TheAPU4006 i s a single-chip 4-bit microcontroller with LCD driv ers. It can driv e up to 3 common time 20 segments, i.e. 60 segments LCD driv er. This 4-bit microcontroller contains a 4-bit parallel processing ALU, 1024 x 15-bit program ROM, 48 x 4-bit data RAM, input ports, alarm driv er, timer, clock generator, crystal and RC oscillator circuit, LCD driv er and 70 powerf ul instructions in a single chip. It uses HALT instruction to stop all internal operations other than the timer, clock generator, crystal/RC oscillator and LCD driv er. Very low current dissipation can be easily achiev ed by combining 4 types of interrupt f unction and HALT instruction to minimize the operation cycle.