Increment

The Increment microinstruction adds an integer constant to the contents of a register. The constant can be positive or negative. The constant is specified in the microinstruction, so if the user needs to increment by different values, then different increment microinstructions need to be used. If signed overflow occurs, that is, if the result is too big or too small to fit in the register using two's complement notation, then the overflow condition bit will be set to 1, if a condition bit is used. Otherwise the value of the overflow condition bit is left unchanged. In the case of overflow, the register will contain the rightmost n bits of the result in two's complement notation, where n is the width of the register.

Typical uses of the increment microinstruction include incrementing the program counter during the fetch sequence or incrementing or decrementing the stack top pointer during pushes and pops.

Parameters:

Register: the register whose contents are to be incremented.

Value: the integer value that will be added to the register contents.

OverflowBit: a condition bit. If not needed then "(none)" should be specified.