The HD404669 Series microcomputers incorporate a DTMF generation circuit, two comparators, and a serial interface on chip. They also provide input and output pins with large current handling capacities. Thus they are 4-bit single-chip microcomputers that are optimal for use in multifunction telephones, cordless telephones, and other communications equipment. HD404669 Series microcomputers have a 32.768 kHz sub-oscillator for realtime clock use, providing a time counting facility, and a variety of power supply modes to reduce current drain. The HD407A4669 is a ZTATTM microcomputer with on-chip PROM that drastically shortens development time and ensures a smooth transition from debugging to mass production. (The PROM programming specifications are the same as for the 27256 type.) ZTATTM: Zero Turn-Around Time ZTAT is a trademark of Hitachi, Ltd.