General Category > Lisa Troubleshooting and Repair
Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
blusnowkitty:
--- Quote from: AlexTheCat123 on June 01, 2021, 08:22:42 pm ---I just got the replacement 2732 I/O board EPROMs in the mail today, but my TL866II Plus programmer won't program the chips because they require a 21V Vpp when programming, but my programmer can only go up to 18V. The weird thing is that I've programmed 2716s that also require a 21V Vpp on this programmer in the past and it has worked fine, but now I'm stuck since I can't write to these EPROMs. Hopefully I can find a solution quickly and get the code into this chip!
--- End quote ---
I'll throw in my two cents here; since I do so much with all kinds of old computers I went and bought myself a Willem programmer. Fairly cheap, supports the really common 27-series EPROMs. Software can be annoying to set up, though, and you need a PC with a built-in parallel port. Probably doesn't hurt to wire up a 5 volt adapter as well, otherwise you'll be trying to step up 5v at 500ma from the USB port (power only) to at most 28 volts...
AlexTheCat123:
I found a strategy that, while incredibly inelegant, seems to be getting the EPROM to program. I just made a simple shell script that programs the EPROM over and over again and, after letting it run for a couple hours and then reading the contents of the chip, it seems to have successfully programmed around half the EPROM. Hopefully it will be completely programmed within a few more hours. I'm not sure how good these repeated writes are for the chip, but I bought 10 of them, so I'll still have 9 more if this somehow damages it.
patrick:
So you program 15 minutes at 18 V instead of 50 milliseconds at 21 V? Could work.
You will run into problems if you ever try to erase this chip again. But since your Lisa is supposed to last forever, this will never be necessary ;D
rayarachelian:
--- Quote from: patrick on June 02, 2021, 11:13:12 am ---But since your Lisa is supposed to last forever, this will never be necessary ;D
--- End quote ---
Heh, the only immortal Lisa is LisaEm ;) - and some day the only way to run it is running it inside an emulator. Yes, that may happen one day.
D.Finni:
--- Quote from: rayarachelian on June 02, 2021, 12:30:04 pm ---
--- Quote from: patrick on June 02, 2021, 11:13:12 am ---But since your Lisa is supposed to last forever, this will never be necessary ;D
--- End quote ---
Heh, the only immortal Lisa is LisaEm ;) - and some day the only way to run it is running it inside an emulator. Yes, that may happen one day.
--- End quote ---
Sure, but first you'll have to finish writing the emulator and fix all of its bugs. :P :P
*ducks and runs*
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