INTRODUCTION TO COMPUTER & MICROPROCESSOR
What is a Computer?
A computer is an electronic machine that accepts information, stores it until the
information is needed, processes the information according to the instructions provided by the
user, and finally returns the results to the user. The computer can store and manipulate large
quantities of data at very high speed, but a computer cannot think. A computer makes decisions
based on simple comparisons such as one number being larger than another. Although the
computer can help solve a tremendous variety of problems, it is simply a machine. It cannot
solve problems on its own.
Computer Generations
From the 1950’s, the computer age took off in full force. The years since then have been
divided into periods or generations based on the technology used.
Table (1.1): Generations of computer
Generation Technology & Architecture Software & Applications Systems
Machine & Assembly
Vacuum tubes, Relay memories, CPU
First language, Single user Basic ENIAC TIFRAC
driven by PC and accumulator; fixed
(1945‐54) I/O using programmed IBM 701 Princeton IAS
point Arithmetic
and Internet mode.
Discrete Transistors, Core Memories, HLL used with compilers, IBM7099
Second (1955‐
Floating point, Arithmetic I/O, batch processing,
64)
processors, Multiplexed memory access Monitoring, Libraries CDC 1604
Integrated circuits, Microprogramming, Multiprogramming, Time IBM 360/700
Third
Pipelining, Caching, Lookahead sharing OS, Multi‐user CDC 6000
(1965‐71)
Processing applications TA‐ASC PDP‐8
VAX 9800, Cray X‐MP,
LSI/VLSI and Semiconductor memory,
IBM 3600, Pentium
Fourth Microprocessors technology, Multiprocessor OS,
Processor based
(1971‐Present) Multiprocessors, vector super‐ languages, Compilers
systems (PCs), Ultra
computing, multi computer
SPARC
Fifth parallel processing, Cray/MPP, TMC/CM‐5,
artificial intelligence and still in
(present & superconductors, voice Intel paragon, Fujitsu
Beyond)
development, VP500
recognition Applications
-1-
,Types of Computers
Computer now comes in a variety of shapes and sizes, which could be roughly classified
according to their processing power into five sizes: super large, large, medium, small, and tiny.
Microcomputers are the type of computers that we are most likely to notice and use in our
everyday life. In fact there are other types of computers that you may use directly or indirectly:
Supercomputers‐super large computers: supercomputers are high‐ capacity machines
with hundreds of thousands of processors that can perform more than 1 trillion
calculations per second. These are the most expensive but fastest computers available.
"Supers," as they are called, have been used for tasks requiring the processing of
enormous volumes of data, such as doing the U.S. census count, forecasting weather,
designing aircraft, modeling molecules, breaking codes, and simulating explosion of
nuclear bombs.
Mainframe computers ‐ large computers: The only type of computer available
until the late 1960s, mainframes are water‐ or air‐cooled computers that vary in size
from small, to medium, to large, depending on their use. Small mainframes are often
called midsize computers; they used to be called minicomputers. Mainframes are used
by large organizations such as banks, airlines, insurance companies, and colleges‐for
processing millions of transactions. Often users access a mainframe using a terminal,
which has a display screen and a keyboard and can input and output data but cannot by
itself process data.
Workstations ‐ medium computer: Introduced in the early 1980s, workstations, are
expensive, powerful computers usually used for complex scientific, mathematical, and
engineering calculations and for computer‐aided design and computer‐aided
manufacturing. Providing many capabilities comparable to midsize mainframes,
workstations are used for such tasks as designing airplane fuselages, prescription drugs,
and movie special effects. Workstations have caught the eye of the public mainly for
their graphics capabilities, which are used to breathe three‐dimensional life into movies
such as Jurassic Park and Titanic. The capabilities of low‐end workstations overlap those
of high‐end desktop microcomputers.
-2-
, Microcomputer ‐ small computers: Microcomputers, also called personal computers (PC),
can fit next to a desk or on a desktop, or can be carried around. They are either stand‐
alone machines or are connected to a computer network, such as a local area network. A
local area network (LAN) connects, usually by special cable, a group of desktop PCs and
other devices, such as printers, in an office or a building. Microcomputers are of several
types:
Desktop PCs: are those in which the case or main housing sits on a desk, with
keyboard in front and monitor (screen) often on top.
