Page 133 - DCAP210_INTRODUCTION__TO_MICROPROCESSORS

Unit 9: Introduction to 8085 Instructions

Increment/Decrement: The 8-bit contents of a register or a memory location can be incremented Notes
or decrement by 1. Similarly, the 16-bit contents of a register pair (such as BC) can be incremented
or decrement by 1. These increment and decrement operations differ from addition and subtraction
in an important way; i.e., they can be performed in any one of the registers or in a memory
location.
The arithmetic instructions add, subtract, increment, or decrement data in registers or memory.
ADD: Add to Accumulator

ADI: Add Immediate Data to Accumulator
ADC: Add to Accumulator Using Carry Flag
ACI: Add Immediate data to Accumulator Using Carry
SUB: Subtract from Accumulator

SUI: Subtract Immediate Data from Accumulator
SBB: Subtract from Accumulator Using Borrow (Carry) Flag
SBI: Subtract Immediate from Accumulator Using Borrow (Carry) Flag

INR: Increment Specified Byte by One
DCR: Decrement Specified Byte by One
INX: Increment Register Pair by One
DCX: Decrement Register Pair by One

DAD: Double Register Add; Add Content of Register
Pair to H & L Register Pair

Write an assembly program to implement subtraction on two numbers.

9.3 Logical Operations
These instructions perform various logical operations with the contents of the accumulator. AND,
OR Exclusive-OR - Any 8-bit number, or the contents of a register, or of a memory location can be
logically ANDed, Ored, or Exclusive-ORed with the contents of the accumulator. The results are
stored in the accumulator. Rotate- Each bit in the accumulator can be shifted either left or right to
the next position. Compare- Any 8-bit number or the contents of a register, or a memory location
can be compared for equality, greater than, or less than, with the contents of the accumulator.
Complement - The contents of the accumulator can be complemented. All 0s are replaced by 1s
and all 1s are replaced by 0s.

The logical AND, OR, and Exclusive OR instructions enable you to set specific bits
in the accumulator ON or OFF.

ANA: Logical AND with Accumulator

ANI: Logical AND with Accumulator Using Immediate Data
ORA: Logical OR with Accumulator
OR: Logical OR with Accumulator Using Immediate Data

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