2. 8085 introduction to instruction
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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.
2. 8085 introduction to instruction
- 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