Archive for January 5th, 2020

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!

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