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Re-routing custom keys on a Tandberg TDV 5000

Posted: 06 Sep 2018, 21:27
by snufflecat
Hi guys,

So I recently acquired two Tandberg keyboards (TDV5000 series) and have had some time to play around with them.

For those who don't know they have a small heap of "custom" keycaps such as "REMOVE", "COMPOSE CHR", "FIND" and so on.
When I fired up Switch hitter I found that these actually register as regular letters. "Compose chr", for example, registers simply as "W" etc.

Now this is all fine and good, but I'd really love to be able to re-use these caps to do other things. Compose CHR for example would be great to use as an alternative Win-key. My trial for Key Manager has expired (and to be fair the software was a bit advanced for my taste), so I'm looking for software that can do the job.

The big question is: Is it even possible to re-route the keys when they already register as other keys? Meaning, if I re-routed Compose CHR to work as a Windows-key, would it cause my W-key to do the same? From what I can tell from Switch Hitter clicking the custom keys generate the same signal/code that the computer sees.

Any advice and input here would be amazing. :)

Posted: 06 Sep 2018, 21:57
by Muirium
This the keyboard?

wiki/Tandberg_Display_TDV_5010

If yours is PS/2, you could try Soarer’s Converter to make it into a programmable USB keyboard. You definitely need those keys to have unique key codes, however, or even Soarer’s can’t tell them apart. I suspect the keys you mention *do* have their own codes, but it’s just a hunch. I don’t know Tandberg.

Edit…

From the Wiki:
To ease production, all keyboards of the series are fully equipped with switches, 20 of which are extra beyond the standard. The PS/2 controller tags them with a 0x80 prefix.
Okay so those keys are sending something different. But I can’t say I understand what that means exactly. Can Soarer’s Converter tell what’s going on? Or does tandberg terminal PS/2 require its own converter?

Posted: 08 Sep 2018, 00:57
by OleVoip
What it means exactly is that if one of the extra keys is pressed, the keyboard first sends scan code 0x80 and then the specific code for the key. For instance, the make code for "COMPOSE CHR" is the sequence 0x80, 0x1D. The 0x80 prefix gets ignored; hence, Switch Hitter sees only 0x1D and thinks its "W". You would need a converter that does not ignore 0x80 but switches to another key map for just the next scan code.

Posted: 10 Sep 2018, 21:37
by snufflecat
OleVoip wrote: What it means exactly is that if one of the extra keys is pressed, the keyboard first sends scan code 0x80 and then the specific code for the key. For instance, the make code for "COMPOSE CHR" is the sequence 0x80, 0x1D. The 0x80 prefix gets ignored; hence, Switch Hitter sees only 0x1D and thinks its "W". You would need a converter that does not ignore 0x80 but switches to another key map for just the next scan code.
Hmm, I see. So in other words if I want to use the custom keys I can't solely rely on only connecting it via PS2? Basically re-trace the matrix and wire it up to a controller of my choosing?

Posted: 12 Sep 2018, 13:10
by OleVoip
No need to rewire. You only need to make a ps2 to usb converter and modify its software to swallow the 0x80 prefix and remap the code following it. For instance, you could use Hasu's code, https://github.com/tmk/tmk_keyboard, and change the matrix_scan function in converter/ps2_usb/matrix.c accordingly.