Instruction Groups (Cambridge (CIE) A Level Computer Science) : Revision Note

Data Movement

LOAD

A

Loads the value stored at memory location A into the accumulator.

STORE

B

Stores the value from the accumulator into memory location B.

MOV

A, B

Copies the value from register/memory A to register/memory B.

CLEAR

ACC

Clears the accumulator (sets it to 0).

DATA

5

Declares a constant or data value (e.g. DATA 5 stores the value 5).

Input and Output of Data

IN

Takes input from a user or input device and stores it in the accumulator.

OUT

Outputs the value in the accumulator to a screen or output device.

Arithmetic Operations

ADD

A

Adds the value at memory location A to the accumulator.

SUB

B

Subtracts the value at memory location B from the accumulator.

INC

Increments the accumulator by 1.

DEC

Decrements the accumulator by 1.

Unconditional and Conditional

JMP

LABEL

Unconditionally jumps to the instruction at LABEL.

JZ

LABEL

Jumps to LABEL if the accumulator is zero.

JNZ

LABEL

Jumps to LABEL if the accumulator is not zero.

JC

LABEL

Jumps to LABEL if the carry flag is set.

HLT

Stops the program (halts execution).

Compare Instructions

CMP

A

Compares the accumulator with the value at memory location A.

TEST

A

Performs a logical AND between accumulator and A; sets flags, no output.