The document provides an overview and introduction to computer and network technology. It discusses the history of computers from the abacus to modern machines. It covers the basic hardware components of a computer including the CPU, memory, input/output devices, and how they work together. It also examines the basic software components including operating systems, programming languages, utilities, and applications. Finally, it outlines the different types of computers and their uses as well as how computers can be connected in various configurations.

1. Computer & Network Technology
Chamila Fernando
BSc(Eng) Hons,MBA,MIEEE

2. Lecture 1: Introduction
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Overview
History of Computers
Application Areas
Types of Computers
Computer Configurations
Computers as Information Processors
Lecture 1: Introduction
2

3. Lecture 1: Introduction
 Basic Machine Hardware Architecture
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CPU
Memory/Storage
Main Memory
Input/Output Devices
 Basic Machine Software
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Flowcharts
Languages
Operating Systems
System Utilities
Applications
 What’s in Computer & Network Technology..?
Lecture 1: Introduction
3

4. Overview of Part 1
 Number system: how is information
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

represented in a computer.
Boolean Algebra: the basis for logic design and
manipulation of information.
Logic gates: what are the gates used, and how
circuits can be made from gates.
Function simplification: to reduce the size of
design, increase speed, etc.
Lecture 1: Introduction
4

5. Overview of Part 1
 Combinational circuits: simple circuit design
without memory.
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Sequential circuits: circuit design with memory.
Disk: storage techniques.
Bus: internal communication.
I/O: devices, technology, etc.
Lecture 1: Introduction
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6. History of Computers
 Abacus invented in Babylonia in 3000BC
 Adding machine by Blaise Pascal (1642)
 Difference engine and the analytical engine by Charles
Babbage (1842)
 IBM first electromechanical computer (using relays)
designed by Howard Aiken (1937) was based on
punched cards.
 used to calculate tables of mathematical functions
Lecture 1: Introduction
6

7. History of Computers
 1st Generation Computers (1940s to early 1950s) – based
on vacuum tubes technology.
 1943 – ENIAC: first fully electronic computer, designed by John
Mauchly
 1944 – Mark I: Howard Aiken
 1946 – EDVAC: first stored program computers, designed by John
von Neumann
 2nd Generation Computers (late 50s to early 60s) – based
on transistors technology.
 more reliable, less expensive, low heat dissipation
 IBM 7000 series, DEC PDP-1
Lecture 1: Introduction
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8. History of Computers
 3rd Generation Computers (late 60s to early 80s) –
integrated circuits (IC).
 IBM 360 series, DEC PDP-8
 IC – many transistors packed into single container
 low prices, high packing density
 4th Generation Computers (present day) LSI/VLSI
 small size, low-cost, large memory, ultra-fast PCs to
supercomputers
 5th Generation Computers (future)
 massively parallel, large knowledge bases, intelligent
 Japan, Europe and US advanced research programs
Lecture 1: Introduction
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9. History of Computers
 Web sites
 History of Computers
(http://www.comp.nus.edu.sg/~sf100/c1f7.htm)
 ACM Timeline of Computing History
(http://www.computer.org/computer/timeline)
 The Virtual Museum of Computing
(http://www.comlab.ox.ac.uk/archive/other/museums/computin
g.html)
 IEEE Annals of the History of Computing
(http://www.computer.org/annals/)
 and others (surf the web)
Lecture 1: Introduction
9

10. Application Areas
 Scientific: weather forecasting, simulation, spaceprogram.
 one of the earliest application areas.
 heavy computation but small amount of data.
 Commercial: accounting, banking, inventory, sales.
 changes nature of business – information is money.
 high data throughput, simple calculations.
 Manufacturing: numerical control, CAD/CAM, integration.
 graphics, interfacing, device-drivers, networks.
Lecture 1: Introduction
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11. Application Areas
 Real-time & Control System: air-traffic control,
aircraft,nuclear power station.
 real time, very fast, safety-critical.
 Educational & Recreational
 CAI software, multi-media, games, Internet, World Wide Web.
 Telecommunication
 Network, SCV, Singapore One.
Lecture 1: Introduction
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12. Types of Computers
 Supercomputers:
 very fast (Gflops) but expensive machine($10m), vector or parallel
processors, used in scientific applications and simulations.
 Mainframes:
 fast (>10mips) but expensive ($1m), high-throughput, used in
large commercial organisations, support many concurrent users
interactively.
 Mini-computers:
 fast but affordable ($200k), used in medium-sized organisations
(e.g. SoC), support multiple users.
Lecture 1: Introduction
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13. Types of Computers
 Workstations:
 affordable ($20k) and fast single-user systems (20 riscs mips),
good graphics capabilities, engineering, network-based
computing.
 Micro/Personal/Home Computers:
 cheap and affordable ($3k), transportable, home use, good for
games and as educational tool, word processing, suitable for
small enterprise.
Lecture 1: Introduction
13

