strings

• This allowed for computing on … papyrus.

• A little more complex computations

• Still manual, though a little faster to

execute

• Still error prone

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/21

Generation -1: The early days

(…-1642)

• In the twelfth century

Muhammad ibn Musa

Al'Khowarizmi

developed the concept

of a written process to

be followed to achieve

some goal, and

published this in a

book: hence the word

algorithm

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/22

Generation -1: The early days

(…-1642)

• For many years, “The” problem was:

• How to perform

A given algorithm

In a mechanical (non-manual) way,

Possibly faster than a man could do,

Possibly with less mistakes?

• For even more years computing just meant

“being able to perform arithmetical

operations”

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/23

Generation -1: The early days

(…-1642)

• Codex Madrid - Leonardo Da Vinci (1500)

Drawing of a mechanical calculator...

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/24

Basic Concepts

• Computer history

Generation -1: The early days (…-1642)

Generation 0: Mechanical (1642-1945)

Generation 1: Vacuum tubes (1945-1955)

Generation 2: Discrete transistors (1955-1965)

Generation 3: Integrated circuits (1965-1980)

Generation 4: VLSI (1980-?)

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/25

Generation 0: Mechanical

(1642-1945)

• Blaise Pascal, son of a tax collector, created in

1642 an adding machine with automatic carries

from one position to the next

• Addition was achieved by the underlying gears

turning as each digit was dialed in, the cumulative

total being displayed in a window above the

"keyboard”: mechanical, fixed (hardwired) algorithm

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/26

Generation 0: Mechanical

(1642-1945)

• An algorithm (actually, a single one!) was

computable

Mechanically (with minimal

intervention of the user)

Slightly faster than a man could do,

With less mistakes

• Computing “being able to perform

arithmetical operations”

• Numbers were represented onto

quadrants (positional notation)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/27

Generation 0: Mechanical

(1642-1945)

• Joseph-Marie Jacquard invented in 1801

an automatic loom using punched cards

for the control of the patterns in the

fabrics

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/28

Generation 0: Mechanical

(1642-1945)

• The machine performed according to a

fixed scheme

• The output was a function of a “program”

written onto punched cards

• Mechanical, faster, less mistakes

• Allowed to create very complex fabrics at

low cost

• Algorithms in software: First example of

a general purpose machine (for looming ;-)

• Unfortunately, Jacquard’s genial invention

was regarded as threatening jobs in the

cloth trade…

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/29

Generation 0: Mechanical

(1642-1945)

• Charles Babbage

recognized in 1822

that most navigation

tables contained lots

of errors leading to

the loss of ships.

• He applied to the

British Government

for assistance, and

received the first

government grant for

computer research

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/30

Generation 0: Mechanical

(1642-1945)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/31

Generation 0: Mechanical

(1642-1945)

• “I wish these calculations had been

executed by steam.”

• Babbage designs the Difference Engine to

compute, quickly and reliably, the entries

in navigation tables

• An application-specific hard-coded

machine

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/33

Generation 0: Mechanical

(1642-1945)

• Despite the grant from the British

government, Babbage never actually built

up its machine

• From 1832 he devoted all his energies and

all his money to a more ambitious

machine…

• Several years later, the Swedish Georg

Scheutz, on the basis of Babbage’s

publications, built a Difference Engine

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/34

Generation 0: Mechanical

(1642-1945)

• “The science of mathematics is becoming

too large in its parts to be fully dominated

by human intellect. The time is

approaching when its entire executable

part shall be appointed to the unfailing

power of mechanism.”

(Babbage’s letter to the king of Sweden, 1856)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/35

Generation 0: Mechanical

(1642-1945)

• Scheutz machine: completed in 1853

• Gold medal, Paris Exposition, 1855

• Sold to the Dudley Observatory in 1856

Not without consequences!

…director at Dudley got fired!

