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Paper 2 - Computer Science > Instruction set > Flashcards

Flashcards in Instruction set Deck (14)
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1

What is an instruction set?

The set of machine code instructions that a specific processor can understand/execute

2

When can two different type of processors be compatible?

If they operate on the same instructions, use the same machine code

3

What are the two parts that make up a machine code instruction?

The opcode and the operand

4

What does the opcode state?

The opcode is the instruction to perform.

5

What does the operand state?

The operand is the value or memory address to be used

6

What are the two addressing modes?

Immediate and Direct Addressing

7

What is immediate addressing?

- The data in the operand is immediately available for use as it represents a value e.g. 6 or 187
- This is a very fast addressing mode

8

What is direct addressing?

- The data in the operand refers to a memory location
- Disadvantage is that code cannot be relocated

9

What is branching?

Branching is used for conditional statements or unconditional statements

10

What is a label?

A sequence of characters that identify a location in the source code

11

In operations what does the # symbol indicate

The # indicates that the operand is a number, uses immediate addression

No # indicates that the operand is a memory address.

12

What does the halt operation do?

It terminates the program operation.

13

How many bits may each machine code instruction occupy up to? (if it provides a diagram)

32 bits, usually 6 slots
if there are more or less slots just count up
for example if there are 5 slots do - 1 2 4 8 16, 16 is the 5th slot

14

How many different opcodes can be represented with 4 bits

2^4 = 16 different opcodes