OmniMac Ultra keyboard woes

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16 Feb 2021, 01:59

Yes, I'm one of the few folks with an Omni Mac. (Not my keyboard, but I'll be talking about odd key layout stuff, and those are better pics than I can take.) Yay, me. I've had it for a while and I swapped out the rather average white Alps in it with some very nice ones. So, after I did that, I used a keyboard tester to make sure all the keys work. It can click when a key is pressed, so it makes my life easier.

Test 1: ADB Cable to Drakware Converter
On Windows, I had problems with three keys: Caps Lock, Num Lock, and Scroll Lock. CL and NL seem to click two to five times. SL clicks a bazillion times and doesn't stop until I unplug the converter.

On Mac, no problem with Caps Lock. You don't use Num Lock on a Mac, so no problem there. The Scroll Lock button is F14, which decreases the backlight. I press the button. Turns the backlight to zero. So, something's not right.

Test 2: PS/2 Cable
I set the appropriate DIP switches and hooked up the OmniMac directly to my Windows 10 box via PS/2 (only adapter is a 5 pin DIN to PS/2). Caps Lock, no problems at all. Only one click. Num Lock. Also no problem. Scroll Lock ... well, if you set the Omni to use AT protocol, the F13 (Print Screen), F14 (Scroll Lock), and F15 (Pause) keys are disabled. They don't even register a code. However, those keys' functions get shifted down a row, so F13 is now the accent/tilde key, F14 is now the back slash/pipe key, and F15 is now the comma/period lock key. And Scroll Lock (now the back slash key) works just fine. However, the print screen key (now the accent/tilde) works one out of three or so presses. I replaced the key switch with known good. Still a problem. Heck, I even tried a Matias switch and it's still a problem. I can't find any continuity problems with my multimeter, either. This key was a problem before replacing the other switches, so the problem isn't caused by my awesome soldering skillz or anything.

So, anyone got any ideas? I had some thoughts about the Delay Rate / Validation Time settings, but that requires a RATE SELECT key, which is missing from the OmniMac Ultra. And, as far as I've been able to determine, there is no manual for the OmniMac online.

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16 Feb 2021, 03:10

A few random thoughts.

First, as far as I know it's never been confirmed that an OmniMac uses the same controller/ROM as the PC version of the Ultra. Decades ago I was told you had to change a crystal to make one into the other, but that's since been proven false. But there may still be internal hardware differences. The fact that most keys work correctly on yours between Mac and PC suggests the controller/ROM is the same at least.

One possibility is that you don't have the dipswitches set correctly. Those settings are definitely different between Mac and PC. There are at least three versions of the Gen2 Northgate User's Guide posted online, and some of the dipswitch functions are different between the three versions. The latest version for the Gen2 is the same as or similar to the Gen3 Northgates, but the OmniMacs are probably earlier than that. The Northgate manuals I've seen don't even mention the Mac version, but for the Mac try 1 and 3 down, or 1, 3, and 8 down.

Previously on this forum someone posted a bare PC board photo of a Gen3 Northgate. As far as I can tell all the Gen3 models used the same PC board, even the 101 (which was done by breaking off the left edge where the function keys would go on the other models). Looking at that photo (attached) you'll see that many of the switch positions, including the three you're having trouble with, had two possible orientations of the actual switches, giving two possible functions for each position depending on which way the switches are installed. The legends on the PC board are clearly labelled with the two functions. I don't have a Gen2 handy at the moment, but it's possible those worked the same way, and that those switches would need to be flipped around depending on if you had a Mac or PC model. So there may indeed be more to converting a Northgate from Mac to PC than flipping dipswitches (which would explain why they were sold for one or the other and didn't share manuals).

Does anyone here have a user's manual for the OmniMac?
NorthgatePCB.jpg (621.79 KiB) Viewed 520 times

User avatar

16 Feb 2021, 22:18

> The Northgate manuals I've seen don't even mention the Mac version, but for the Mac try 1 and 3 down, or 1, 3, and 8 down.
I'm the one that posted the info about 1, 3, 8 :D. I'll give just 1 and 3 a shot, though.