• Two sources:

• http://cdl.library.cornell.edu/cgi-

bin/moa/moa-cgi?notisid=ABS1821-

0002&byte=17574886

• Also available in

http://www.esat.kuleuven.ac.be/

~deflorio/aca/MaB*.gif

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/36

Generation 0: Mechanical

(1642-1945)

"The Swedish Calculating Machine [..] Our

readers will, of course, understand that the

machine is not self-acting. It does not give

logarithms, for example, merely for saying,

`Good machine, we want logarithms.’ It

must be fed both with manual power and

with calculation. The seed must be

according with the harvest wanted; men do

not grow figs or thistles, even in a

calculating machine. But the return is

greater than in most harvests; a very little

calculation makes the machine do an

enormous quantity of result by help of

barrel-organ exercise.”

“Calculating by Machinery”, The

Manufacturer and Builder, Vol. 2, No. 8, pp.

225-227, Aug. 1870.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/37

Generation 0: Mechanical

(1642-1945)

“This machine […] solves equations of 4th

and even

greater degree; operates in any numerical system

[…] The scientists, boosting their computation

capabilities as a miracle of natural law, will be soon

taken over by a simple machine that, under the

nearly blind guidance of a common man and by

means of custom movement, is going to dig the

infinite outer space with a security and depth way

greater than that of scientists.

Any man able to formulate a problem and having at

his disposal Mr. Scheutzs’ machine will have no need

for Archimedes’, Newtons, or Laplaces […] This

quasi-intelligent machine not only computes in a few

seconds what normally would require hours; it also

prints the obtained results, adding the advantages of

a neat calligraphy to those of computations with no

chance for errors.”

(Brisse, 1875, on the Scheutz machine)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/38

Generation 0: Mechanical

(1642-1945)

• Babbage’s new machine was the so-

called Analytical Engine

• This new machine is indeed the first

“computer” as we intend it today

• A programmable device whose structure

resembles the one of modern computers

• Despite he spent most of his money and

energies on the development of the new

machine, Babbage was not able to

succeed for the same reason, eg,

Leonardo could not actually realize many

of his designs: technology was not

enough mature yet

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/39

Generation 0: Mechanical

(1642-1945)

• Structure of the Analytical Engine

Input organs (to input data and code!)

Output organs

• The Store, where data and code are

stored

• The Mill (arithmetical unit), to execute

arithmetical operations

• The Control Unit, to impose a given

sequence to the operations

• Uses punched cards

• 1 addition in 3’’, 1 mul/div in 2’ to 4’

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/40

Generation 0: Mechanical

(1642-1945)

• A fully compliant A.E. was built in 1989-91 making

use of the original Babbage’s designs

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/41

Generation 0: Mechanical

(1642-1945)

• Ada Augusta King,

Countess of

Lovelace, may be

considered as “the

first programmer:”

She wrote the first

programs for

Babbage’s

Analytical Engine

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/43

Generation 0: Mechanical

(1642-1945)

• “The limits of arithmetic[al computations]

had been overcome the same moment the

[Jacquard’s] idea of using cards had come

to light, and the Analytical Machine has

actually nothing in common with the

“calculating machines”. Having allowed

machinery to mutually combine strings of

general symbols [opcodes] in series of

unlimited variety and length [the software

programs], a logic link [a homomorphism]

is established between material actions

and those abstract mental processes that

pertain to the most abstract branch of

mathematical sciences.”

Ada Lovelace, 1842

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/44

Interlude

• That is

No more simple arithmetical operations

No more single, predefined (set of)

computations

No more manual or semi-manual use

No more the human error rate

No more the human computing speed

“Strings of general symbols arranged into

series of unlimited variety and length.”

A noteworthy example: DNA

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/45

Generation 0: Mechanical

(1642-1945)

• “[…] So a new, vast and powerful

language has been developed […] such

that humanity will benefit from practical

applications becoming faster and more

precise than it was possible so far.

