[RetroTechie]

Hehe.. remembered an optimum wavelength ~255nm (and indeed - Wikipedia says 253.7nm. Close enough :).

> sunlight would erase a chip in weeks

Been there, done that. When I wasn't in a hurry, I'd stick some EPROMs in a foam & put 'em under a window. Usually took a bit under 3 weeks. But no point trying in the midst of winter; probably works but could take months.

Loved those windowed ceramic packages. Especially microcontroller parts like (iirc) 87C52. Lovely patterns to have a look at with magnifier.

[K0balt]

When I was a kid I used to spend hours exploring the surface of windowed ICs with my field microscope. I have a weird association of microchip architecture and the depictions of the surface of the “Death Star” in Star Wars. I think I used to imagine I was flying over the surface of the chip lol. I was slightly saddened by the electron microscopy of smaller node sizes as time went on, the features became more globby and a little less beautiful.