2.3.1 Architecture

Question 1

Inputs

Answer 1

Keyboard
Mouse
Sensors

Computers take data
Process information (CPU)
Output information
Monitor or screen

Question 2

CPU

Answer 2

Brain of the computer

• fetches instructions from RAM
• decodes instructions
• executes
• contains all other parts of hardware system - hard drives graphics sounds

Question 3

What does the CPU contain

Answer 3

• control unit
• ALU
• registers
• CACHE memory
• modern computers have several CPUs

Question 4

control Unit

Answer 4

• sends signals to control movement of data along busses
• controls how instructions are sequences in fetch execute cycle
• directs other parts of the system by sending control signals

Question 5

ALU

Answer 5

Does the maths
Logical
Mathematical

Question 6

Registers

Answer 6

• part of CPU
• immediate access store
• memory locations used to help control unit execute lines of code
• work at high speeds
• used in fetch execute cycle

Question 7

Special purpose registers

Answer 7

• program counter- used to store address in memory RAM of next line of code to be executed
• MAR- location in memory of next line of code
• MDR- holds data held in the address from MAR that is waiting to be executed
• CIR- holds line of code processor currently executing

Question 8

CACHE memory

Answer 8

• form of RAM that can be read/ written to at much higher speed
• located inside CPU
• stores instructions that CPU most frequently needs.

Question 9

Program counter

Answer 9

Stores address in memory RAM of next line of code to be executed

Question 10

MAR

Answer 10

Location in memory of next line of code

Question 11

MDR

Answer 11

Holds data held in the address from MAR that is waiting to be executed

Question 12

CIR

Answer 12

holds line of code processor currently executing.

Question 13

Busses

Answer 13

Communication channels that allow data to flow between computer and components.

• channels that connect all the internal part of CPU together
• and CPU to other parts of the computer
• allow data to be sent and received as pulses of data

Question 14

Address bus

Answer 14

• sends the address of the location in memory needed by the CPU
• data only flows in one direction

Carries the location in memory to be accessed for reading writing data

Question 15

Data bus

Answer 15

Carries instructions or data between memory and CPU

Bidirectional flow

Question 16

Control bus

Answer 16

Control signals can be sent back and fourth between processor and memory

Question 17

Fetch execute cycle

Answer 17

Process used by a computer to retrieve a program instruction from memory, determine what instruction is expected to do and then carry out the actions associated with that instruction.

Question 18

Process of fetch execute cycle

Answer 18

• load address into PC
• copy PC to MAR
• increment PC
• load data into MDR
• transfer data to CIR
• execute instruction in CIR

Question 19

Input- output ports

Answer 19

Allow data to be transferred to or from peripheral devices to internal components of a computer.

Serial port
Parallel port
USB

Question 20

Serial port

Answer 20

Bidirectional
- transmits one data bit at a time across a single wire.
Mainly for connections to mice and modems.

Question 21

Parallel port

Answer 21

• sends all 8 bits at once over 8 wires in parallel

- connect old printers

Question 22

USB

Answer 22

• sends data 1 bit at a time
• bidirectional
• provide high speeds
• connect most peripherals

Question 23

Input/ output controllers

Answer 23

• connect busses to ports

- translates messages back and fourth between busses and peripheral

Question 24

The clock

Answer 24

• small quartz crystal located in memory
• synchronises all computers instructions
• sends signal or pulse on a regular basis to all other computer components.

Question 25

Factors influencing speed of processing

Answer 25

CLOCK SPEED- Increasing no. Of clock cycles per second means more instructions executed per second on motherboard.
- increasing clock speed not recommended as overheat internal component.
CACHE SIZE- instructions held in Cache are those CPUneeds most often.
- in cache- can be used at high speeds.
- more cache= instructions needed to operate faster can be accessed faster
PROCESSOR TYPE- processes with more cores will operate faster
- some offer 64 bit processing over 32 bit.

Question 26

What is a port

Answer 26

A physical connection where peripherals can be connected to enable data transfer between devices and the processor.

Question 27

Purpose of I/ O controllers in computer system

Answer 27

Busses control, send/ receive data
Component used to connect busses and ports (I/O)
The I/ O controller is between internal computer buses and port which communicates with external device.
Translates messages back and forth- between computer buses and the peripheral device.

Question 28

Role of a processor during operation of a computer program

Answer 28

Consists of the CU series of registers and ALU
Fetched instructions from RAM
Decodes instructions
Controls hard drives, graphics, sound
Modern computers can have many CPU’s.
Act together to provide greater processing power.

Question 29

How busses used in fetch execute cycle

Answer 29

Read signal sent via control bus to memory
Data transferred from memory to MDR via data bus.
First instruction address is loaded in to the program counter.
Contents are placed in MAR before the data can be accessed.
PC immediately updated to point to next location of instruction to be executed.
After being transferred by buses, instructions are copied in CIR where it is decided and executed by CPU.

Question 30

How clock speed affects processing speed of computer.

Answer 30

If CPU requires specific number of clock cycles to execute instructions- increasing the clock rate can increase the number of instructions executed per second.
CPUs can be “over clocked”

Question 31

Impact of different types of processor in speed of a computer system

Answer 31

RISC- smaller number of instructions at its disposal
During processing have to combine many simple instructions- an increased number of fetch execute cycles needed to carry out complex tasks- showing down speed of processing.