Northgate OmniMac Ultra - w/DIP Switch Settings

hellothere · 17 Jan 2021, 17:53

New toy I bought from another forum member.

I was able to get the OmniMac up and walking on both my Mac and PC using an 5-pin DIN AT to PS/2 and PS/2 to USB adapter, but Caps Lock, Ctrl, Option/Alt, and Cmd/Windows key were all mapped wrong and the additional keys down the right side of the 'board (the section that has ~, \, comma lock, etc.) weren't working. I spent about an hour online and found the DIP switch settings for use with an ADB cable: one, three, and eight are down. The rest are up. Check the pic for the orientation I'm using. One is on the far left and eight is on the far right.

I don't have an ADB Mac, but the DIP switch settings work with my ADB to USB adapter. (The adapter I use is from drakware.com and currently costs $25. They often list the adapters on ebay with free shipping. YMMV with Hasu's TMK converter or other adapters. I don't see why they wouldn't, though.)

All the keys are now mapped as intended on both my Mac and Windows box and the cmd key does automagically map to the Windows key.

Note about the PS/2 cable, if you want to try it: the cable that came with the keyboard had a 5-Pin DIN to PS/2 adapter on one end. The adapter will not work if the adapter is plugged into the keyboard. You have to plug it into the computer. I haven't tried with a PS/2 male-to-male cable, yet. I do have a PS/2 port on my Windows box. I just don't have a cable.

Spoiler:

Polecat · 18 Jan 2021, 02:28

hellothere wrote: ↑
17 Jan 2021, 17:53
New toy I bought from another forum member.

I was able to get the OmniMac up and walking on both my Mac and PC using an 5-pin DIN AT to PS/2 and PS/2 to USB adapter, but Caps Lock, Ctrl, Option/Alt, and Cmd/Windows key were all mapped wrong and the additional keys down the right side of the 'board (the section that has ~, \, comma lock, etc.) weren't working. I spent about an hour online and found the DIP switch settings for use with an ADB cable: one, three, and eight are down. The rest are up. Check the pic for the orientation I'm using. One is on the far left and eight is on the far right.

I don't have an ADB Mac, but the DIP switch settings work with my ADB to USB adapter. (The adapter I use is from drakware.com and currently costs $25. They often list the adapters on ebay with free shipping. YMMV with Hasu's TMK converter or other adapters. I don't see why they wouldn't, though.)

All the keys are now mapped as intended on both my Mac and Windows box and the cmd key does automagically map to the Windows key.

Note about the PS/2 cable, if you want to try it: the cable that came with the keyboard had a 5-Pin DIN to PS/2 adapter on one end. The adapter will not work if the adapter is plugged into the keyboard. You have to plug it into the computer. I haven't tried with a PS/2 male-to-male cable, yet. I do have a PS/2 port on my Windows box. I just don't have a cable.

Good info, thanks, that adds a new piece or two to the Northgate knowledge base. I'm still trying to fill in all the blanks; every step gets us closer.

Far as I can tell the ADB (Mac) Northgates were limited to the Gen2 models. But not all of those had the ADB connectors. The Gen2s came with two different controller boards. Both versions had ADB provisions, but depending on model some had the ADB and supporting component locations left unpopulated. I'm still trying to determine which models, vendor numbers, and revision numbers were compatible with ADB. Dipswitch settings were also different between Gen2 Northgates. So far I've found three different lists of dipswitch settings just for the Gen2s.

Interesting that the cable/adapter combination would only work one way, since this is a passive connection. I'll have to try that with one of the factory Northgate cables.

hellothere · 19 Jan 2021, 00:59

M to M cable is on order!

I was reading up on ADB. The cable in the pic above is a standard S-video cable. ADB and S-Video are pin-compatible, but not 100% the same: the ADB cable had a connection for powering up the Mac and S-Video doesn't, nor does Hasu's TMK. Mac keyboards had a power button on them for quite a while, but not anymore. I might try a genuine Apple ADB cable and find out what happens. Maybe that button on the back of the keyboard will send a restart command or something.

Riverman · 21 Jan 2021, 01:51

ADB's power on signal just used one of the existing pins in an S-video cable. That pin and the wire are there in all S-video cables. I used to routinely use S-video cables to replace ADB cables and vice-versa back in the early to mid '90s, and they'd work fine. An S-video cable was fully compatible with the power on button on the old ADB keyboards. I always thought that was one of the coolest features of Macs, and I was disappointed when Apple dropped it when they switched to USB.