name: HT9312AT function: 12-Memory Tone/Pulse Dialer package: DIP20,20 manufacturer: Holtek +--()--+ TESTB | 1 20| KT C1B | 2 19| R4B C2B | 3 18| R3B C3B | 4 17| R2B C4B | 5 16| R1B C5B | 6 15| MODE X1 | 7 14| DTMF X2 | 8 13| POB XMUTEB | 9 12| HKSB VSS |10 11| VDD +------+ This pinout came from the Chipdir: http://www.chipdir.org/