• To our knowledge, no machine like the

Analytical Engine exists or has ever been

imagined as a practical endeavor, the

same way nobody could ever imagine a

thinking machine.” (cited reference)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/46

Generation 0: Mechanical

(1642-1945)

• Analytical Engine Java Applet Simulator:

http://www.fourmilab.ch/babbage/applet.html

• Analytical Engine Command-line

Emulator:

http://www.fourmilab.ch/babbage/cmdline.html

• Excerpts from Babbage’s autobiography

http://www.fourmilab.ch/babbage/contents.html

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/47

Generation 0: Mechanical

(1642-1945)

• 1936: Alan M. Turing defines a model of

universal computability with his “Turing

Machine”

• A simple machine: complexity required to

compute any function is all in its software

• ‘‘The importance of the universal machine

is clear. We do not need to have an infinity

of different machines doing different jobs.

A single one will suffice. The engineering

problem of producing various machines for

various jobs is replaced by the office work

of programming the universal machine to

do these jobs.’’

(Turing, “Intelligent Machinery”)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/48

Generation 0: Mechanical

(1642-1945)

• The increasing population in the US, and the

demands of Congress to ask more questions in

each census, was making the processing of the

data a longer and longer process.

• It was anticipated that the 1890 census data

would not have been processed before the 1900

census was due – unless something was done to

improve the processing methodology.

• Herman Hollerith won the competition for the

delivery of data processing equipment to assist in

the processing of the data from the 1890 US

Census

• The company he founded, Hollerith Tabulating

Company, eventually became one of the three that

composed the Calculating-Tabulating-Recording

(C-T-R) company in 1914, eventually renamed as

IBM in 1924.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/49

Generation 0: Mechanical

(1642-1945)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/50

Generation 0: Mechanical

(1642-1945)

• Konrad Zuse, in Berlin, Germany, developed in

1935 his Z-1 computer in his parent's living room,

a relay computer, using binary arithmetic.

• Instruction cycle time: 6 seconds (0.17 Hz)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/51

Generation 0: Mechanical

(1642-1945)

• The first large scale, automatic, general purpose,

electromechanical calculator was the Harvard

Mark I (AKA IBM Automatic Sequence Control

Calculator [ASCC]) conceived by Howard Aiken in

the late 1930’s

• The ASCC was not a stored program machine but

instead was driven by a paper tape containing the

instructions.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/52

Generation 0: Mechanical

(1642-1945)

• Grace Murray Hopper found the first computer bug

beaten to death in the jaws of a relay. She glued it

into the logbook of the computer and thereafter

when the machine stopped (frequently) she told

Howard Aiken that they were "debugging" the

computer.

Lab book!!

Numbered pages

for USA patents

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/53

Basic Concepts

• Computer history

Generation -1: The early days (…-1642)

Generation 0: Mechanical (1642-1945)

Generation 1: Vacuum tubes (1945-1955)

Generation 2: Discrete transistors (1955-1965)

Generation 3: Integrated circuits (1965-1980)

Generation 4: VLSI (1980-?)

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/54

Generation 1: Vacuum tubes

(1945-1955)

• Work on ENIAC

was started in

1943 by John

Mauchly (left)

and J. Presper

Eckert

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/55

Generation 1: Vacuum tubes

• 18000 vacuum tubes, 1500 relays, 30 ton, 140 kW, 20 registers

of 10 decimal digits

• Programmed via 6000 multi-choice switches and tons of wires

• “In the future computers will weigh at most 1.5 ton”

(Popular Mechanics, 1949)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/56

Generation 1: Vacuum tubes

• A report on the ENIAC activity gives an

idea of how dependable computers were

in 1947:

• “Power line fluctuations and power

failures made continuous operation

directly off transformer mains an

impossibility […] down times were long;

error-free running periods were short […]

After many considerable improvements,

still trouble-free operating time remained

at about 100 hours a week during the last

6 years of the ENIAC's use.”

• I.e., an availability of about 60%!

