levoman wrote: ↑Sun Jun 14, 2020 12:04 pm
I will have to get hold of him. Just wanted to include it as it is the one that started the thread.
The point of the thread is that in 2008, I discovered the M27C512-90B6 as one of the very few (E)PROMs which could safely be used that could be used as PLA and a group of people did everything they could on Lemon64 to discredit this working solution and they even managed to get me banned from that forum.
In 2011, this '1$ PLA solution', which incidentally can also work with the C16 and Plus/4 if programmed accordingly, was discontinued by ST.
Bad mouths deprived the Commodore community of a perfectly reliable and incredibly inexpensive solution to a nagging problem of Commodore 8 bit computers. They even punished me for persisting in telling the truth.
Now, the M27C512-90B6 is certainly not unique and the Super Zaxxon cart as well as the 74LS279 test circuits are methods for finding other memory chips (PROMs, EPROMs, Flash, etc...) which can act as reliable PLAs. Apparently, there is this 'Axel81' guy on Amibay who found a trustworthy alternative but he won't say exactly what the chip is. He grinds the surface before selling.
Presently, if I disregard the zoo of antiquated, fakes and dirt cheap junk EPROMs offered on eBay and limit myself to reputable distributors such as Mouser, Avnet and Digikey, there is a good list of 64k x 8 non-volatile memory ICs that will operate at 5V.
These include a bunch of different speeds and package AT27C512R from Microchip, the AT27LV512A also from Microchip and the AT49F512 Flash ROM. I don't have time to test them but maybe you guys do.
Be normal.