The CPU contains the ALU for calculations, control unit for operations timing/ordering, and registers for temporary data storage. The control unit sends signals along the control bus, addresses along the address bus, and data is moved between components along the data bus. Memory stores programs and data at locations identified by addresses.

1. Computer Architecture

2. CPU
At the heart of every computer is the
CPU (Central Processing Unit)
This is the 'brain' of the computer.
It refers to that part of the processor which
'processes' the data and instructions.

3. The main part of the CPU
• The ALU (Arithmetic and Logic Unit) - which
performs the calculations on the data.
• The Control Unit - which controls all
operations inside the computer.
• A register is a place where a single item of
data can be stored. (some memory)

4. • All computers will have at least one input
device (eg keyboard, mouse), and at least one
output device (eg monitor).
• All computers have some memory. Both the
program a computer is running as well as the
data are all stored in memory.
(Eg When you write a letter using a word processor then both the word
processing program and the letter are stored in memory).

5. Random Access Memory (RAM)
This is the type of memory used for
temporarily storing programs and data
Memory consists of a large number of storage locations
in which data can be stored.
Each location is identified by an address.

6. Memory consists of a large number of storage
locations in which data can be stored. Each
location is identified by an address.
Data will need to be moved between several of
these elements. The path along which data
moves is called a data bus.

7. Data bus
Data will need to be moved between several of
these elements.
The path along which data moves is called a
data bus.

8. Address Bus
When data is saved to (or loaded from) memory,
the address of the store location at which it is
to be stored (or loaded) must also be sent.
The address of
data always
travels along
an address bus.

9. Control Unit
The Control Unit sends and receives signals from all
parts of the computer which makes sure that all
processes take place at the right time and in the
correct order. These signals travel along a control
bus.

10. Question Jan 2009
• Describe the main functions of the following
components of a computer:
A) Control unit
B) ALU
C) Register
D) Data Bus
E) Control Bus
F) Address Bus
“Single word or short phrased answers are not
acceptable”