Martin Weik, "The ENIAC Story", ORDNANCE –

The Journal of the American Ordnance

Association, Jan-Feb. 1961, available at URL

http://ftp.arl.mil/~mike/comphist/eniac-story.html

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/57

Generation 1: Vacuum tubes

• In 1946, John von Neumann realized the stored

program machine: the program was not anymore

stored in switches and wires or on punched paper,

but in program memory

• He designed a computer architecture consisting

of a controller, an ALU with accumulator and a

program/data memory, and used binary

arithmetics instead of decimal arithmetics

• Today’s computers still have this von Neumann

architecture (that actually derives from

Babbage’s, Zuse’s etc)

• He lay the foundation for the “von Neumann

bottleneck”, i.e. the bottleneck between the

memory and the rest of the computer; all newer

designs have been focussing on removing this

bottleneck

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/58

Generation 1: Vacuum tubes

• In 1948, the first stored program machine was

operational at the University of Manchester: the

Manchester Mark I http://www.computer50.org/mark1/MM1.html

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/59

Generation 1: Vacuum tubes

• In 1951, the Whirlwind computer was the first to

employ magnetic core memories, a principle that

is popping up recently again (MRAM), but then in

integrated form

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/60

Generation 1: Vacuum tubes

• A magnetic core, storing 256 bits

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/61

Interlude

• Yet another data representation

• Numbers are now represented in a

magnetic core

• How good are these representations w.r.t.

the “old ones”, e.g., on paper?

+ They are good for faster processing,

though…

- …can only be used to represent a small

(actually, finite!) set of numbers

- Rational numbers, such as

1/3 = 0.3333…. R-Q,

can be easily expressed on paper,

but cannot be captured by standard

computer data types!

1/3 [0.3…33, 0.3…34]

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/62

Interlude

- Due to physical properties of the

representation, magnetic contents may

be damaged or lost!

Each representation brings in some pros

and some cons.

An important design choice!

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/63

Generation 1: Vacuum tubes

• John von Neumann in 1952 with his new machine

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/64

Generation 1: Vacuum tubes

• Grace Hopper took up the concept of reusable

software in her 1952 paper entitled "The

Education of a Computer", (Proc. ACM Conference,

reprinted Annals of the History of Computing Vol.

9, No.3-4, pp. 271-281) in which she described the

techniques by which a computer could be used to

compile pre-written code segments to be

assembled into programs in correspondence with

codes written in a high level language -- thus

describing the concept of a compiler, and the

general concept of language translation.

• Similar to Turing’s “tables”

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/65

Generation 1: Vacuum tubes

• In 1954, John Backus of IBM developed a

programming language that allow(ed)|(s) users to

express their problems in commonly understood

mathematical formulae: FORTRAN

• The first FORTRAN compiler consisted of 2000

punched cards (2000 lines of – undocumented –

code)

• Still most scientific programs are written in

FORTRAN

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/66

Basic Concepts

• Computer history

Generation -1: The early days (…-1642)

Generation 0: Mechanical (1642-1945)

Generation 1: Vacuum tubes (1945-1955)

Generation 2: Discrete transistors (1955-1965)

Generation 3: Integrated circuits (1965-1980)

Generation 4: VLSI (1980-?)

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/67

Generation 2: Discrete transistors

(1955-1965)

• William Shockley, John Bardeen, and Walter

Brattain invent in 1947 the "transfer resistance"

device, later to be known as the transistor

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/68

Generation 2: Discrete transistors

(1955-1965)

• In 1955, IBM unveiled its IBM704, a mainframe

computer using discrete transistors, connected to

several dumb terminals

• The idea of central computer centers with

distributed data input and output was born

• First machine with floating point logic (5 kFlops,

clock: 300 kHz)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/69

Basic Concepts

• Computer history

Generation -1: The early days (…-1642)

Generation 0: Mechanical (1642-1945)

Generation 1: Vacuum tubes (1945-1955)

Generation 2: Discrete transistors (1955-1965)

Generation 3: Integrated circuits (1965-1980)

Generation 4: VLSI (1980-?)

