15 - hardware

Question 1

CISC processors

Answer 1

Complex Instruction set computer
- uses more internal instruction formats
- carries out a task with as few lines of assembly code as possible
- hardware must therefore be able to handle complex instructions
- complex instructions are converted by the process into sub instructions to carry out the operation

Question 2

2 types of processors

Answer 2

RISC
CISC

Question 3

RISC processors

Answer 3

Reduced Instruction Set Computer
- fewer built in instruction formats
- uses less complex instructions - break up the code into a number of siimple single cylce instructions
- smaller, but more optimised instructions

Question 4

CISC features

Answer 4

• many instruction formats
• more addressing modes
• multi cycle instructions
• variable length instructions
• longer execution time
• more complex decoding
• hard to pipeline
• emphasis on hardware
• ## uses memory unit to allow complex instructions to be carries out

Question 5

RISC features

Answer 5

• less instruction formats/ sets
• fewer addressing modes
• single cycle instructions
• fixed length instructions
• faster execution time
• uses general multi- purpose registers
• easier to pipeline
• emphasis on software
• processor chips require fewer transistors

Question 6

pipelining

Answer 6

allows several instructions to be processed simultaneously without waiting for the previous instructions to be complete
- once program A has finished the first step of execution it moves to second step while B starts step 1 etc
- needs several regsters to store each stage

Question 7

how is execution of an instruction split

Answer 7

• instruction fetch cycle
• instruction decode cycle
• operand fetch cycle
• instruction execution cycle
• writeback result process

Question 8

interrupts

Answer 8

• once th eprocessor detects it
• the program is stopped if higher priority

Question 9

interrupts with pipelining