Page 135 - Digital Electronics by harish

Arithmetic instructions

Arithmetic operations like addition, subtraction, increment and decrement
are performed by this category of instructions. One of the operand is taken from
the Accumulator and the other operand may be from registers or memory. The
result of the arithmetic operations is stored in the Accumulator. All the flags are
affected.

Examples : 1) ADD B ii) INR A

Logic and bit manipulation instructions

Logical functions like AND, OR and EX-OR are performed by this
instructions. All logic functions are performed in relation with the contents of
the Accumulator. All the flags are affected.

Examples : 1) ANA B ii) CMA

Branch instructions

Branch instructions change the sequence of the program execution
unconditionally or conditionally. The condition of flags is used to take the
decision for conditional branches. No flags are affected.

Examples : i) JMP 5000H ii) JNZ 5000H
Machine control instructions

The instructions dealing with interrupt handling and system operations
are classified into this category. No flags are affected.

Examples : 1) HLT ii) EI

5.2.4 Instruction set

5.2.4.1 Data Transfer Instructions

S.No Instruction Example
Move - Copy from source to destination
MOV Rd, Rs MOV B, C
MOV M, Rs MOV M, A
1. MOV Rd, M MOV B, M
This instruction copies the contents of the source register into the destination
register; the contents of the source register are not altered.

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