14. Computer Configurations
 Stand-alone computer system
 Modem connection
Lecture 1: Introduction
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15. Computer Configurations
 Terminals-host connections
Lecture 1: Introduction
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16. Computer Configurations
 Network of computers
Lecture 1: Introduction
16

17. Computers as Information Processors
Driver
Example: An automobile
augments our power of
locomotion.
A computer is a device
capable of solving problems
according to designed
program. It simply augments
our power of storage and
speed of calculation.
Lecture 1: Introduction
Programmer
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18. Computers as Information Processors
 Unlike previous inventions, computers are special because
they are general-purpose.
general-purpose
 Could be used to perform a variety of tasks.
 Computer = Hardware + Software.
Software
 Hardware: physical components for computation/processing;
should be simple, fast, reliable.
 Software: set of instructions to perform tasks to specifications;
should be flexible, user-friendly, sophisticated.
Lecture 1: Introduction
18

19. Computer as Information Processors
Computer are Information Processors
Raw
data
Computer
system
Processed
information
Data Units:
1 bit (binary digit): one of two values (0 or 1)
1 byte: 8-bits
1 word: 1, 2, or 4 bytes, or more (depends on ALU)
Lecture 1: Introduction
19

20. Basic Machine Hardware Architecture
 Main Components:
 CPU (Central Processing Unit: controls devices and processes
data).
 Memory: stores programs and intermediate data.
Memory
 Input Devices: accept data from outside world.
Devices
 Output Devices: presents data to the outside world.
Devices
 An analogy with Human Information Processors:
 CPU – brain’s reasoning powers
 Memory – brain’s memory
 Input Devices – eyes, ears, sensory sub-system
 Output Devices – mouth, hands, facial and body expressions
Lecture 1: Introduction
20

21. Basic Machine Hardware Architecture
Headphone
(Output)
Monitor
(Output)
Hardware box
(contains
processor, memory,
buses etc.)
Mouse and Keyboard (Input)
Lecture 1: Introduction
21

22. Basic Machine Hardware Architecture
Network card and
CRT card
Motherboard
(Printed Circuit
Board)
Floppy disk
drive and
Hard disk
drive
Cage for
mounting drives
Slots for RAM chips
Processor
© above picture: Patterson and Hennessy
Lecture 1: Introduction
22

23. Hardware – CPU
 CPU = control unit + ALU + registers
 Control Unit : monitors and directs sequences of
instructions
 Execution Cycle (repeated):
 fetch (next instruction)
 decode
 execute
Lecture 1: Introduction
23

24. Hardware – CPU
 ALU: performs simple arithmetic and logical operations.
 Examples: Add, subtract, and, or, invert, increment etc.
A
select
B
R = A op B
ALU
n-bits operations
R
Lecture 1: Introduction
24

25. Hardware – CPU
 Registers: temporary results + status information
 ACC (accumulator) – current data
 PC (program counter) – points to next instruction
 IR (instruction register) – current instruction
 MA (memory address) – address to read/write
 MB (memory buffer) – data to read/write
Lecture 1: Introduction
25

26. Hardware – Memory/Storage
 Purpose: to store program and data.
 Desirable Traits: fast access, large capacity, economical,
non-volatile.
 However, most memory devices do not have all these
traits.
Lecture 1: Introduction
26

27. Hardware – Memory/Storage
 Solution: hierarchical combination
Fast, expensive
(small numbers),
volatile
registers
main memory
disk storage
magnetic tapes
Lecture 1: Introduction
Slow, cheap
(large numbers),
non-volatile
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28. Hardware – Main Memory
 Fast BUT volatile (need power to maintain data)
 Logical structure – table of memory cells/units.
addresses
M
A
R
M
B
R
address
8 bits or more
0
1
2
3
memory
cells
data
2m-3
2m-2
2m-1
Lecture 1: Introduction
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29. Hardware – Main Memory
 Memory cells may be grouped into pages (say 512
consecutive words per page).
 Units
 1 KBytes = 1024 (or 210) bytes
 1 MBytes = 1024 Kbytes (or 220 bytes)
 1 GBytes = 1024 Mbytes (or 230 bytes)
Lecture 1: Introduction
29

30. Hardware – Input/Output Devices
 Input devices: read/accept data (into computer)
devices
 obsolete: card reader, paper tape reader
 present: keyboard, mouse, light-pen, optical char reader
 future: voice and vision recognition.
 Output devices: write/display data (to users)
devices
 obsolete: card & paper punch, teletype
 present: VDU (visual display unit), printers, plotters, graphics
display, sound
 future: voice synthesis.
Lecture 1: Introduction
30

