Working on a mid-80's engine control unit, I have spent the better part of two days finding datasheets/pinouts for two mystery chips. I originally thought they were 4000 series logic chips, but no such numbers exist.
The unit is from a gen and appears to be a Ford EEC-IV controlling throttle body injection, on an accessory board labeled "FBC", for "Feedback Carburetor"
The were apparently made by Signetics (now NXP) – due to the S on the chip.
However, I cannot find any datasheet for either the 4501 or 4514 part:
The full markings are:
IC1: 4501 8408 S 005BB
IC3: 700002BB 8422 S 4514
I was able to determine that:
IC1 has +5V on Pin 3 & GND on pin 12
IC3 has +5V on Pin 4 & GND on pin 8
I suspect that 8408 / 8422 are date codes. IC3 smells like some sort of OpAmp with nonstandard pinout!?
For what it's worth, here are schematics I drew of the periphery around them:
Any hints, however silly, are appreciated!
UPDATE After getting my hands on some high resolution images of other boards, some of them have:
IC3 = S4501 = S4017 = RCA 340; but they are all marked (70)005BB
IC1 = S4514 = S4513 = S3501; but they are all marked 700002BB
It appears that this is the "true" model number of an ASIC possibly. I have not found any cross mappings of internal part numbers to real part numbers as for the other board yet.
Best Answer
I believe to have identified the chips by elimination based to supply voltages, VCC and GND pins.
IC1 = LM339 or pin-compatible
IC3 = TI5534 or pin-compatbile
I have redrawn and simplified the schematics while hopefully making no mistakes and the circuits seem to become more understandable and sensible:
For now, I won't accept it as answer, but wanted to provide it as potential answer. Should anything change about my assumptions, I will update the post.