Commodore PET ROM Programming

Pezdude

Active member
Hi all!

This may be a stupid question/issue on my part so apologies in advance! I think I am a bit lost in the process of programming EPROM/EEPROMs for use in my PET. I thought I got the right EPROM needed for my programmer, but it doesn't look like it is supported by the software I currently run to flash chips. Anyways, does anyone have any experience getting new ROMs setup for their machines? Or does anyone know good sites to look for EPROM/EEPROMs that may be more compatible with modern flashing solutions? I believe I am almost done getting my PET up and working (multiple ROMs were bad, so I ended up using a ROMulator.) Any help would be appreciated!

Thanks in advance!
 

Pezdude

Active member
Man I feel stupid 😅

I didn’t bother to check the pinouts on the PET character ROM IC and see if it was compatible with another EPROM. Turns out it is compatible with 2716 EPROMS! Still somewhat made today, so I just ordered a bunch off of eBay. Though they are coming all the way from China, so they won’t get here for a whole month or so. I may pay a bit extra for a local one just so I can (hopefully) get my PET up and running perfectly! I’m just crossing my fingers I don’t run into anymore issues with it, but I think a ROM replacement would be suspiciously too easy 🤣

I hope I can get the PET up and running by the time the next show is on.
 

Performa

Member
I just checked my stash, and I don't have any of those 2716 chips. Someone else around here might though. Good luck on the project!
 

PS2it

Well-known member
Hey thanks! Much appreciated 😁
I've got a 2564JL, I believe it should be pin compatible, or at least very close (I didn't compare the data sheets side by side). I've got some pin headers and sockets too, I'm sure we could make an adapter if need be.

If it'll work, you're more than welcome to have it!
 

Pezdude

Active member
Here is an updated on the PET situation! As of right now, my new EPROM came in, but unfortunately I received the same results. I read the original character ROM from the PET and it actually looked completely fine. Oh well, I have a spare for the future just in case! With this in mind, I de-soldered the socket for that ROM and will place in a new socket with fresh solder. I am now thinking it was a connection issue this whole time, which is very surprising to me considering how much trouble this computer has been given me haha! When I press down with a bit of pressure with the ROM in place, the lines go away and a the BASIC screen comes up. I am on the verge of success, but the fight is not over!

Oh and the keyboard no longer works, which I believe is a common issue based on the PET research I have done. Not sure if it is another connection issue or it really is the contact under the keys needing to be redone. Either way, more fun troubleshooting for the ongoing PET project!
 

Pezdude

Active member
I've got a 2564JL, I believe it should be pin compatible, or at least very close (I didn't compare the data sheets side by side). I've got some pin headers and sockets too, I'm sure we could make an adapter if need be.

If it'll work, you're more than welcome to have it!
Sorry for the late reply! Thank you so much for the offer! I actually got a replacement EPROM from a USA seller last week. It was another 2716 from Intel and it worked like a charm! Only issue is that the lines were still appearing haha! Seems to be a connection issue right now, but more troubleshooting awaits. Thanks again for the offer! Much appreciated!
 

PS2it

Well-known member
Sorry for the late reply! Thank you so much for the offer! I actually got a replacement EPROM from a USA seller last week. It was another 2716 from Intel and it worked like a charm! Only issue is that the lines were still appearing haha! Seems to be a connection issue right now, but more troubleshooting awaits. Thanks again for the offer! Much appreciated!
Glad to hear you found one! Can't wait to see it all setup and working!
 
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