instruction set & assembly language

1. INSTRUCTION SET
OF 8085
By
K.THAMIZHSELVI
Asst. Prof. of CS

2. Instruction set of 8085
• An instruction is a binary pattern designed
inside a microprocessor to perform a specific
function.
• The entire group of instructions that a
microprocessor supports is called Instruction
Set.
• 8085 has 246 instructions.

3. Classification of Instruction Set
• Data Transfer Instruction
• Arithmetic Instructions
• Logical Instructions
• Branching Instructions
• Control Instructions

4. Addressing Modes
• Each instruction requires data on which it has
to operate.
– Direct Addressing – address of operand is given
directly.
– Register Addressing – specifies address of the
register
– Register Indirect Addressing – Address of the
operand is given by the register pair.
– Immediate Addressing – operand is specified
within the instruction itself.

5. STATUS FLAG
5 types:
• 1. Carry flag (CS)
• 2. Parity flag (P)
• 3. Auxiliary Carry flag (AC)
• 4. Zero flag (Z)
• 5. Sign flag (S)

6. ASSEMBLY LANGUAGE
• A Program written in Mnemonic code –
Assembly Language
• Mnemonic codes are alphanumeric symbols
easy and rememberable.
• Both machine and assembly language are
microprocessor specific one
• So called as Low Level Language.

7. ASSEMBLER
• A program translate assembly language into
machine language – Assembler
• Assembly language Assembler Machine language
Self assembler Cross Assembler
Self assembler – run on microcomputer for which it
produce object codes. (lack of speed)
Cross Assembler – run on computer other than that for
produce object codes (speed & time convenient)

8. One pass Assembler – Assembler goes through assembly
language only once
Two pass Assembler - Assembler goes through assembly
language twice
DISASSEMBLER
Machine language Disassembler Assembly language