I think you've got the wrong pic. It's got a connector for an attached cable (to the left of the GND marking). I haven't read through all your OmniKey stuff (context: Polecat has a bunch of OmniKey info and I'm slowly trying to get that into the wiki), but attached cable is only for the gold-label 102 and the 101s, right?

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17 Feb 2021, 02:23

That photo is of a Gen3 PC board, which had a short jumper from the PC board to the rear panel PS/2 connector. (not an attached cable, but the same sort of connection on the PC board) Those are different than the Gen2, which had a separate controller board with the PS/2 (and ADB) connectors directly mounted, but I posted that as an example of how Northgate provided for two functions on some keyswitches by having two sets of pads for flipping the switches around the "other" way, which *might* also apply to the Gen2 OmniMacs. Just throwing out ideas somewhere between waking up and my first gulp of coffee (which often makes things even worse...) and running off to work. I can open up my OmniMac later this evening to see if it's made the same way.

edit - my OmniMac (Gen2) does not have the double sets of pads as in the Gen3 photo, so that idea can be tossed out.

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19 Feb 2021, 00:03

The continuation.

At this very moment, I'm typing on the OmniMac with the Drakware converter on my Windows box. Dip switches are 1 and 3.

* I did some testing with both the keyboard tester website I mentioned and SharpKeys. It looks like whenever MOST function keys are pressed (including Print Screen, Scroll Lock, Pause, which are F13 to F15) a shift or other key is also pressed very briefly.
* I'm getting a lot of key chatter on random keys with this dip switch combo. I don't know why.
* I remapped the lock keys with SharpKeys to F5 - F7. These were the exceptions to my function key problem I mention above. They turn on the lock keys without a problem, which implies something physically wrong with the actual lock keys or connection between them or something like that.

I'll have to play with more settings. It's also possible that my Drakware converter isn't converting. I did try two and two different USB and ADB cables.

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19 Feb 2021, 06:11

On at least one version of the Gen2 Northgates dipswitch #8 is for "sticky keys" (holds the modifiers on until you press them again, for people with disabilities), so that could have caused at least part of the problem(s).

Is the key chatter always on the same keys, or does it move around? Sometimes Alps switches do that after not being used for a long time, and it often clears up after you start using them again.

I'm still thinking there might be a difference in the controller ROM on the OmniMac versus the PC versions, causing the F13-F15/PrtScreen-ScrollLock-Pause keys to behave differently on Mac and PC. In other words you couldn't just swap between Mac and PC by flipping dipswitches. I really need to dig out my old Mac IIsi and play with my Gen2 Northgate models on ADB to see what happens. If only my boss would be as understanding about these things, but he actually expects me to show up and earn my paycheck!

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20 Feb 2021, 18:20

> On at least one version of the Gen2 Northgates dipswitch #8 is for "sticky keys"
Gotcha. That's good to know.

> Is the key chatter always on the same keys, or does it move around?
Moves around. It's gotten a bit more stable, so maybe doing another week-ish of typing did help. Either that or I'm just typing better on it.

Here's a related, possibly interesting, thing: I now have an OmniKey 102 (Vendor Code 777). The PCB has filled-in (with solder) sockets for all the key switches you'd find on an Ultra and it also has spaces for these switches in the metal mounting plate. PCB says "OmniKey Ultra/Plus/102." Makes me wonder if I can throw some extra switches in there and see if it works. I could swap the top bezel from the OmniMac ...

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20 Feb 2021, 20:41

The other versions of the Gen2 User's Guide have different functions for some of the dipswitches, which is one of the things I'm hoping to understand and document eventually.

In the "Rev A 7/90" book switches 7 and 8 were used to select normal or Dvorak layouts. 7-8 up was normal, 7 down 8 up was Dvorak1, 7 and 8 down was Dvorak2.

