[Semester 2] ISA and Assembly

Question 1

Instruction Set Architecture (ISA)

Answer 1

Defines how a machine behaves. It also aims to execute instructions efficiently (i.e. less gates)

Question 2

Instruction sets

Answer 2

Patterns of bits designed by the designer of the processor

Question 3

Opcode

Answer 3

Holds which operation is being performed and how the result will be processed

Question 4

Operand

Answer 4

Holds data in an operation which needs to be acted on

Question 5

Flag

Answer 5

Indicates whether an operand is from memory

Question 6

Complex Instruction Set Computer (CISC)

Answer 6

Aims to execute code in as few assembly lines as possible

Question 7

Reduced Instruction Set Computer (RISC)

Answer 7

Like CISC but with separate load and store instructions

Question 8

Why might more RAM be needed when using RISC?

Answer 8

Instruction length is always the same, which can result in more lines than CISC

Question 9

True or false: RISC instructions can be executed in one clock cycle

Answer 9

True! This means that less transistors are needed.

Question 10

How many statements per instruction can assembly language have?

Answer 10

1

Question 11

Fetch

Answer 11

An instruction is retrieved from the memory address, which is stored in the program counter then the instruction register. The program counter then moves to the next instruction.

Question 12

Decode

Answer 12

A decoder decodes and interprets the instruction in the instruction register

Question 13

Execute

Answer 13

Control unit sends the decoded instruction as a sequence of signals to relevant parts of the CPU