Apple AEK II, strange behavior combi de and lkjn

rheinpfeil

18 Apr 2021, 11:53

Hi there,

As I can’t really make up my mind which keyboard I like best, I work alternately with three keyboards on my Mac:
- An IBM Model M (1391511, dutch) from 1992 with a Soarer PS / 2 → USB adapter
- an Apple Extended Keyboard II © 1989 model M3501 (dutch) with ADB → USB adapter from Tinkerboy
- a Logi Craft keyboard
For all keyboards I use a modified layout with Ukulele and Karabiner. This all works fine except for one thing. (By the way: the Dutch key-layout of an Apple keyboard is practically the same as that of a US key-layout.)

The Apple Extended Keyboard II has a problem with two specific key combinations:
- d e
- l k j n

d e
If the d or e is pressed, the other letter will not appear. So for example d pressed, no e. Or the e pressed no d. All other letters will appear. So the e pressed, and for example a w, r, s or whatever is no problem. The same goes for the d.


l k j n
With the l the problem is with three other letters.
  • If j, k or n is pressed, the l cannot appear.
  • When l is pressed, j, k and n cannot appear. All other letters can be typed. So the l and e.g. u p y t h is not a problem.
  • If the n is pressed and then the l sometimes a , (comma) appears
  • If the k is pressed and then the l sometimes a return is given.

This is a particular problem as I type at a reasonable speed. Sometimes one key is not completely released before the other key is pressed. This is no problem at all except for the aforementioned. As a result, a relatively large number of incorrect words appear. That has a delaying effect.

I’ve also performed the test under Windows with the same result.

Is this a known problem and if so what is a possible solution? Or is it ‘by design’ for these key-combinations? A test with an Apple Design Keyboard doesn’t show the same behavior. Thanks in advance for your ideas.

Rheinpfeil

User avatar
Muirium
µ

18 Apr 2021, 12:29

What you're suffering is a couple of artefacts called "blocking" and "ghosting", which are the symptoms of limited rollover. Feel free to read all about it; it gets complex. In a nutshell, limited roller is caused by the particular design of the 2D electrical grid the keyswitches are arranged in; aka the matrix. Problems happen when multiple routes are opened up, like this:

Image

Is there anything you can do about it? Actually, no. Use another keyboard. The Model M is also 2KRO, incidentally, as you'd find if you try holding down its WASD keys. Welcome to a new problem! ;)

NKRO isn't just for gamers. I too have found regular typing on particularly poorly designed 2KRO boards (like terminal Model Ms, which are worse than yours) to be infuriating. Thankfully, most boards I have are NKRO. A lot of vintage boards even do it right. You're just unlucky with those specific models.

rheinpfeil

18 Apr 2021, 14:19

Thanks for the answer!

I have read the articles. When I asked the question, I was already afraid that it was made this way. And now I know for sure. In Dutch, “de” (the) is often used. Just like words that end in “lijk” or have the combination “kl” or “lk” in them. So that stipulates a problem with the Apple keyboard. The IBM is not bothered by these combinations.

I tested the wasd combination on the IBM, simultaneously press ws and then the a or the d indeed does not work. I found out there are still more combis. The 2KRO also explains why some complex combinations with four keys do not work on both keyboards. For instance, in Word «command control shift F» to enter Focus mode.

The Logi Craft seems to handle all n-combinations. Well now that I know this, I can also take it into account in my workflow. And maybe in the future I´ll find a nice mechanical vintage board that can do it all. I like the looks of the Siemens keycaps so I´ll do some research on that keyboard.

User avatar
Muirium
µ

18 Apr 2021, 14:33

Rollover bites!

Model Ms (apart from some Terminal models) are usually pretty good for chording modifier keys. I’ve typed on SSKs for years (the tenkeyless space saving version of the regular Model M) and I chord a lot. Shift+Command+Control+F isn’t a combo I’ve tried but it sounds like it should work. What key are you mapping to Command?

The way I have my classic IBM Model Ms setup is with the Alt keys mapped to Command, both Control keys to Option, and Caps Lock to Control. That matches my HHKB and I even map my MacBook’s keyboard with Control left of the A key, for consistency’s sake.

rheinpfeil

18 Apr 2021, 17:35

In the assignment of command, option and control I have used different combinations. On the IBM it is set up as follows:
left control → left option
left alt → left command
right alt → right option
right control → right control

I have tested it a little further. The four-key combination works, but the order of pressing matters on the Apple and the IBM: "Control command shift f" does not work, but "control command f shift" does.

Another addition to the memory muscle to operate the keyboards :)
Last edited by rheinpfeil on 18 Apr 2021, 18:04, edited 1 time in total.

shallot

18 Apr 2021, 17:41

https://github.com/kb-elmo/aek2_usb

Failing that, you can always scrape up some traces and solder diodes in, has the chance to go wrong though

Lanrefni

18 Apr 2021, 20:54

shallot wrote:
18 Apr 2021, 17:41
https://github.com/kb-elmo/aek2_usb

Failing that, you can always scrape up some traces and solder diodes in, has the chance to go wrong though
AEK II has diodes already,so roll over shouldn't be a problem,I'd be checking for a short or bad solder joint,I'd also try a second converter as well.

rheinpfeil

19 Apr 2021, 09:36

Because you wrote that it should work, I took another look. I use Karabiner. A number of Windows shortcuts have been mapped to Mac commands. I deleted the line «control F → command F». And voilà… the «command control shift F» combination works flawlessly (on both boards).

In this case a problem with software instead of hardware. Unfortunately this does not solve the blocking of the «de» and «l kjn» combination.

Thank you!

User avatar
Muirium
µ

19 Apr 2021, 10:40

Didn't expect that!

I did read once the AEK II has hardware rollover issues. Can't remember where now, it wasn't on DT. Someone had dug into the PCB trace and identified the original design shortcuts which caused the problem. That explains why the community PCB replacement Shallot linked to even exists.

Also: ADB—the protocol the AEK II natively speaks—has issues of its own. Can't remember if they're rollover related, so much as simply a protocol limit on typing speed. ADB was designed by Woz in a hurry for the Apple IIgs, and he squeezed everything over 3 lines instead of the usual 4. That sneakiness came at a cost.

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