Hello,
I have two old ICs that I grabbed some months ago before they were thrown into a bin. They caught my eye as they're gold and white ceramic. I've attached a photo, but here's a textual description too:
The first is a 14-pin DIP chip, with a fully-gold upper and lower portion sandwiching white ceramic in the middle, with gold pins. The top is labelled "PLESSEY / MP131B / 51974", there is no marking on the bottom.
The second is a 24-pin DIP made of white ceramic, with a gold plate over the die area. There are two holes through the white ceramic, and a gold trace runs from the plate to the notch. The pins are again gold. The plate is labelled "GIM-0 / 16-M / D0876", the bottom of the chip is plain white ceramic.
The manufacturer for the first is quite obvious; as for the second my best guess is General Instrument's Microelectronics division. The labels look like they include date codes from the 1970s. I've searched numerous online datasheet websites using variations of the label texts, and also looked through several old component books from the 1970s on archive.org, but to absolutely no avail. I can't find any evidence that Plessey had a line of ICs that were named MPxxx, and the other part's label is less that helpful. "16-M" made me think of ROM or RAM, which would fit with the 24-pin DIP shape, but that would be way too large for 1976: 1977 saw the commercial release of 16Kilobit EPROMs.
I don't know if these are functioning or not, I haven't applied any voltages to them as I don't know their pinouts, and want to avoid frying a potentially working chip by shoving the wrong polarity down its throat.
I realise the odds of somebody recognising either of these on sight are very long, but I'd also be receptive to any suggestions on what further investigation I could do to try and work out what they are.
Thanks.