The Kaypro restoration is coming along, but not a lot of headway has been made. I’ve manage to convert the board back the way it was when it left the factor, as can be seen in the picture below. However, there is at least one problem with this. U87 was factory suggested modification, and I have learned both from a reader on this blog as well as a guy on Facebook that it was a service repair of some sorts. Something about corrupted data. So that repair will be redone. I guess it is for the best, seeing as how the previous sockets were worn from the constant pressure of the machine pins over the course of the last 30 years. Rather that just sacrifice the chip, the person who did the original repairs sacrificed both a chip and a socket. And the sockets caused the factory placed sockets extra wear. In other words, it needed to be replaced.
The next step was to take a look at the CPU’s activity, and see how everything was going. And It appears that the CPU is hopping along quite normally. However, I did notice that the clock appears to not quite be 2.5mhz. Rather, it appears to be a stable 2.4mhz. The picture below shows (from top to bottom) the clock signal, the MREQ signal, and the IORQ signal.
All and all, it appears that the machine is running, executing code, and generally performing routine memory operations as well as I/O operations.
As for the video problem. Well, the good news is that there is at least some type of video signal. But I’m not sure if it is garbage or actually has something to it. The pictures below shows (from top to bottom) the Vertical Sync, the Video signal, and the Horizontal Sync.
I’d love to know if anyone knows if this looks pretty standard. Or if there appears to be something amiss with these video signals. Because, like I have mentioned in the past, I have no knowledge of video signals or CRT displays.
However, I have see mention before of a pretty easy circuit to fabricate that combines the vertical, horizontal and video signals into a single composite video signal (this was for the Commodore PET). And I may end up sitting down at the bench one day in the next week or so and solder this up. However, I find it hard to justify using the time for that. Since I do have my G-80S prototype video board under construction at the moment (another project involving video signals which I have no understanding of). However, I’ve attached the following picture of a schematic I have found for the mod. It seems interesting enough.
I have no idea if it’ll work. But I cannot imagine that the signals are that different. But who knows, like I said, I know nothing about CRTs or video signals.
So, a little work has progressed, and will hopefully continue. Also, I’m still looking for a boot disk for the working Kaypro 2X. If anyone has the ability to make me one for a decent price I’d be a paying customer. Shoot me a email, and we can talk.