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/70

Generation 3: Integrated circuits

(1965-1980)

• In 1958, Jack St. Clair Kilby of Texas Instruments

(Nobel prize physics, 2000) conceived and proved

his idea of integrating one transistor with

resistors and capacitors on a single

semiconductor chip (size: half paper clip), which

is a monolithic IC: a phase shift oscillator.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/71

Generation 3: Integrated circuits

(1965-1980)

• In 1961, Fernando Corbató, MIT, produced CTSS

(Compatible Time Sharing System) for the IBM

7090/94, the first effective time-sharing system

and hence the first real operating system

• In Great Britain the Atlas computer at the

University of Manchester became operational

(1962); it is the first machine to use virtual

memory and paging (see later on); its instruction

execution was pipelined (see later), and it

contained separate fixed- and floating-point

arithmetic units, capable of approximately 200

kFLOPS.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/72

Generation 3: Integrated circuits

(1965-1980)

• On April 7, 1964 IBM announced its System/360,

the first IBM family of compatible machines.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/73

Generation 3: Integrated circuits

(1965-1980)

• While some companies

were developing bigger

and faster machines,

Digital Equipment

Corporation introduced

the PDP-8 in 1965, the

first TRUE

minicomputer.

• The PDP-8 had a

minuscule instruction

set and a primitive

micro-language, and

excellent interface

capability. Thus the

PDP-8 became used

extensively as a

process control system

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/74

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/75

Basic Concepts

• Computer history

Generation -1: The early days (…-1642)

Generation 0: Mechanical (1642-1945)

Generation 1: Vacuum tubes (1945-1955)

Generation 2: Discrete transistors (1955-1965)

Generation 3: Integrated circuits (1965-1980)

Generation 4: VLSI (1980-?)

• Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/76

Generation 4: VLSI (1980-?)

• In 1971, Ted Hoff produced the Intel 4004 in

response to the request from a Japanese company

(Busicom) to create a chip for a calculator. It is

the first microprocessor, i.e. the first processor-

on-a-chip (2400 TOR)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/77

Generation 4: VLSI (1980-?)

• Developers Edward Roberts, William Yates and

Jim Bybee spent 1973-1974 to develop the MITS

Altair 8800, the first personal computer.

• Priced $375, it contained 256 bytes of memory,

had no keyboard, no display, and no auxiliary

storage device.

• Later, Bill Gates and Paul Allen wrote their first

product for the Altair – a BASIC compiler

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/78

Generation 4: VLSI (1980-?)

• IBM entered the field in 1981 with the IBM "PC”,

equipped with the DOS operating system,

developed under an agreement that gave

Microsoft all the profits in exchange for the

development costs having been borne by

Microsoft.

• Disregarding CP/M that had been the choice for

earlier machines, IBM chose to go in a radically

different direction, on the marketing assumption

(that turned out to be correct) that the purchasers

of the PC were a different breed than those who

were prepared to build their own system from a

kit.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/79

Generation 4: VLSI (1980-?)

• In 1984, Xerox PARC (Palo Alto Research Center)

presented the Alto, a desktop workstation with a

novel user interface: windows, icons, mouse

First mouse

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/80

Generation 4: VLSI (1980-?)

• In 1986, the Cray-XMP supercomputer with 4

processors reached a peak performance of 840

MFlops. It was water-cooled.

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/81

Generation 4: VLSI (1980-?)

• The same performance has been reached in a PC

by a single chip, the Pentium III, in Q1 2000

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/82

Summarizing: Computing Era:

A series of “revolutions”

19th

Century - 40ies: MECHANICAL

“I wish these calculations had been executed by

steam” (Babbage)

(40ies-50ies): New meaning for the word “computer”.

VACUUM TUBES. ENIAC, 30 tons.

“In the future computers will weigh at most 1.5

ton” (Popular Mechanics, 1949)

(50ies-60ies): Concept of compiler, high level

language, virtual machines. Fortran. MAINFRAMES.

Punched cards and primitive terminals

(60ies-70ies): OS, Virtual Memory, Pipelining.

MINICOMPUTERS. DEC PDP8. Terminal, keyboard,

display

(80ies): PERSONAL COMPUTING. XEROX Alto.

Windows, mice, icons. VLSI. The mC. RISC. OBJECT-

ORIENTATION

(90ies-current): The web. Global awareness (Y2K).

