I built an EPROM programmer onto my original Explorer-85. I used a capacitor charge pump circuit with a 555 chip to make the 25V.
At the time I only had an analog voltmeter. And I can remember being very worried about the accuracy of that 25V,
being still a kid, and the datasheet putting a very tight tolerance on it.
Also the programming pulse time. 50ms, or whatever, I cannot remember now.
But it worked!
My college roommate had a summer intern job with Texas Instruments, in Texas, and came
back with oodles of 25xx series EPROMs (probably 2516) that were supposedly testing rejects.
My programmer was for those.
I had more trouble erasing the darn things, than programming them.
/Bill
At the time I only had an analog voltmeter. And I can remember being very worried about the accuracy of that 25V,
being still a kid, and the datasheet putting a very tight tolerance on it.
Also the programming pulse time. 50ms, or whatever, I cannot remember now.
But it worked!
My college roommate had a summer intern job with Texas Instruments, in Texas, and came
back with oodles of 25xx series EPROMs (probably 2516) that were supposedly testing rejects.
My programmer was for those.
I had more trouble erasing the darn things, than programming them.
/Bill