Recent content by chapmro

That is a good suggestion, that the problem may lie in the top connectors themselves. A lot of this machines troubles have been fixed by applying Deoxit to connectors. Maybe this one also, but if not I will certainly start with MAC on E17.

So today I tried a TAD instruction at address 1, and it worked. In fact I could execute it over and over and watch the AC go up by the amount in the memory address. But this tells me a good bit, in particular that all the adders are working, and the CPMA itself is working, and that the...

I am trying to get a pdp-8/e working. I have replaced the core memory with a single, new semiconductor memory board (http://tronola.com/html/ram_for_pdp-8e.html). I can load an address, deposit something in it, examine it, but the address does not increment when I use the deposit or examine...

It is non-gate array, and I've convinced myself the motherboard is fine by borrowing a "top half" (crt and video board) from another computer, and the video output looks fine. My original problem with this machine is that the video board blows fuses. Nothing is obviously damaged on the video...

I am trying to repair a model 4 with a dark screen. I posted earlier about the video board, but in absence of a way to debug that, I thought I'd work backwards. I looked on the scope at the 3 outputs from the main board to the video board. The H sync and V sync pulses are there, but I am not...

To use the M3 video board with an M4, looking through the model IIII/4 tech ref manual, it looks like the yoke wires are in two pairs, one for vertical, one for horizontal. I can check for which two wires make up each pair with the continuity tester on the multimeter. It looks to me like I...

I was given a Model 4 which keeps blowing the video board fuse. I was told that something "shorted" in the power supply (who knows?). The power supply fuse does not blow, and if you disconnect the PS and give it AC, the output voltages look ok. If you hook up everything except the connector to...

fabriciotm, did you ever find a working hard disk image to test? I am also searching for the same. My present plan if I cannot get an image is to attempt to recompile the VHDUTL program for Kaypro from Vercoven's source file using ZMAC, then use that to make a blank 1024-byte sector image.