The “WIRELESS REVOLUTION”. Hand-held devices.

MOBILE PROGRAMS. Battery-awareness…

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/83

Interlude –

the key actors in the play

• Structure of the

Analytical Engine

Input organs (to input

data and code!)

Output organs

• The Store, where data

and code are stored

• The Mill (arithmetical

unit), to execute

arithmetical

operations

• The Control Unit, to

impose a given

sequence to the

operations

Data path

Controller

Control

signals

Status

signals

Data

inputs

Data

outputs

Control

inputs

Control

outputs

Program

memory

Address Instruction

• Structure of

microprocessors

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/84

Virtual machines

• Computer history

Virtual machines

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/85

The concept of virtual machines

• Reminder: basic structure of a

microprocessor

Data path

Controller

Control

signals

Status

signals

Data

inputs

Data

outputs

Control

inputs

Control

outputs

Program

memory

Address Instruction

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/86

The concept of virtual machines

• Operation:

The controller receives an instruction in binary

form from its program memory

For each instruction, it traverses a state

diagram where each transition is determined by

bits of the instruction and status signals from

the data path

In each state, the controller sends control

signals to the components of the data path

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/87

The concept of virtual machines

• How powerful do we choose an

instruction?

The richer the instruction, the more difficult the

controller becomes

The poorer the instruction, the more difficult

and tedious the art of programming becomes

We hence want a rich programming language at

the same time with having simple instructions

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/88

The concept of virtual machines

• Solution:

Multiple layers of virtual machines

• Example

Programmer writes in Java, which is

considered the machine language of a very rich

virtual machine (the Java Virtual Machine or

Java VM)

The Java VM knows how to deal with complex

DTs, recursion, functions, loops, …

This is translated in machine language for the

physical machine, which could be a RISC with

20 simple instructions

The translation process should try to use the

possibilities of the physical machine as good as

possible (e.g. single cycle multiple bit shift on a

barrel shifter, shift for a multiplication by a

power of 2, …)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/89

The concept of virtual machines

• Translation:

Compilation

Start with source code in high level language

Before execution of the application starts:

translate the source code to a lower level

language (i.e. the machine language of a poorer

virtual or physical machine)

Execute the lower level language

The source in the high level language is not

needed at execution time anymore

Interpretation

Start with source code in high level language

During execution of the application:

read one high level instruction

translate it into a sequence of lower level

instructions

execute the lower level instructions

The source is required during execution

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/90

The concept of virtual machines

• The translator itself consists of lower

level instructions

• Examples

Compilation

Pascal, C, Fortran, Cobol machine language

Java Java byte code

Interpretation

Basic machine language

Java byte code machine language

Perl, Python, PHP3 (scripting languages)

machine language

machine language micro-program instructions

(see next slide)

micro-program instructions state transitions

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/92

The concept of virtual machines

Digital logic: state transitions of next

state FSM Level 0

Micro-program Level 1

Conventional machine

(HEX code) Level 2

Assembly language

(mnemonics, variables, labels) Level 3

Intermediate machine independent

language (JAVA byte code) Level 4

Application specific language

(Java) Level 5

Interpretation

Interpretation

Interpretation

Compilation

Compilation (assembler)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/93

An example

• Ariel: a language to specify

Error recovery actions to be executed when

some events occur

Example:

when task 10 is found in error

restart task 10

wakeup task 11

• This is done outside the user application

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/94

An example

• Ariel: application specific language (deals

with error recovery)

• Error recovery = set of guarded actions

g : a1 … a

N ,

g’ : b1 … b

N’ ,

...

• Refer to nodes, tasks, groups of tasks

• Guards:

Faulty? Running? Rebooted? Isolated?

Transient?

• Actions:

Isolate! Start! Reboot! Enable! Send! ...

