How many machine cycles do one byte instructions have?

Depending on the particular microprocessor, a machine cycle is the fetch or store of one (typically, one byte) native Word. In the 8085, this is a byte fetch or store, plus the overhead in decoding and processing the instruction. In this case, the first machine cycle is four clock cycles, or T states, and subsequent machine cycles are three clock cycles, although certain instruction sequences, such as DAD, require two extra clock cycles.