Programmable memory guide

Posted on Thursday, September 16th, 2010 in Chips, help by Ian

EPROMs are old-school data storage chips with a little window that exposes the silicon inside. Once these chips are programmed, they can only be erased by shining ultraviolet light through the window.

The EPROM help page is a guide to identifying and working with these devices. It also covers more modern programmable memory like EEPROM, flash, NVRAM, and PROM.

Image: Poil (CC-BY-SA)

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3 Responses to “Programmable memory guide”

  1. Chuck Bennett says:

    Since you picked the 1702 for the graphic, I thought I’d share a little known thing about it. When you erase most eproms they go to FF and the the process of programming discharges the bits that you want to be ‘0’ The 1702 worked backwards. Erasing it set the internal bits to 0 then programming it consisted of charging the bits you wanted to be 1. I know this from the first company I worked at as a programmer. The processor we used was the 8008 and the eprom was 1720s. We used KSR33 teletypes with the paper tape punch to produce something that the prolog m900 programmer could read.

    Sadly, i’m that old.. :-) google Pro-Log M900 EPROM Programmer and here is the 8008 board

  2. Chuck Bennett says:

    typo. 1702’s that is.

  3. Ian says:

    Thanks for the history! The default 0 state is really interesting. That programmer is really massive.

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