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Chapter 2:
Computer Systems
Computer Hardware
The physical pieces
of a computer
system, such as a
central processing
unit (CPU), a
microprocessor, a
printer, a disk drive,
or a modem
 Something you can
touch

Evolution of Computer Systems
 First
Generation - 1946-1959 - vacuum
tubes, rotating drum memory
 Second Generation - 1959-1964 transistors, magnetic core memory
 Third Generation - 1964-1979 integrated circuits, semiconductor
memory, operating systems
 Fourth Generation - 1979-present - LSI
and VLSI circuits, communications
Basic Components of Computers
 Input/Output
 Computer
Memory
 Arithmetic/Logical Unit
 Computer Files
 Control Unit
CPU
Control
Unit
Input
Arithmetic/ Logical
Unit
Memory
Files
Output
Stored Program Concept
 The
concept of preparing a precise list
of exactly what the computer is to do
(this list is called a program), loading or
storing this program in the memory of
the computer, and then letting the
control unit carry out the program at
electronic speed. The program must be
in a form that the control unit of the
computer has been built to understand.
Types of Computers
 Microcomputers
 Workstations
 Midrange
computers (minicomputers)
 Mainframes
 Supercomputers
 These categories are listed in general
order of increasing size, power, and
cost
Network Computer / NetPC
 Basic
idea of both is a stripped down,
less expensive PC for users who will
always be connected to a network
 Network Computer would have
minimal memory, processor, disk
storage (perhaps no hard drive)
 NetPC (Microsoft) would be more
powerful so that Windows could be
implemented locally
RISC Chips
 Reduced
Instruction Set Computing
 By working with a reduced instruction
set, designers were able to create a
smaller, faster chip than had been
possible previously
 Basis for HP 9000, IBM RISC/6000, Sun
SPARCsystem, other high-powered
workstations
Cache Memory
 Very
high speed, high cost storage unit
 Used as an intermediary between pieces
of the computer that operate at quite
different speeds
 Example -- between the control unit
(microprocessor) and main memory
 Example -- between disk drive and data
channel
Controller
A
hardware device to link input/output
or file devices to the CPU and memory
of large computer systems
 A highly specialized processor which
manages the operation of its attached
devices to free the CPU from these tasks
Data Channel
A
specialized input/output processor (a
computer) that takes over the function
of device communication from the CPU
 The role of the data channel is to correct
for the speed mismatch between the
slow peripheral devices and the very
fast CPU
Symmetric Multiprocessor
 Multiprocessor
machine in which all of
the processors (CPUs) are identical,
with each processor operating
independently of the others
 This design technique is used in most
mainframes and an increasing number
of midrange machines
Parallel Processor (PP)
A
multiprocessor configuration
(multiple CPUs installed as part of a
single computer system) designed to
give a separate piece of the same
program to each of the processors so
that work on the program can proceed
in parallel on the separate pieces
Massively Parallel Processor
(MPP)
A
parallel processing computer with
some large number of parallel
processors
 32 or more parallel CPUs if the different
CPUs are capable of performing
different instructions at the same time
 1000 or more parallel CPUs if the
different CPUs must all carry out the
same instruction at the same time
Changing Nature of Hardware
 Decreasing
price/performance ratio
-- faster and cheaper
 Increasing miniaturization
 Increasing multimedia (data, video,
sound)
 More plug-and-play and portability
 Greater management complexity due to
linking of distributed, cross-platform
technologies
The Information Technology
Industry
The Information
Technology industry
is the largest
industry in the
world, by far.
 Let’s look at the
primary players.

Top IS Companies in the World, 1996
1996 Rank
Company
Country
1996 IS Reve nue
1
IBM
U.S.
$75,947
2
Hewlett-Packard
U.S.
31,398
3
Fujitsu
Japan
29,717
4
Compaq Computer
U.S.
18,109
5
Hitachi
Japan
15,242
6
NEC
Japan
15,092
7
EDS
U.S.
14,441
8
Toshiba
Japan
14,050
9
Digital Equipment
U.S.
13,610
10
Microsoft
U.S.
9,435