I need at least one 341-0229-A PROM to convert one of my Lisas back to normal instead of the screen mod. But unfortunately VintageMicros has ended business, migrating the store and any remaining listings to a new owner, and those PROMs are not in stock. My simple XGecu T48 can't program these, and I need anything to replace this PROM as I can't find any others anywhere online. All I need is someone who has one pre-programmed, a way to program one for me, or a way that I can program one myself.
-
Hello Guest! We're hosting a challenge to welcome vintage Intel macs to the MLA during the month of July! See this thread for more information. -
We've made some quality of life improvements to the Trading Post. More info here.
Lisa Video ROM Help
- Thread starter mooplef
- Start date
I think I found a solution for under $500: https://eduardocasino.es/posts/TI-National-Bipolar-PROM-Programmer/
Is it a 256 x 8 bipolar PROM? Looks like there's this guy in NL if you just need a one-off: https://www.ebay.com/itm/225735683671
Yes, that will work, thank you!
Modern EEPROMs are too slow.
Although the replica Lisa I'm building is not finished, is has working video output.. And I deem for that a working Video PROM is needed? I'm using said adapter with an AT27C512R...
This is definitely incorrect....
From the datasheet that I found, enable access and enable recovery need to be at least 30ns, and I couldn't find anything that could match that, but I also don't exactly know the best places to look. Plus someone else much more knowledgeable about Lisas told me that as far as they knew it couldn't be done, but it seems like someone else was able to get it working. Still, buying 2 chips plus shipping for $50 which are exact drop-ins are much more manageable for me than designing my own conversion board and trying to get an EEPROM to work.
Keep in mind recovery/enable are *maximum* values, modern flash/eeprom will have much lower values (as they are faster to enable the drivers or change address) and that's fine. Fair enough though on re-engineering the board. You might check if there's an arcade repair place in your area - those folks deal with some real vintage stuff sometimes and they might have a programmer that could work.
