vonn neumann architecure

Question 1

What is stored program concept?

Answer 1

programs stored inside the computer that can be reprogrammed.

Question 2

What does a processing unit contain?

Answer 2

• an arithmetic logic unit
• processor registers

Question 3

What does a control unit contain?

Answer 3

• an instruction register
• a program counter
• memory that stores data + instructions
• external data storage
• input and output dates

Question 4

fetch:

Answer 4

• CPU fetches data and instructions from the RAM and saves it in registers
• memory address of the next item that the CPU wants is put on the address bus.
• data from this memory address travels from RAM on the data bus.

Question 5

decode:

Answer 5

the decode step involves the CPU and control unit working out what the instructions that it has just fetched actually mean.

Question 6

execute:

Answer 6

• when the data processing happens
• instructions are carried out on the data. some instructions are carried out by the ALU (adding, shifting, AND, OR)

Question 7

what is the clock

Answer 7

• determines the speed of the CPU. the chip uses a vibrating quartz crystal that maintains a constant rate of vibration.
• with every tick of the clock, the CPU fetches and executes one cycle.
• one cycle per second is known as 1 hertz.
• a CPU with a clock speed of 1 gigahertz can carry out one billion cycles per second.
• computer clocks have speeds of 3gz

Question 8

the CPU (central processing unit)

Answer 8

hardware component responsible for all the processing that the computer carries out. its job is to process data.

Question 9

the control unit

Answer 9

receives and sends signals to and from other components of the computer

responsible for handling hardware interrupts (eg. inputs from a mouse)

Question 10

the ALU

Answer 10

performs actual operations on data.

this encompasses + / = *, booleans/logic gates (AND, OR).

Question 11

registers:

Answer 11

extremely fast memory. located on the processor, and very very small.

bytes of data, aka immediate access storage.

it’s significantly faster than RAM as it doesn’t have to use buses.

Question 12

cache:

Answer 12

high-speed memory used to store frequently accessed data or instructions.

closer to the CPU than main memory for faster access, improving system performance

stores frequently accessed data, e.g. game texture packs, fonts

Question 13

instruction register

Answer 13

holds instructions executed by CPU

Question 14

accumulator

Answer 14

holds ALU vales

Question 15

program counter

Answer 15

holds the memory address of the next instruction to be fetched, like a person holding a flag

Question 16

pipelining

Answer 16

a method of keeping all the components busy to improve overall CPU performance.

• an instruction completed every clock cycle, increases CPU throughout, optimising system performance
• a CPU is fully pipelined if a fetch can be carried out every clock cycle.

Question 17

data bus

Answer 17

carries binary data from component to component. bidirectional

Question 18

control bus:

Answer 18

carries signals that control the CPU components. bidirectional

Question 19

address bus:

Answer 19

carries the address of a memory location. unidirectional

Question 20

bus:

Answer 20

physical connection used to connect computer components to hardware and transfer data along them.

Question 21

RAM

Answer 21

random access memory
read and write
stores instructions and data for the CPU to execute
if not enough, computer slowed down
volatile
1-256GB

Question 22

ROM

Answer 22

read only memory
stores permanent instructions that start boot up
non volatile
6-8MB

Question 23

solid state

Answer 23

no moving parts -> silent
lifespan 5y due to solid state degradation
stores data in electronic circuits
smaller than magnetic
larger but more expensive
fast read and write
non volatile

Question 24

optical

Answer 24

distributes media and software
uses lasers to read and write data on reflective surface
small in capacity but cheap to make

Question 25

magnetic

Answer 25

stored in polarised dots - positive = 1 and negative = 0
very large capacity and inexpensive
large moving parts
lifespan until dots no longer polarised