Recent content by Ttpilot

I think that'll have to be put off a while. I also have a North Star MDS controller. When I put it in I experienced some of the same problems. I also noticed that my CPU card would no longer run a PROM mounted on it. I installed a couple of different monitor PROMs on it with no luck. I'll start...

I forgot to mention the disks are 10 hard sectors

I put the North Star fdc back in and booted into NSDOS to use the monitor. I used that to run memory tests most of yesterday. No errors. I also loaded a huge chunk of RAM with 11s and let it sit overnight. I scanned through and no changes. I guess RAM's not an issue, at least not on the RAM17...

I checked all the 74LS chips. They were okay, but I found a 74LS221 in a 74LS123 socket. I switched in a 123. I set all the cpu switches, set the ram board to 64k and risked it. The thing worked! I was able to boot, see disk contents, run some programs: Eventually, this happened: It‘s...

Interesting. Mine is serial no. 10-02778. I have a round hole for the fan That's not the original fan, though. I replaced the power supply earlier this year with a switching supply. The old supply was dimming the lights in the neighborhood when I turned it on ;-). Makes the case about 25 lbs...

My cover is from the machine I built in 1978. This is the nameplate for that model: The model in the 1980 catalog has a different logo on the nameplate:

One last thing, here's the front mounting hole with a scale for more accuracy

The cover is stained, but I don't think any other finish was applied. It's quite dull in appearance

Forgot the top view, just to be thorough

Here is the information on my cover: Exterior Front to back: 17-3/8” Side to side: 20-1/2” Top to bottom: 7-1/2” Wood thickness: 3/4” Front mounting hole: 1-9/32” from front edge to center 1-1/2” from bottom edge to center Rear mounting hole: 1-7/16” from...

I was able to read the bipolar ROMS on the DJDMA board (actually, both boards) following a method outlined by Damian MacMillan. When I compared them to the ROM dumps I found online I get the following results: 6301 ROM at 12B on the boards: The chips on the board seem to match the ROM dump 6305...

I found the PAL and PROM contents on archive.org. The 9401 turns out to be a CRC chip, so it's probably okay. The 6301 and 6305 are bipolar ROMS. The PAL16R4 I think I can replace with a GAL16V8 and can program with my TL866 II Plus. Now I'm on the hunt for someone who has some of those chips...

Now that the North Star Horizon motherboard and power are sorted, along with the Compupro CPU-Z and RAM-17 boards, it's time to try to revive the DJ/DMA fdc. Actually, I have two of the boards, so I'm hoping I can get at least one working. I'm starting with the one that I bought off Ebay a year...

The CPU-Z board and motherboard are functioning correctly at last. I made a modification to the test program to put in a delay loop between setting up the 8251 uart and the rest of the routine. That fixed the problem with stray characters being printed on the screen. Thanks for your help on...

Good call on the x64 setting. Even the schematic says x16. I don’t know where I came up with that. Anyway, it seems to be working pretty well now, once I got the right mode setting for the 8251. I wrote a little app that prints out a title, then loops for input, which is echoed back. I’m not...