Tower PCs: are those Microcomputer in which the case sits as a "tower," often on the
floor beside a desk, thus freeing up desk surface space.
Laptop computers (also called notebook computers): are lightweight portable
computers with built‐in monitor, keyboard, hard‐disk drive, battery, and AC adapter
that can be plugged into an electrical outlet; they weigh anywhere from 1.8 to 9
pounds.
Personal digital assistants (PDAs) (also called handheld computers or palmtops)
combine personal organization tools‐schedule planners, address books, to‐do lists.
Some are able to send e‐mail and faxes. Some PDAs have touch‐sensitive screens. Some
also connect to desktop computers for sending or receiving information.
Microcontrollers‐tiny computers: Microcontrollers, also called embedded computers,
are the tiny, specialized microprocessors installed in "smart" appliances and
automobiles. These microcontrollers enable PDAs microwave ovens, for example, to
store data about how long to cook your potatoes and at what temperature.
Basic Blocks of a Microcomputer
All Microcomputers consist of (at least):
1. Microprocessor Unit (MPU) MPU is the brain of microcomputer
2. Program Memory (ROM)
3. Data Memory (RAM)
4. Input / Output ports
5. Bus System
-3-
, Fig. (1.1): Basic Block of a Microcomputer
Input Units ‐‐ "How to tell it what to do"
Devices allow us to enter information into the computer. A keyboard and mouse
are the standard way to interact with the computer. Other devices include mice,
scanners, microphones, joysticks and game pads used primarly for games.
Output Units ‐‐ "How it shows you what it is doing"
Devices are how the manipulated information is returned to us. They commonly
include video monitors, printers, and speakers.
Bus System
A Bus is a common communications pathway used to carry information between the
various elements of a computer system
The term BUS refers to a group of wires or conduction tracks on a printed circuit
board (PCB) though which binary information is transferred from one part of the
microcomputer to another
The individual subsystems of the digital computer are connected through an
interconnecting BUS system.
There are three main bus groups
ADDRESS BUS
DATA BUS
CONTROL BUS
-4-
What is a Computer?
A computer is an electronic machine that accepts information, stores it until the
information is needed, processes the information according to the instructions provided by the
user, and finally returns the results to the user. The computer can store and manipulate large
quantities of data at very high speed, but a computer cannot think. A computer makes decisions
based on simple comparisons such as one number being larger than another. Although the
computer can help solve a tremendous variety of problems, it is simply a machine. It cannot
solve problems on its own.
Computer Generations
From the 1950’s, the computer age took off in full force. The years since then have been
divided into periods or generations based on the technology used.
Table (1.1): Generations of computer
Generation Technology & Architecture Software & Applications Systems
Machine & Assembly
Vacuum tubes, Relay memories, CPU
First language, Single user Basic ENIAC TIFRAC
driven by PC and accumulator; fixed
(1945‐54) I/O using programmed IBM 701 Princeton IAS
point Arithmetic
and Internet mode.
Discrete Transistors, Core Memories, HLL used with compilers, IBM7099
Second (1955‐
Floating point, Arithmetic I/O, batch processing,
64)
processors, Multiplexed memory access Monitoring, Libraries CDC 1604
Integrated circuits, Microprogramming, Multiprogramming, Time IBM 360/700
Third
Pipelining, Caching, Lookahead sharing OS, Multi‐user CDC 6000
(1965‐71)
Processing applications TA‐ASC PDP‐8
VAX 9800, Cray X‐MP,
LSI/VLSI and Semiconductor memory,
IBM 3600, Pentium
Fourth Microprocessors technology, Multiprocessor OS,
Processor based
(1971‐Present) Multiprocessors, vector super‐ languages, Compilers
systems (PCs), Ultra
computing, multi computer
SPARC
Fifth parallel processing, Cray/MPP, TMC/CM‐5,
artificial intelligence and still in
(present & superconductors, voice Intel paragon, Fujitsu
Beyond)
development, VP500
recognition Applications
-1-
,Types of Computers
Computer now comes in a variety of shapes and sizes, which could be roughly classified
according to their processing power into five sizes: super large, large, medium, small, and tiny.
