INSTRUCTION WORD SIZE

• 8085 is an 8-bit microprocessor.

• It can handle 8-bits at a time.

• The memory location of 8085 microprocessor can accommodate 8-bits of data.

• To store 16-bits data, they are stored in two consecutive memory locations.

• The word length of an instruction can be :

• 1 byte / 1 word

• 2 bytes / 2 words

• 3 bytes / 3 words

1 - Byte Instructions

• They include opcode and operands in the same byte.

• Operands are internal registers and coded into the instruction.

• Instructions require one memory location to store single byte in the memory.

2 - Byte Instructions

• 1st byte specifies opcode and 2nd byte specifies operand.

• Instructions require two memory locations to store in the memory.

3 - Byte Instructions

• 1st byte specifies opcode and 2nd & 3rd bytes specifies 16-bit address

• 2nd byte holds the low order address. 

• 3rd byte hods the high order address.

• Instructions require three memory locations to store single byte in the memory.