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Improvising an EPROM programmer

For a project (revitalizing a large 80’s liquid crystal display) I needed to program an EPROM. The EPROm should contain a character font that goes into the LCD so it can show characters. The EPROM required was a 2764, this is a 64 kilobit (8kiB) eraseable programmable read only memory, which is eraseable by ultraviolet light.

The first problem: I didn’t have a 2764. I did have a 2716 (16 kilobit), new old stock. I bought this in 1981 or so for the Elektuur Junior computer. I remember the Junior required a 2708, but by that time the 2708 was already obsolete and the 2716 was more or less pin compatible. In 1981 I changed a few pcb traces on the Junior and it worked as a treat. I imagined I could do something similar with the 2716/2764, although my EPROM has 4 times less memory than required, but it could still contain 1 ASCII character set.

But then my friendly colleague Bart came in and said: are you looking for this? And he handed me a second-hand 2764. Bravo. problem solved.

The second problem: the 2764 was not empty and needed to be UV erased. On the attic I found a 300 watt Philips Ultraviolet tanning lamp, that my mother gave to me thirty years ago. I used it back in the day to develop the photosensitive layer of pcb’s. I assumed it would be good for erasing EPROMs as well. Well, no.”

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