Chapter 4

Question 1

Arithmetic logic unit (ALU)

Answer 1

component in the
processor which carries out all arithmetic and logical
operations.

Question 2

Control unit

Answer 2

ensures synchronisation of data flow
and programs throughout the computer by sending out
control signals along the control bus.

Question 3

System clock

Answer 3

produces timing signals on the control

bus to ensure synchronisation takes place.

Question 4

Accumulator

Answer 4

temporary general purpose register
which stores numerical values at any part of a given
operation.

Question 5

Register

Answer 5

temporary component in the processor
which can be general or specific in its use that holds
data or instructions as part of the fetch-execute cycle.

Question 6

Address bus

Answer 6

carries the addresses throughout the

computer system.

Question 7

Data bus

Answer 7

allows data to be carried from processor to
memory (and vice versa) or to and from input/output
devices.

Question 8

Control bus

Answer 8

carries signals from control unit to all

other computer components.

Question 9

BIOS

Answer 9

basic input/output system.

Question 10

Cache memory

Answer 10

a high speed auxiliary memory which

permits high speed data transfer and retrieval.

Question 11

Universal Serial Bus (USB)

Answer 11

a type of port connecting

devices to a computer.

Question 12

Port

Answer 12

external connection to a computer which allows
it to communicate with various peripheral devices. A
number of different port technologies exist.

Question 13

Program counter (PC)

Answer 13

a register used in a computer
to store the address of the instruction which is
currently being executed.

Question 14

Current instruction register

Answer 14

a register used to
contain the instruction which is currently being
executed or decoded.

Question 15

Machine code

Answer 15

the programming language that the

CPU uses.

Question 16

Instruction

Answer 16

a single operation performed by a CPU.

Question 17

Assembly language

Answer 17

a low-level chip/machine specific

programming language that uses mnemonics.

Question 18

Opcode

Answer 18

short for operation code, the part of a
machine code instruction that identifies the action the
CPU will perform.

Question 19

Operand

Answer 19

the part of a machine code instruction that

identifies the data to be used by the CPU.

Question 20

Source code

Answer 20

a computer program before translation

into machine code.

Question 21

Absolute addressing

Answer 21

mode of addressing in which
the contents of the memory location in the operand are
used.

Question 22

Direct addressing

Answer 22

mode of addressing in which the
contents of the memory location in the operand are
used, which is the same as absolute addressing.

Question 23

Indirect addressing

Answer 23

mode of addressing in which the
contents of the contents of the memory location in the
operand are used.

Question 24

Indexed addressing

Answer 24

mode of addressing in which the
contents of the memory location found by adding the
contents of the index register (IR) to the address of the
memory location in the operand are used.

Question 25

Immediate addressing

Answer 25

mode of addressing in which

the value of the operand only is used.

Question 26

Relative addressing

Answer 26

mode of addressing in which the
memory address used is the current memory address
added to the operand.

Question 27

Symbolic addressing

Answer 27

mode of addressing used in
assembly language programming, where a label is used
instead of a value.

Question 28

Shift

Answer 28

moving the bits stored in a register a given number of places within the
register; there are different types of shift.

Question 29

Logical shift

Answer 29

bits shifted out of the register are replaced with zeros.

Question 30

Arithmetic shift

Answer 30

the sign of the number is preserved.

Question 31

Cyclic shift

Answer 31

no bits are lost, bits shifted out of one end of the register are introduced
at the other end of the register.

Question 32

Left shift

Answer 32

bits are shifted to the left.

Question 33

Right shift

Answer 33

bits are shifted to the right.

Question 34

Monitor

Answer 34

to automatically take readings from a device.

Question 35

Control

Answer 35

to automatically take readings from a device, then use the data from those
readings to adjust the device.

Question 36

Mask

Answer 36

a number that is used with the logical operators AND, OR or XOR to identify,
remove or set a single bit or group of bits in an address or register.