Microcomputers are the type of computers that we are most likely to notice and use in our
everyday life. In fact there are other types of computers that you may use directly or indirectly:
Supercomputers‐super large computers: supercomputers are high‐ capacity machines
with hundreds of thousands of processors that can perform more than 1 trillion
calculations per second. These are the most expensive but fastest computers available.
"Supers," as they are called, have been used for tasks requiring the processing of
enormous volumes of data, such as doing the U.S. census count, forecasting weather,
designing aircraft, modeling molecules, breaking codes, and simulating explosion of
nuclear bombs.
Mainframe computers ‐ large computers: The only type of computer available
until the late 1960s, mainframes are water‐ or air‐cooled computers that vary in size
from small, to medium, to large, depending on their use. Small mainframes are often
called midsize computers; they used to be called minicomputers. Mainframes are used
by large organizations such as banks, airlines, insurance companies, and colleges‐for
processing millions of transactions. Often users access a mainframe using a terminal,
which has a display screen and a keyboard and can input and output data but cannot by
itself process data.
Workstations ‐ medium computer: Introduced in the early 1980s, workstations, are
expensive, powerful computers usually used for complex scientific, mathematical, and
engineering calculations and for computer‐aided design and computer‐aided
manufacturing. Providing many capabilities comparable to midsize mainframes,
workstations are used for such tasks as designing airplane fuselages, prescription drugs,
and movie special effects. Workstations have caught the eye of the public mainly for
their graphics capabilities, which are used to breathe three‐dimensional life into movies
such as Jurassic Park and Titanic. The capabilities of low‐end workstations overlap those
of high‐end desktop microcomputers.
-2-
, Microcomputer ‐ small computers: Microcomputers, also called personal computers (PC),
can fit next to a desk or on a desktop, or can be carried around. They are either stand‐
alone machines or are connected to a computer network, such as a local area network. A
local area network (LAN) connects, usually by special cable, a group of desktop PCs and
other devices, such as printers, in an office or a building. Microcomputers are of several
types:
Desktop PCs: are those in which the case or main housing sits on a desk, with
keyboard in front and monitor (screen) often on top.
Tower PCs: are those Microcomputer in which the case sits as a "tower," often on the
floor beside a desk, thus freeing up desk surface space.
Laptop computers (also called notebook computers): are lightweight portable
computers with built‐in monitor, keyboard, hard‐disk drive, battery, and AC adapter
that can be plugged into an electrical outlet; they weigh anywhere from 1.8 to 9
pounds.
Personal digital assistants (PDAs) (also called handheld computers or palmtops)
combine personal organization tools‐schedule planners, address books, to‐do lists.
Some are able to send e‐mail and faxes. Some PDAs have touch‐sensitive screens. Some
also connect to desktop computers for sending or receiving information.
Microcontrollers‐tiny computers: Microcontrollers, also called embedded computers,
are the tiny, specialized microprocessors installed in "smart" appliances and
automobiles. These microcontrollers enable PDAs microwave ovens, for example, to
store data about how long to cook your potatoes and at what temperature.
Basic Blocks of a Microcomputer
All Microcomputers consist of (at least):
1. Microprocessor Unit (MPU) MPU is the brain of microcomputer
2. Program Memory (ROM)
3. Data Memory (RAM)
4. Input / Output ports
5. Bus System
-3-
, Fig. (1.1): Basic Block of a Microcomputer
Input Units ‐‐ "How to tell it what to do"
Devices allow us to enter information into the computer. A keyboard and mouse
are the standard way to interact with the computer. Other devices include mice,
scanners, microphones, joysticks and game pads used primarly for games.
Output Units ‐‐ "How it shows you what it is doing"
Devices are how the manipulated information is returned to us. They commonly
include video monitors, printers, and speakers.
Bus System
A Bus is a common communications pathway used to carry information between the
various elements of a computer system
The term BUS refers to a group of wires or conduction tracks on a printed circuit
board (PCB) though which binary information is transferred from one part of the
microcomputer to another
The individual subsystems of the digital computer are connected through an
interconnecting BUS system.
There are three main bus groups
ADDRESS BUS
DATA BUS
CONTROL BUS
-4-
