Re: Possible to adapt a //e keyboard to PC?

[mjmahon@aol.com (Michael J. Mahon)]

Scott Alfter replied:

>In article <krudnUjWHYQmPk6iRVn-tA@comcast.com>,
>Bill Garber <willy46pa@comcast.net> wrote:
>>"Scott Alfter" <salfter@salfter.dyndns.org> wrote in message
>>news:LVMAb.24525$o9.17195@fed1read07...
>>: Speaking of which, do you know of anything that would adapt a PS/2
>>: keyboard to a II+?  Searching Google for parallel ASCII keyboards (what
>>: the II+ uses) didn't turn up much, and the keyboard in mine is flaky.
>>
>>Vince Briel was working on a PS/2 adapter for his Apple I replica. I
>>believe he was also converting the design to work with the Apple II as
>>well, but I don't know if he has any completed.
>
>Looking at the (sparse) information available for the Replica I, the
>translation looks like it's done with a microcontroller.  If more technical
>information were available, it might be possible to take out just the
>keyboard-conversion part of the circuit and build that as a keyboard
>translator.
>
>I've had half a thought of picking up a cheap keyboard and rewiring it into
>something that might work with the II+'s keyboard encoder.  I suspect that
>hack would end up looking ugly as hell and wouldn't work all that well. 
>
>Searching Google and eBay for parallel ASCII keyboards or keyboard adapters
>hasn't turned up much that's useful either.  This page is the closest to
>useful that I've found:
>
>http://www.izabella.freeuk.com/html/6809_project.html
>
>It uses a 6809 to read a PS/2 keyboard and produce parallel or serial ASCII
>data.  Something that's simpler WRT hardware would be nice, but I suppose
>this is a start.

There are several PC keyboard adaptations on the web, and most of
them use a PIC single-chip microcontroller.  Since the PC keyboard
protocol is pretty messy, and the tables required are extensive, it's
probably worthwhile to scavenge already-written code, or even an
already-designed PC keygoard-to-parallel converter, for example:

http://www.cloud9tech.com/Hardware/AT%20Keyboard.html

which interfaces a PC keyboard to a TRS-80 Color Computer, or

http://www.beyondlogic.org/keyboard/keybrd.htm

which contains a lucid explanation of the PC keyboard and shows
the design of a PC keyboard-to-serial ASCII using a 68HC705
microcontroller.  It would be easy to skip the conversion to serial
and output ASCII using one of the microcontroller's output ports.

As you can see, though, it _will_ take a computer, or at least a
microcontroller, to interface to a PC keyboard (just as it would
to interface to an ADB keyboard).

-michael

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