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.<\/p>\n
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. <\/p>\n
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.<\/p>\n
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.<\/p>\n
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.<\/p>\n
Now I’ve got to take some time to fix my son’s Srt101 camera, which was recently dropped or at least roughly handed.<\/p>\n","protected":false},"excerpt":{"rendered":"
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 … Continue reading