3+ Years Later....
CPU tested good. No power rail shorts. U7 (74S175) was the hottest thing on the board at 150F so I replaced it and found a bunch of sand like debris under it. Now the board works. I think that sand is probably under all the chips because I found it under the socketed...
I posted my homemade schematic of the GridCase Type 90h storage backplane (IDE + FDD) on the backplanes page. This was created by unsoldering all IC's from the board then mapping it all out with a multimeter. I then used this schematic to create a functional homemade backplane so there is at...
I found some more notes and schematics I drew up. I realize I've forgotten much of this stuff but I'm pretty good about keeping records... so I'll try to make it all accessible. For now though...
The 244 and 273 are for backplane identification.
If it has a GAL it's for decoding (such as for...
I'm not sure if this is any help or not but attached is a photo of an external 10MB hard drive that clamps to the top of my GRiDCase Plus and interfaces to the 50-pin connector. Inside is a PCB with an IDC header that appears to be an 8-bit ISA slot. There is an ISA card (Controller for the...
There seems to be an increased interest in the Grid stuff lately so I'm making an effort to post some of my findings.
I don't know if this info is out there already but yesterday I typed up the pinouts for the 1500 series mainboard backplane connectors. The expansion bay pinouts are there too...
I reversed this board a year or two ago and made my own that plugs in to my GRiDCase 1520 and performs the same functions as the original backplane but also gives an ISA slot. It was a proof of concepts so the computer couldn't be reassembled with an ISA card sticking up vertical but I've been...
I got these from C. Singleton a year or two ago and just noticed raw copies are floating around here. Optimized, OCR'd, and indexed versions are posted on my site if anyone wants. I have tons of other stuff I still need to process and a bunch more to scan for various GRiD models...
I've written a program 'RomBuilder Pro for GRiD' which has a modern interface and does a bunch of fancy junk. I think I'm in the final testing phase but haven't owned a Compass model in over two decades so I can't confirm results for that series. If anyone is willing to burn and test Compass...
I did a little more poking on this. Interestingly enough the VGA feature connector on this card has a jumper wire soldered to pin Z13, which should be unused/key so perhaps this is a slightly purposefully modified card. Unfortunately it disappears to an inner layer of the board so I haven't...
I have a gas-plasma panel being driven off the VESA feature connector of an Orchid Fahrenheit 1280 (1mb ISA card). The panel itself is capable of 16 shades but I am unhappy with the palette grayscaling when in display modes greater than 16 colors. It just goes psychedelic. For example, when I...