--- Tony Duell <ard(a)p850ug1.demon.co.uk> wrote:
I had this idea for a keyboard adapter for classic machines, but I
don't understand the 40-pin "keyboard BIOS" microcontroller well
enough to know if it's possible...
I am not sure where the term 'keyboard BIOS' came from, but it can go
back there :-)
I know it's a pre-programmed microcontroller, but in the U.S., if you
go to a PeeCee shop, that is what they call it.
You may not need the PC-compatible 8042 chip for this.
Information on the
serial interface to the keyboard exists as well.
True, it does, but I was investigating if I could use an existing
microcontroller for that or not.
And I would have thought you could program just about
microcontroller to talk to the keyboard on one side and
the RS232 line on the other
Yes, but since this 8042 is already set up to do it, *and* it takes
care of any undocumented or poorly documented "features", I was
thinking it could be a faster/simpler solution.
I know that
the 6402 serial chip can be strapped to operate in a
dumb converter mode...
Although I normally do things like that, this is one time when a
microcontroller would be more efficient, I think.
I was attempting to use the 8042 as the microcontroller in this
circuit without an additional microcontroller that I would have
had to program and debug.
You really want an IBM PC/AT Techref....
OK. That's exactly the kind of answer I was looking for.
You could _trivially_ hang the 8042 keyboard interface
chip off the bus
of either of those CPUs.
It's an alternative I'm considering. All I really need is a way to
use a cheap keyboard, occasionally, not full time, to play with the
innards of what is, essentially, an I/O board with an embedded
microprocessor. I am already going to have a UART, so I wanted to
explore the possibility of using the recieve side to listen to a
keyboard with a minimal amount of stuff in between.
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