Unidentified chip

On 08/04/2015 1:48 PM, dwight wrote: It might be possible to identify it a bit. Using the Diode Test of your basic multi-meter you can probably figure out if there is a ground and Vcc pins by comparing the likely candidates (pin 8 for gnd, and 16 for Vcc) against other TTL based ICs. If they don't match then chack against pins 5 and 12 which are alternate G & Vcc pins on some TTL. If no joy matching to TTL, then make a log of the various pin voltages relative to other pins and see if there is a pattern that emerges. Compare to CMOS next, then drag out a 16 pin OP-Amp based IC and see if it shows anything similar. I find that inputs and outputs on TTL do show a difference in voltage drops relative to Vcc and G, and also which way you use the probes. I did a small write-up years ago as a starting point: http://www.flippers.com/service.html#diode John :-#)# -- John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames) www.flippers.com "Old pinballers never die, they just flip out"