1.1. HISTORICAL BACKGROUND

In this section, we would like to provide a historical background on the evolution of

cornerstone ideas in the computing industry. We should emphasize at the outset that

the effort to build computers has not originated at one single place. There is every

reason for us to believe that attempts to build the first computer existed in different

geographically distributed places. We also firmly believe that building a computer

requires teamwork. Therefore, when some people attribute a machine to the name

of a single researcher, what they actually mean is that such researcher may have

led the team who introduced the machine. We, therefore, see it more appropriate

to mention the machine and the place it was first introduced without linking that

to a specific name. We believe that such an approach is fair and should eliminate

any controversy about researchers and their names.

It is probably fair to say that the first program-controlled (mechanical) computer

ever build was the Z1 (1938). This was followed in 1939 by the Z2 as the first oper-

ational program-controlled computer with fixed-point arithmetic. However, the first

recorded university-based attempt to build a computer originated on Iowa State

University campus in the early 1940s. Researchers on that campus were able to

build a small-scale special-purpose electronic computer. However, that computer

was never completely operational. Just about the same time a complete design of

a fully functional programmable special-purpose machine, the Z3, was reported in

Germany in 1941. It appears that the lack of funding prevented such design from

being implemented. History recorded that while these two attempts were in progress,

researchers from different parts of the world had opportunities to gain first-hand

experience through their visits to the laboratories and institutes carrying out the

work. It is assumed that such first-hand visits and interchange of ideas enabled

the visitors to embark on similar projects in their own laboratories back home.

As far as general-purpose machines are concerned, the University of Pennsylvania

is recorded to have hosted the building of the Electronic Numerical Integrator and

Calculator (ENIAC) machine in 1944. It was the first operational general-purpose

machine built using vacuum tubes. The machine was primarily built to help compute

artillery firing tables during World War II. It was programmable through manual set-

ting of switches and plugging of cables. The machine was slow by today’s standard,

with a limited amount of storage and primitive programmability. An improved version

of the ENIAC was proposed on the same campus. The improved version of the

ENIAC, called the Electronic Discrete Variable Automatic Computer (EDVAC),

was an attempt to improve the way programs are entered and explore the concept

of stored programs. It was not until 1952 that the EDVAC project was completed.

Inspired by the ideas implemented in the ENIAC, researchers at the Institute for

Advanced Study (IAS) at Princeton built (in 1946) the IAS machine, which was

about 10 times faster than the ENIAC.

1.1. HISTORICAL BACKGROUND

3

In 1946 and while the EDVAC project was in progress, a similar project was

initiated at Cambridge University. The project was to build a stored-program com-

puter, known as the Electronic Delay Storage Automatic Calculator (EDSAC). It

was in 1949 that the EDSAC became the world’s first full-scale, stored-program,

fully operational computer. A spin-off of the EDSAC resulted in a series of machines

introduced at Harvard. The series consisted of MARK I, II, III, and IV. The latter

two machines introduced the concept of separate memories for instructions and

data. The term Harvard Architecture was given to such machines to indicate the

use of separate memories. It should be noted that the term Harvard Architecture

is used today to describe machines with separate cache for instructions and data.

The first general-purpose commercial computer, the UNIVersal Automatic

Computer (UNIVAC I), was on the market by the middle of 1951. It represented an

improvement over the BINAC, which was built in 1949. IBM announced its first com-

puter, the IBM701, in 1952. The early 1950s witnessed a slowdown in the computer

industry. In 1964 IBM announced a line of products under the name IBM 360 series.

The series included a number of models that varied in price and performance. This led

Digital Equipment Corporation (DEC) to introduce the first minicomputer, the PDP-8.

It was considered a remarkably low-cost machine. Intel introduced the first micropro-

cessor, the Intel 4004, in 1971. The world witnessed the birth of the first personal

computer (PC) in 1977 when Apple computer series were first introduced. In 1977

the world also witnessed the introduction of the VAX-11/780 by DEC. Intel followed

suit by introducing the first of the most popular microprocessor, the 80 Â 86 series.

Personal computers, which were introduced in 1977 by Altair, Processor

Technology, North Star, Tandy, Commodore, Apple, and many others, enhanced

the productivity of end-users in numerous departments. Personal computers from

Compaq, Apple, IBM, Dell, and many others, soon became pervasive, and changed

the face of computing.

In parallel with small-scale machines, supercomputers were coming into play.

The first such supercomputer, the CDC 6600, was introduced in 1961 by Control

Data Corporation. Cray Research Corporation introduced the best cost/performance

supercomputer, the Cray-1, in 1976.

The 1980s and 1990s witnessed the introduction of many commercial parallel

computers with multiple processors. They can generally be classified into two

main categories: (1) shared memory and (2) distributed memory systems. The

number of processors in a single machine ranged from several in a shared

memory computer to hundreds of thousands in a massively parallel system.

Examples of parallel computers during this era include Sequent Symmetry, Intel

iPSC, nCUBE, Intel Paragon, Thinking Machines (CM-2, CM-5), MsPar (MP),

Fujitsu (VPP500), and others.

One of the clear trends in computing is the substitution of centralized servers by

networks of computers. These networks connect inexpensive, powerful desktop

machines to form unequaled computing power. Local area networks (LAN) of

powerful personal computers and workstations began to replace mainframes and

minis by 1990. These individual desktop computers were soon to be connected

into larger complexes of computing by wide area networks (WAN).

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INTRODUCTION TO COMPUTER SYSTEMS

TABLE 1.1

Four Decades of Computing

Feature Batch Time-sharing Desktop Network

Decade 1960s 1970s 1980s 1990s

Location Computer room Terminal room Desktop Mobile

Users Experts Specialists Individuals Groups

Data Alphanumeric Text, numbers Fonts, graphs Multimedia

Objective Calculate Access Present Communicate

Interface Punched card Keyboard & CRT See & point Ask & tell

Operation Process Edit Layout Orchestrate

Connectivity None Peripheral cable LAN Internet

Owners Corporate computer Divisional IS shops Departmental Everyone

centers end-users

CRT, cathode ray tube; LAN, local area network.

The pervasiveness of the Internet created interest in network computing and more

recently in grid computing. Grids are geographically distributed platforms of com-

putation. They should provide dependable, consistent, pervasive, and inexpensive

access to high-end computational facilities.

Table 1.1 is modified from a table proposed by Lawrence Tesler (1995). In this

table, major characteristics of the different computing paradigms are associated with

each decade of computing, starting from 1960.