As of this morning, the flakey video problem wasn’t completely solved. The current counter parts I’m using are 74161A parts, and I was hoping I would manage to find some without the A suffix locally, as they have slightly different specs. I stopped on the way home hoping to find some 74161’s at the only shop in the area likely to have such parts. I lucked out and we found enough parts in a close out bin.

After I got home, Mike Fortuna (who works nearby) dropped by with a couple of cards to try on the Mimeo 1. First we tried out Rich Dreher’s CFFA 1 card. Not only did it work, we were able to load and briefly run a couple of classic programs. These included Apple 1 BASIC, Lunar Lander, and chess. I was impressed with this card.

Second, we tried Vince Briel’s prototype cassette interface card, but we had less luck with that one. The behavior was similar to the Obtronix cassette card that I built up. Write appeared fine, but reading was unreliable. I’ve still more work to do on the cassette interface front. Mike says the card works with his replica-1, though I don’t think that Vince was ever able to get it to work.

Mike and I also discussed the video problem, and we agreed that the symptoms are that of a video counter issue. It was great that Mike could stop by and help me check out the board and talk vintage computers.

After Mike left, I swapped out the 74161As with the newly purchased 74161s and after an hour of testing, things are looking promising. It is starting to look like I might have to ask my supplier to do an exchange.

Now I’ve got to take some time to fix my son’s Srt101 camera, which was recently dropped or at least roughly handed.