Scrap EEPROMs

A quartet of defunct 64 KB EEPROMs (*) emerged from a box of microscope doodads, so I stuck ’em under the stereo zoom scope for final pictures.

The oldest one, an MCM68764, came from Motorola with a 8313 date code. The next three, all TMS2764JL-25, came from TI with date codes in 84 and 85, so they have slightly different layouts.

MCM68764C EPROM
MCM68764C EPROM
TMS2764JL-25 A EPROM
TMS2764JL-25 A EPROM

This one is rotated 90° counterclockwise:

TMS2764JL-25 B EPROM
TMS2764JL-25 B EPROM
TMS2764JL-25 C EPROM
TMS2764JL-25 C EPROM

The hideous compression artifacts come from the original Pixel 3a images, because they’re (digitally) zoomed in all the way, plus bonus optical distortion from the quartz windows. The chips definitely look better in person, although the (optical) magnification isn’t nearly enough to show the tiniest details.

(*) Uh, they’re just EPROMs. It’s been so long since I’ve typed it that the extra “E” just stuttered right out. That’s my story and I’m sticking with it … at least I got the image names right!

6 thoughts on “Scrap EEPROMs

  1. Looking at IC’s with a fairly high magnification metalurgical microscope can be fascinating. One with the Nomarski bits can give some beautiful results. OTOH, it was part of the job in the day. I have a stereo scope (not zoom, but Good Enough selection of mag ratios), and that covers what I need.

  2. I still noodle around with EPROMs from time to time, including maintaining my collection of circa 1980 video arcade games. If “final pictures” means you’re discarding these, I’d gladly pay for the privilege of being your disposal …

    1. They had either “NG” or “NFG” (presumably for emphasis) scrawled on the ceramic, so I assume they ended up in the microscope show-n-tell box for well and good reason. Would that it ended differently!

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