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Re: How to program my own keyboard driver?

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On Fri, 20 Sep 2013 06:42:11 -0400, Ruud Baltissen <rbaltissen@gmail.com>  
wrote:

>> I'm surprised you're not familiar with these Ruud since ....
>
> Of course I'm familiar with them.  But the first three [won't work]

Well, you only need one interface that works, e.g., USB, PS/2, AT, XT.
It's likely there are other projects out there if you search for them.

I seem to recall one that connected to AT.  I thought it was in the
C= Hacking electronic magazine, but I couldn't locate it...

> But the first three ones have an USB interface which, without
> a DOS driver, are worthless.

Standard USB keyboards for IBM compatible PCs fallback to using the
PS/2 protocol on USB wiring when they don't receive a USB handshake.
This is so the USB to PS/2 adapters work.

Could that could be useful?

I.e., a USB keyboard supports both USB and PS/2 protocols but is
wired for USB.  That's why the purple USB keyboard to PS/2 adapters
work.  If you use the purple USB keyboard to PS/2 adapter and connect
to PS/2, then keyboard works as PS/2.  You could also rewire the USB
connector to PS/2 yourself.  PS/2 to AT adapters are available too.
They just change the wiring also.  The green USB mice to PS/2 adapters
work the same way, but the wiring is different, opposite.

It's probably unlikely that those projects use standard keyboard
circuitry that would support both USB and PS/2 modes.

> In fact I'm making my own keyboard adapter for later. I disassembled
> an IBM keyboard which has a 14 * 8 matrix (IIRC).
>
> Two [possabilities]:
> - I connect the CBM keyboard directly and translate the output
> of the keyboard first.

That seems reasonable.  Of course, all the encoding of keys will
be wrong since the matrix is different.

> - I rewire the CBM keyboard internally as good as possible.
> And then there is still some translating to do.

That possibly damages the keyboard and could result in wiring issues.

> IMHO the LPT port hack is easier.

The pins are there for it.  The logic isn't.  I.e., software.

Of course, a newer PC might not have an external LPT port.

RS232C/D is more than fast enough, but you need serializing
logic, e.g., UART etc, logic to adjust voltage levels,
scanning logic, etc.

USB will be available for a while, and hopefully PS/2 too.  Some
machines can't enter the BIOS in certain configurations without a
PS/2 keyboard, requiring a CMOS reset if one is not available.


Rod Pemberton

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Thread

How to program my own keyboard driver? Ruud Baltissen <rbaltissen@gmail.com> - 2013-09-19 09:26 -0700
  Re: How to program my own keyboard driver? JJ <duh@nah.meh> - 2013-09-20 06:02 +0700
    Re: How to program my own keyboard driver? Ruud Baltissen <rbaltissen@gmail.com> - 2013-09-20 03:07 -0700
  Re: How to program my own keyboard driver? Ross Ridge <rridge@csclub.uwaterloo.ca> - 2013-09-20 00:03 -0400
    Re: How to program my own keyboard driver? Ruud Baltissen <rbaltissen@gmail.com> - 2013-09-20 03:38 -0700
      Re: How to program my own keyboard driver? Ross Ridge <rridge@csclub.uwaterloo.ca> - 2013-09-20 09:19 -0400
  Re: How to program my own keyboard driver? "Rod Pemberton" <dont_use_email@nohavenotit.com> - 2013-09-20 00:53 -0400
    Re: How to program my own keyboard driver? Ruud Baltissen <rbaltissen@gmail.com> - 2013-09-20 03:42 -0700
      Re: How to program my own keyboard driver? Ross Ridge <rridge@csclub.uwaterloo.ca> - 2013-09-20 09:31 -0400
      Re: How to program my own keyboard driver? "Rod Pemberton" <dont_use_email@nohavenotit.com> - 2013-09-20 15:07 -0400
        Re: How to program my own keyboard driver? Ross Ridge <rridge@csclub.uwaterloo.ca> - 2013-09-21 11:56 -0400
  Re: How to program my own keyboard driver? "Bill Buckels" <bbuckels@mts.net> - 2013-09-20 20:21 -0500

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