Recent content by Oswald

Yes, it works with my PET SD card readers. There are a few spots on the case with chipped/scraped/rusted off paint I’d like to do something about. I am extremely hesitant about using paint on the case, although I would NOT be painting the entire thing, just the affected spots. I may end up not...

Both cassette ports work, and I’ve even managed to get the built-in port working semi-reliably. So for right now everything seems good!

So with the new RAM chip installed I get no errors in the DRAM test (let it run 200 times). The issue with the keyboard had already seemingly disappeared before replacing the bad RAM chip so I don't think this has fixed it, and I suspect it'll crop up again in the future.

Actually it's changed since I posted that address earlier in the thread, now it's 0 0 1C00 01 01. But I did swap some of the RAM chips around so that's probably to be expected.

0 0 1C00 10 10

Yes, seems so. I've already ordered some replacement RAM.

Hi Hutch, the ROM checksums stay the same. Each key flipped only a single bit except space and return, but I assume that's because those are actually two separate keys under a single key cover? The keyboard issue I described earlier in the thread only appears sporadically now, for some reason...

This is what I see when I run the test. The DRAM test correctly reports 8k.

Aha! I set the write offset to $F800 and it worked! I'm getting a mem fail at 0 0 1C00 10 10.

IMG_5503.jpeg - nothing in H3 IMG_5505.jpeg - EPROM + RETRO adapter in H3 The one I linked earlier in the thread: Major Brands 27C512-15 EPROM, 28 Pin, DIP 150 Nanoseconds, 64k x 8, 5Vs. There are some labeled solder pads on the adapter, I’ll check if these are the pins you mentioned when I...

Unfortunately I'm only getting garbage on the screen. It looks the same as with nothing in the socket at all. Maybe I'm burning the EPROM wrong? These are the settings I'm using:

So the 6540 RAM adaptor has finally arrived. I think I've successfully flashed an EPROM with Dave's PETTESTE2K v4 but just want to verify it goes in H3 on the board (apparently corresponding to E000-E7FF, if I'm understanding this page correctly). Additionally, do I need to modify the source...

I ended up removing the resistor entirely and that fixed it. It wasn't present in the original CB2 audio schematics from the 70s, which makes me wonder why it was added.

Replaced R3 in Matthew D’Asaro's PET video mixer schematic with a 210 ohm resistor, but I later realized the problem was happening because I was injecting 9v instead of 5v... oops! I also added an LM386, speaker and line out for audio, sounds great! Now if I can just get this tape drive working...

Update on the cassette situation: I've been able to get the PET drive to save cassettes fairly reliably (though still with occasional errors/corruption) but haven't once gotten it to load. I've cleaned the heads, fiddled with the capstan roller, changed the belt, and still no luck. Any ideas...