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/95

An example: Ariel: Basic ideas

DB User application Recovery

application

Error

Detection Store

Recovery starts

Query

Skip/execute

actions

Result

Recovery ends OK

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/96

An example: Ariel: Basic ideas

• Error recovery is coded in a special

language

Recovery language

• Recovery language is translated into an

intermediate, machine independent code

Recovery-code (r-code)

• Management of error recovery:

Run-time interpretation of the r-code

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/97

An example: an Ariel script

# .ariel

# specification of a strategy in the Ariel recovery language

# include files

# defines are importable from include files via #include statements

INCLUDE "my_definitions.h"

INCLUDE "../BACKBONE.H"

# definitions

# definitions start with the 'DEFINE' keyword, followed

# by an integer, an interval, or a list, followed

# by the equal sign and a role, that may be

# ASSISTANT(s) or MANAGER

NPROCS = 2

Define 1 = MANAGER

Define 2 = ASSISTANT

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/98

IF [ PHASE (T{VOTER1}) == {HAS_FAILED} AND PHASE (T2) == {OK} ]

THEN

STOP T{VOTER1}

SEND {WAKEUP} T{SPARE}

SEND {VOTER1} T{SPARE}

SEND {SPARE} T{VOTER2}

SEND {SPARE} T{VOTER3}

FI

IF [ KILLED N1 ] # if node 1 is down...

THEN

SEND 1000 T2 # send code "1000" to task 2

FI

IF [ KILLED N2 ] # if node 2 is down...

THEN

SEND 1000 T1 # send code "1000" to task 1

FI

An example: an Ariel script

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/99

bash-2.02$ art -s -i .ariel

Ariel translator, v2.0f 03-Mar-2000, (c) K.U.Leuven 1998, 1999, 2000.

Parsing file .ariel...

...done (158 lines in 0.030000 CPU secs, or 5266.667 lines per CPU

sec.)

Output written in file .rcode.

Press any key to finish processing...

An example: an Ariel script

Intermediate-level

language

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/100

An example of

intermediate language

Art translated Ariel strategy file: . . . .ariel

into rcode object file : . . . . . . . . . . . .rcode

line rcode opn1 opn2

-------------------------------------------------------------------

00000 SET_ROLE 1 Manager

00001 SET_ROLE 2 Assistant

00002 SET_DEFAULT_ACTION 666

00003 IF

00004 STORE_PHASE... Thread 0

00005 ...COMPARE == 9999

00006 STORE_PHASE... Thread 2

00007 ...COMPARE == 1

00008 AND

00009 FALSE 10

00010 KILL Thread @line(4)

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/101

An example of

intermediate language

line rcode opn1 opn2

-------------------------------------------------------------------

. . . . . . . . . . . .

00029 IF

00030 PUSH... 0

00031 ...KILLED Node 2

00032 FALSE 3

00033 PUSH... 1000

00034 ...SEND Thread 1

00035 FI

00036 ANEW_OA_OBJECTS 1

00037 STOP

R-code

translation of

…

IF [ KILLED N2 ] # if node 2 is down...

THEN

SEND 1000 T1 # send code "1000" to task T1

FI

…this

Ariel

fragment

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/102

Ariel and r-code: global view

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/103

The concept of virtual machines

• Decisions to be taken during computer

design

Richness of the digital logic

How large is the transistor budget

How much of the budget do we spend on the

controller as opposed to the data path and the

on-chip memories (typically 10%)

Distance between two consecutive virtual

machines

Large distance makes it difficult for a translator

to employ all features offered by the lower level

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/104

The concept of virtual machines

• History of virtual machines

before 1950: 2 levels:

digital logic

conventional machine

1950: 3 levels:

digital logic

micro-program

conventional machine

1952: 4 levels

digital logic

micro-program

conventional machine

assembly language

© V. De Florio

KULeuven 2002

Basic

Concepts

Computer

Design

Computer

Architectures

In Practice

Computer

Architectures

For AI

1/105

The concept of virtual machines

• History of virtual machines

1955: 5 levels

digital logic

micro-program

conventional machine

assembly language

application specific language

1965 ?: 6 levels

digital logic

micro-program

conventional machine

assembly language

intermediate machine independent language

application specific language