name: HT93215B function: 1-Memory Tone/Pulse Dialer package: DIP18,18 manufacturer: Holtek +--()--+ HFO | 1 18| HFIB HKSB | 2 17| R4B MODE | 3 16| R3B X1 | 4 15| R2B X2 | 5 14| R1B VSS | 6 13| C3B VDD | 7 12| C2B DTMF | 8 11| C1B XMUTEB | 9 10| POB +------+ This pinout came from the Chipdir: http://www.chipdir.org/