About this NTSC rev 3 board…. It was shelved appx 10 years ago patiently waiting a bit of troubleshooting. Long story short, I was using the rev 3 case (chicken lips) for my rev 6A board as the rev 6A machine had an unfortunate accident about 10 years ago. The rev 6A mobo, floppy drive, keyboard circuit board & bottom case is all that survived. When I was salvaging the 6A machine, I found that it would no longer boot. Swapped some CIAs around from the rev 3 board brought it back to life. Recently needing to verify bad CIAs now in the rev 3 board, I found it cheaper to just buy another rev 6A board. Determined bad CIA and ordered a couple (MOS for authenticity). Rev 3 board all better now.
So back when I bought two A500 machines around 2005 (can’t remember why I bought two - they were dirt cheap then) I had no idea that there were different motherboard revisions. Well, you know how it goes, the more you learn, a guy figures out what he has and after checking what rev the second machine was (after the transplant) I started modding the rev 6A machine just the way I wanted it. I just took my time over the years. So always remembering that the rev 3 board was shelved, I realized that I need to put that machine back to its formal glory. Why? Cause this stuff is getting harder and expensive to replace & I realize what these machines are worth now! Funny, when I bought them I kind of treated them crappily. The 6A machine was simply used as a toy when the guys would come over for beers in the garage (good times!). Now, I treat this stuff like gold! LOL
So now looking for some parts to house my rev 6A - highly modded - board. And I now have a spare rev 6A mobo too. But, just to get the NTSC rev 3 machine (with the original US layout keyboard) back together, at a minimum I’m gonna need a keyboard.
So, now that you mention the Gary chip on a rev 3 board (this is great info you’re providing BLTCON0) I knew I had to take a second look at it ‘cause when replacing the MOS CIAs I noticed that the Gary chip was the only one (besides the CPU) that was not a MOS chip and I wondered if it had been replaced by someone. It’s labeled CBM 5719 / TC17G008AP-0025 / Japan 8713EAI. So, is this the Toshiba made chip? Would you happen to have a part # for the MOS Gary chip? But other than this IC, yes, I want to keep this board as original as possible (gloating purposes, ya know?). I had two 512KB expansions and one wouldn’t work with the rev 3 board. I stashed a keyboard and that expansion board and can’t find them anywhere!
Oh, and how did I know about the 16 IC’s? Cause Jens said so…. LOL
https://icomp.de/shop-icomp/en/produkt-details/product/A512.html#filter=*OK, sorry so long, but that’s the story. Now that I have some time to actually get my A500’s sorted out, I’m having lot’s of fun! Got all kinds of new goodies to play with for the rev 6A machine!
