The document discusses the 8085 microprocessor instruction set. It introduces the 8085 instruction formats which can be single byte, double byte, or triple byte depending on the operation and operands. The single byte format only contains an opcode, while the double and triple byte formats contain opcodes and data or address operands. The document also notes some key features of the 8085 instruction set, including using the program counter to hold the next instruction address, using the accumulator as an operand and destination, and utilizing general purpose registers.

1. MICROPROCESSOR 8085
LECTURE 5
INTRODUCTION TO INSTRUCTION SET
PROF. SANDIP DAS

2. 00111010
00111010
00000000
01000111
00111010
00111011
00000000
10000000
00110010
00111100
00000000
01110110
Main
Memory
Machine
language
3A
3A
00
47
3A
3B
00
80
32
3C
00
76
LDA 003A
MOV B,A
LDA 003B
ADD B
STA 003C
HLT
Hexadecimal Mnemonics
Load
Accumulator
with address
003A
Move content of
A in register B
Load
Accumulator
with address
003BADD content of
A with register B
Store content of
A in address
003A
Halt
Operations

3. INSTRUCTION FORMATS
OPCODE
SOURCE
ADDRESS
OPERAND
1
SOURCE
ADDRESS
OPERAND
2
DESTINATIO
N ADDRESS
ADDRESS
OF NEXT
INSTRUCTIO
N1 BYTE 2 BYTE 2 BYTE 2 BYTE 2 BYTE =9 BYTESSIZE
• Use of Program counter to hold the Address of next
instruction.
• Use of Accumulator as one of the operand
• Use of Accumulator as destination address, i.e. keeping source
and destination address same
• Use of general purpose registers.
• Thus instead of using such a long format for Instruction, we
can reduce by using only opcode which increases time of
execution.

4. NUMBER OF BYTES
INSTRUCTION FORMATS
OPODE Single Byte
OPCODE
DATA/ADDRESS
Double Byte
OPCODE
DATA/ADDRESS
DATA/ADDRESS
Three Byte