Microprocessor Instructions:

In the CPU we shall be using, there are 4 different kind of instructions and numerous variations of each, resulting in over 100 different instructions. These 4 types are following

1. ARITHMETIC,

2. LOGICAL,

3. BRANCHING, and

4. DATA TRANSFER.

ARITHMETIC

Usually the arithmetic instructions include subtraction, addition, multiplication, division incrementing, and decrementing although division and multiplication were not available in most early CPUs. There are two flags utilized with arithmetic that tell the program what was the outcome of an instruction. One is the Carry (C) flag. The other is the Zero (Z) flag. The C flag shall be described in the following instance of addition. The Z flag, if set, says that the result of the instruction left a value of 0 in the accumulator.