In the "Omnikey Plus User's Guide" (no version or date, but I believe it's for an early Gen2 Plus model, probably the Vendor 222 version) dipswitches 7 and 8 were used to program the top row function keys (later Plus models had only the left side F-keys, and the Ultra had the top row ones) - 7 and 8 up - standard, 7 down 8 up - shift-Fx, 7-8 down - ctrl-Fx, 7 up 8 down - alt-Fx. * see edit below.

We all want this stuff to be simple, but sometimes it just doesn't work that way. Northgate built a lot of these keyboards (one article says 250,000 in one year!) and a lot of changes were made.

It certainly won't hurt anything to try installing the extra switches on your 102. We talked about that here a while back, but I don't remember results ever being posted. I'd try just one first, just to save time in case it doesn't work. Some Gen2 Northgates had a separate EPROM on the controller board, while others had the ROM inside the controller. There was a jumper for that on the PC board. To complicate things even further, there were different firmware versions for the separate EPROM, and probably of the onboard ROM also, which was almost certainly related to the dipswitch settings. The version number on the label on the bottom of the keyboard sometimes did not match the version number on the EPROM, so I don't think we can go by the version number on the label. Combine that with the multiple vendor numbers and models it makes for a LOT of different combinations for the Gen2 Northgates. I'm working on all of this, as time permits, but I'll probably have to find examples of some of the different versions in order to answer some of these questions.

* edit - in reading the early Plus book more closely, the second set of function keys across the top was *optional*. This confirms ny guess that this was for the early version of the Plus, before the Ultra model came out- Ultra apparently became the new model name for the version with the extra F keys.

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21 Feb 2021, 02:03

> in reading the early Plus book more closely, the second set of function keys across the top was *optional*
Seems that way. I think if the OmniMac is set up to do Mac -- using the Drakware, 1 & 3 DIP -- and connected to a PC, both the side SF and top F keys are the same, e.g. SF10 puts out the same key code as F10. I think.

The 102 I have is in a bit worse shape than I thought. The key mounting plate was badly rusted. I Evaporusted it and sanded it down.
I'm going through my layers of Rust-Oleum paint + primer, right now. I can see that one of the diode leads rusted through and several of the other wires on the PCB have some level of grunge or rust. I've also got a small crack in the top case (plastic) and one of the case screw mounts was snapped off (seller sent me the part, at least). I'm also going to probably ultrasonic the entire switches, as most of the bottom casings have rust smeared on them. There were also some stickers applied to the case, so an extra level of cleaning on that is also needed. The switches do feel pretty good, though!

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21 Feb 2021, 02:55

On the Gen2 Northgate Ultras (the PC versions) the top SF keys were defined using the SF select key (press and hold), then pressing and releasing the desired modifier (shift=default, control, or alt). Pressing esc makes them unmodified F-keys, same as the left side ones. This only works on Ultras with the SF Select key, of course, and I suspect it isn't saved, so would have to be repeated for each session. My OmniMac Ultra does not have an SF Select key, so you're probably right about this not being an option on the Mac versions. (and one more reason the Mac and PC Ultras were not the same).

For what it's worth I've had good luck using ABS plumbing cement to repair broken screw mounts on the cases. The only hard part is having the patience to let them cure for a few days before reassembling. For screw mounts that were split I made some sleeves to go around them using pieces cut from an old TV rabbit ears antenna. Those, combined with the plumbing cement, made for a solid repair

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21 Feb 2021, 05:07

Going back to an earlier reply, I just found this photo (from Sandy's page) of a late (rev 6.04 Vendor 777) Gen2 Ultra and it indeed has the dual sets of pads (as on the Gen3 models) for many of the switches in the nav area. Glad I wasn't imagining what I thought I remembered.

Eventually we'll have a list of all these differences, and perhaps then we'll be able to meaningfully understand and document these keyboards!
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