central processing unit architecture

Question 1

purpose and roles of the control unit

Answer 1

–directs and co-ordinates other parts of computer system
–controls operations of computer system
–fetches computer instructions
–decodes each instructions
–executes these instruction.

Question 2

purpose and roles arithmetic logic unit

Answer 2

– a unit which performs arithmetic operations
–and bit shifting operations
– logic operation(AND,OR,XOR)
–designed to perform integer calculation

Question 3

define operand

Answer 3

part of the computer instruction which specifies what data is to be processed

Question 4

define opcode

Answer 4

is the instruction that is executed by the cpu

Question 5

purpose and role of registers

Answer 5

–small piece of memory
–part of the processor
–temporary storage of data which is about to or had been processed

Question 6

difference between general purpose and special purpose registers

Answer 6

general purpose registers holds the temporary data while performing difference operations.

special purpose registers holds the status of a program

Question 7

define program counter

Answer 7

stores the address of next instruction to be fetched

Question 8

define MAR

Answer 8

stores memory address where data is to be read from

Question 9

define MDR

Answer 9

stores data that has just been read from memory

Question 10

define CIR

Answer 10

stores the instruction that is currently being executed

Question 11

define IX

Answer 11

index register used for indirect addressing .

Question 12

define ACC

Answer 12

(accumulator) is the register where the data is worked on (general purpose register).

Question 13

define status register

Answer 13

is interpreted as independent flags each flag is set depending on an event .

Question 14

purpose and role of a system clock

Answer 14

–every computer contains an internal clock that regulates the rate at which the instruction are executed
–CPU requires a fixed number of clocks cycles that executes each instructions
– used to synchronize all the operation.

Question 15

state the various components of the computer system that transfers data

Answer 15

–data bus
–address bus
–control bus

Question 16

define data bus

Answer 16

–carries data between processor and memory
–bi-directional bus
– used to exchange data

Question 17

define address bus

Answer 17

–uni- directional
–that carries signal related to memory address
– between processor and memory

Question 18

define control bus

Answer 18

–transmits signals between control unit and other components
–bi-directional

Question 19

what are the factors affecting the computer performance

Answer 19

–data bus width
–clock speed
–cache memory
–number of cores

Question 20

define how the data bus width affects performance

Answer 20

– the width of a bus determines the number of bits that can be simultaneously transferred
–increasing the width of a data bus increases the number of bits that can be transferred
– hence improve processing speed as fewer transfers are needed

Question 21

define how the clock speed affects performance

Answer 21

–one F-E cycle is run on each clock pulse
–so the clock speed dictates the number of instructions that can be run per second
–the faster the clock speed the more instructions can be run per second

Question 22

define how the cache memory affects performance

Answer 22

can also improve processor performance , it is similar to RAM, cache uses SRAM so they have faster access time as there is no need to keep refreshing. cache memory stores frequently used instructions and data that needs to be accessed faster , this improves processor performance

Question 23

define how the number of cores affects performance

Answer 23

–each core processes one instruction per clock pulse
–more cores mean that sequence of instructions can be split between them and so more than one instruction is executes per clock pulse
–more cores decreases the time taken to complete task

Question 24

define a port

Answer 24

acts as an interference between computers and other peripheral devices. female part of connection

Question 25

benefits of connecting peripheral devices using a USB port

Answer 25

– fast data transfer
useful when transferring large files such as video files

–automatic connection/plug and play
so usually there is no need to install separate drivers

–USB is now an industrial standard
all new computers will be equipped by USB port

–device may be powered or changed through USB
external devices could be charged while working at the computer

Question 26

use of HDMI cables

Answer 26

– helps to connect more monitors
– hdmi ports allow to output both audio and visual
–they support high definition signals
–faster data transfer
–hdmi increases the bandwidth making it possible to supply the necessary data for high quality sound and visual effects

Question 27

advantages of HDMI

Answer 27

– current standard for modern televisions and monitors.
–allows for a very fast data transfer rate
–improved security, helps prevent privacy by the help of HDCP
–supports modern digital system

Question 28

disadvantages of HDMI

Answer 28

–not a very robust connection(easy to break connection when simply moving devices)
–limited cable length

Question 29

advantages of VGA

Answer 29

–simpler technology
–only one standard available
–easy to split the signals and connect a number of devices from one source
–the connection is very secure
–VGA supports a higher refresh rate

Question 30

disadvantages of VGA

Answer 30

– it does not support audio
–outdated as modern laptops and computers rarely have a VGA port
–easy to bend the pins when making connections

Question 31

describe the process fetch-execute cycle

Answer 31

– pc holds the address of the next instruction to be fetched
– the address in program counter is copied to MAR
–program counter is incremented
–the instruction is copied from address stored in MAR to MDR.
–then instruction from the MDR is copied to CIR

Question 32

instructions of the F-E cycle

Answer 32

MAR<=[PC]
PC<=[PC]+1
MDR<=[[MAR]]
CIR<=[MDR]

Question 33

state the purpose of double brackets

Answer 33

the contents of MAR is an address , it is the contents of that address which is transferred to MDR

Question 34

what is meant by interrupt

Answer 34

a signal from source/device
telling the processor that its attention is needed

Question 35

example of hardware interrupt

Answer 35

printer out of paper

Question 36

example of software interrupt

Answer 36

run-time error
a running program needs input