jrr at flippers.com
Tue Aug 4 16:29:31 CDT 2015
On 08/04/2015 1:48 PM, dwight wrote:
> This all assumes it is a TTL and not an ECL or even
> and analog chip, such as an opamp.
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:
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