Last changed: 29/09/2013
Dedicated Computer Systems –
Part 1
Syllabus
Notes
General purpose computer
Can a car become a plane or a plane become a car? In the world of
machines, each machine is usually built for a particular function, such as
getting you somewhere, washing your clothes or playing music. Computers
however are different because when a computer is built, the manufacturer
doesn’t know what it will be used for as everyone will use it for different
reasons.
Such a computer is called a general purpose computer, which is a
computer which is controlled by a program and the program can be easily
changed. It is not designed to be very good at a particular task. If you want
the computer to do something different, you just change the program that
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is running. For example, if you want the computer to become a typewriter,
you run a word processing program, if you want the computer to become a
jukebox, you run an mp3 player program.
Special purpose computer
A special purpose computer (or dedicated computer) on the other
hand is a computer which uses a program which is difficult to change. Such
a computer would be designed to be very good at some specific task and
usually does nothing else. Examples of this are DVD players, satellite
navigation systems and automatic teller machines (ATMs). Programs for
such a computer would probably only run on this type of computer.
Input and output for a special purpose computer need not be general
purpose like a mouse or monitor. Input and output for a special purpose
computer only needs to be used for one task and could be as simple as a
button, such as in a stopwatch, or a keypad, such as in an automatic teller
machine or a light bulb, such as in a burglar alarm, or an LCD numeric
display, such as in a calculator.
Embedded computers
An “embedded computer” is a special purpose computer which is part
of another machine, such as a computer inside a car, which might be used to
automatically park the car, or air conditioner, which might be used to
regulate the temperature. It is not used directly by the user; instead the
computer is there to be used by the machine which is itself used directly by
the user.
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Points
 General purpose computers are controlled by software which is
easy to change. Their input and output devices (keyboards,
monitors, etc.) can be used for many different unrelated things.
 Special purpose computers are controlled by software which is
difficult to change. Their input and output devices (buttons,
numeric displays, etc.) can be used for particular tasks only.
 Embedded computers are small computers which are used by
machines rather than people.
Further reading
 A Complete Computing Course
o Chapter 2.1
o Chapter 2.2.6
Past papers
On this topic only
 Paper IIB
o 2013: 1[f(i-ii)]
o 2012: 1[d]
 Paper I
o 2013: 8[e]
o 2011: 5
 Paper IIA
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Last changed: 29/09/2013
o 2012: 2[b]
o 2009: 6[d(i-ii)]
Mixed
 Paper IIB
o
 Paper I
o
 Paper IIA
o 2009: 6[d(iii)]
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This work is licensed under a Creative Commons Attribution 3.0 Unported License.