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Re: Keyboard replacement

Posted: 29 Apr 2018 23:33
by Dave
First revision of the PCB, fitted to my MTX

(The MTX keyboard connector has been disconnected from the pass-thorugh connector for the photo)

With Bill's latest Propeller code, the board now supports both USB and PS/2 keyboards, the appropriate keyboard type is selected by the jumper above the Propeller chip.

Re: Keyboard replacement

Posted: 30 Apr 2018 15:43
by thewiz

Re: Keyboard replacement

Posted: 01 May 2018 00:15
by 1024MAK
Smashing! 8-)


Re: Keyboard replacement

Posted: 03 May 2018 14:33
by Bill B
Dave has now written up the keyboard interface here.

He describes the issue with keys which are in different shift states on MTX and PC keyboards. An issue common with MEMU, and for which we use the same solution. He also mentions the "Scroll Lock" option which takes advantage of the three unused keyboard matrix positions to provide additional mappings, with the correct shift state, for most of the PC keys (the one exception being back quote).

What he does not mention is that we also have loadable software for both SDX and CP/M to enable this "Scroll Lock" mapping to be used without requiring any changes to the MTX ROMs. This makes typing a lot less painfull for those of us whos fingers have become habituated to the PC keyboard layout.

For CP/M this works by patching the CP/M BOS in high memory.

For the SDX a small routine is loaded between the sound buffers and system variables, whch hooks into an SDX call vector to provide the additional keyboard decoding.

Re: Keyboard replacement

Posted: 12 May 2018 20:49
by Martin A
Dave's sent me a V1.0 "production" PCB of the keyboard interface, which I've made up and tested this afternoon.

Adding that to the test MTX, which has a CFX-II board fitted, gives me access to both modern keyboards (well relatively modern since that keyboard is PS2) and VGA screens.
Switchboxed.jpg (70.01 KiB) Viewed 1069 times
So having tested the above configuration, I wired up the mechanical switchbox you can see in the lower right hand corner of the picture

The MTX and PC now share the same keyboard and display, I guess there's not too many other setups like that in the country right now!

The MTX isn't even in sight. That's on the workbench off camera to the right.

Re: Keyboard replacement

Posted: 12 May 2018 20:57
by Dave

A Memotech MTX through a KVM !