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   Tube❄️Time (tubetime@mastodon.social)'s status on Friday, 02-May-2025 15:45:20 JST Tube❄️Time

   i built a 1702A EPROM programmer! this design is from https://www.mattmillman.com/projects/hveprom-project/a-compact-programmer-for-1702a-eproms/

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     Tube❄️Time (tubetime@mastodon.social)'s status on Friday, 02-May-2025 15:45:19 JST Tube❄️Time

     in reply to

     here's the structure. the top half of the image is the address decoder and the bottom half is the array of EPROM cells.

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     Tube❄️Time (tubetime@mastodon.social)'s status on Friday, 02-May-2025 15:45:19 JST Tube❄️Time

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     here are four EPROM cells. the critical element is a transistor (circled) that has a floating gate -- a control electrode with no external connection! modern flash memories also use floating gates, but the construction is quite different.

     ✧✦Catherine✦✧ repeated this.
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     Tube❄️Time (tubetime@mastodon.social)'s status on Friday, 02-May-2025 15:45:19 JST Tube❄️Time

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     the first EPROM devices were intended to be erased using X-rays, but ultraviolet light turned out to be a more practical method (X-rays can damage chips).

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     Tube❄️Time (tubetime@mastodon.social)'s status on Friday, 02-May-2025 15:45:20 JST Tube❄️Time

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     astute viewers may note that this is a legit 🧐 3M Textool socket. it cost me $25.62, or approximately 10x what a cheap clone socket costs.

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     Tube❄️Time (tubetime@mastodon.social)'s status on Friday, 02-May-2025 15:45:20 JST Tube❄️Time

     in reply to

     the 1702A is quite old as you can see by the copyright on the die. (the 1602A is the non-windowed version of the part, which is identical except for the package)