31. Basic Machine Software
 Software is the key to making computers general purpose.
 Software are often built hierarchically, with layers of
software providing successive higher-level of abstractions.
 This structure is reflected by the following onion layer
view of software.
Lecture 1: Introduction
31

32. Basic Machine Software
Hardware
Operating system
System utilities
Applications/User programs
Lecture 1: Introduction
32

33. Software – Flowcharts
 The sequence of instructions of a software/program can
be graphically specified using flowcharts.
flowcharts
 The flowchart technique maybe a little outdated but could
still be used in a clear manner for simple problems.
 As an example, the procedure to find the roots of a
quadratic equation, ax2 + bx + c = 0, can be written using
the following equation:
roots = (−b ± b 2 − 4ac ) / 2a
Lecture 1: Introduction
33

34. Software – Flowcharts
 This procedure can be coded in the following flowchart:
Read
a,b,c
roots = (−b ± b 2 − 4ac ) / 2a
a=0?
yes
Write
not quadratic
no
d:=b2 - 4ac
=
Write
real root
Lecture 1: Introduction
d>0
d=0
d<0
>
Write
real roots
<
Write
complex roots
34

35. Software – Languages
 All programs will have to be coded in some programming
language – usually text-based.
 The native language of machine is called machine
language.
language
 This consists of a set of primitive instructions, coded in
numbers.
 An example is "0310 0412 0512". But can you understand
what it does?
Lecture 1: Introduction
35

36. Software – Languages
 Possible to use more human-readable mnemonic
instructions.
 These are know as assembly language instructions.
Mnem onic
Descript ion
ADD 10
AC:= AC+ C(10)
SUB 12
AC:= AC-C(12)
STO 12
C(12)= AC
 Normally, assembly language has a 1-to-1
correspondence with machine language.
Lecture 1: Introduction
36

37. Software – Languages
 Assembly language is still very primitive.
 Higher-level Languages, like Pascal, C, Fortran, which are a
Languages
little closer to English language have been developed.
Lecture 1: Introduction
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38. Software – Languages
 An example Pascal program to find roots of quadratic
equation:
read(a,b,c);
if a=0
then writeln ("not a quadratic equation")
else
begin
d := sqr(b)-4*a*c;
if d>0 then writeln ("complex roots")
else if d=0 then writeln("single root =",-b/(2*a))
else writeln ("root1=",-b+sqrt(d)/(2*a),
"root2=", -b-sqrt(d)/(2*a));
end;
Lecture 1: Introduction
38

39. Software – Operating Systems
 Operating System (OS) is situated directly above
hardware. It controls and manages the available
hardware resources.
 Often, OS has special access privileges to certain
categories of instructions and certain hardware
 User programs have to go through OS for these privileges.
Lecture 1: Introduction
39

40. Software – Operating Systems
 Associated Functions/Tasks:
 boots up machine
 loads user program
 allocates main memory/storage space
 schedules concurrent user programs
 drivers to service various devices (terminals, printers, etc.)
Lecture 1: Introduction
40

41. Software – System Utilities
 Above the OS, there is a set of frequently executed
programs,called System Utilities. These utilities are often
Utilities
packaged with OS.
 Used by programmers/analyst to help develop applications.
 Some examples
 Editor: compose/edit user programs or data files
 Assembler: translates assembly to machine code
 Compiler: translates high-level language to assembler/machine
code
 Spooler: temporary stores print files for queuing
Lecture 1: Introduction
41

42. Software – System Utilities
 Some examples (continued)
 Mailer: forwards/receives mails between users
 DBMS (Data-Base Management System): centralised
management of data at a more abstract level than files
 Window Management System: multiple windows can appear on
single screen. These together with various graphical entities (e.g.
menus,panels, buttons) can be managed by WMS.
Lecture 1: Introduction
42

43. Software – Applications
 Word-Processors: compose/edit reports/articles
Word-Processors
 Accounting Package: keeps track of accounting
Package
transactions, produces daily/weekly/monthly (profit/loss)
reports
 Inventory System: keeps track of stock levels
System
 Personnel/Payroll System: staff records, monthly salary
System
CS1104-1
Lecture 1: Introduction
43

44. What’s in Computer & Network
Technology..?
Application (Netscape)
Software
Compiler
Assembler
Operating
System
(Windows XP)
Processor Memory I/O system
Datapath & Control
Hardware
CS1104-1
Instruction Set
Architecture
Computer Architecture
Digital Design
transistors
Lecture 1: Introduction
Digital Logic Design
44

45. Thank you
Lecture 1: Introduction
45