8085 Instructions can be classified based on the addressing mode used, size they occupy in memory or by the functions they perform. Figure-1 shows the classification of the instructions
Figure-1: Classification of Instruction Set of 8085:
Instructions Based on Size :
These instructions can be classified are as follows:
One byte Instructions: These instructions are of one byte in size and hence occupy one memory location in RAM. Examples are CMA, RLC, RRC, RAL, RAR, STC, CMC etc. These instructions do not require any operand to be specified with the instructions, instead the operand is implied in the instructions.
Two Byte Instruction: These instructions of two byte(16-bits) in size and hence will occupy two memory locations in RAM. Examples of such instructions are MVI C,0A;
Three Byte Instructions: These are of three byte in size and hence occupy three locations in memory(RAM). Examples of such instructions are CALL, JMP etc.
Instructions Based on the functions: Based on the functions Instructions can be classified as :