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Re: Moveable Keyboard On An ][+

Michael Black wrote:

"Robert C." (robc638killspam@sympatico.ca) writes:
I was thinking on making my ][+'s keyboard removeable. I know using an IBM keyboard is out of the question as it uses a very odd encoding technique. What kind of encoding does a Mac keyboard use? How difficult would it be to decode the serial line into a parallel signal in order to plug it into the connector at the motherboard?
~Robert. 



Surely the simplest thing is to open the Apple case, unscrew the keyboard,
install that in a case, and then run a cable between the two.  Likely
can't be too long a cable, because it's not originally intended to
drive a long cable.


But there are no fast signals on it, so 6'-10' should be fine,
though some shielding from interference may be useful.


I did something similar to this with my Radio Shack Color Computer,
though in that case the keyboard was merely the matrix, and the scanning was on the actual computer board, but I was able to use 
a length of ribbon cable that was long enough that I could remote
the computer.

It used to be that pretty much all keyboards were ASCII encoded,
if they had the encoder on the board, and some would even include
a UART to output the ASCII in serial form.

But then the "IBM PC" came along, and the keyboard did not use
ASCII.  Same with the Mac keyboards.  So it's not just a matter
of doing serial to parallel conversion, but key code conversion too.


That's because modern keyboards are much more general, allowing
the independent sensing of "key down" and "key up" for all keys
on the keyboard.  This means that, like a musical keybaord, they
can be used to play "chords"--like Ctl-Alt-DEL, or even A, B, C.  ;-)


I've mentioned before having a clone that had a remote keyboard.
It used an "IBM" type keyboard, with the ROM changed so it was
outputting regular ASCII.  Plugged into the socket where the keyboard
normall goes on the Apple II, was a tiny board with not much more
than a serial to parallel shift register, to do the serial to parallel
conversion. This scheme meant there was no need for conversion at
the computer, and the only reason that serial to parallel converter
was needed was because the hardware of the computer was set up
for serial output.


Using a serial link from a parallel ASCII-encoded keyboard to
a parallel-ASCII Apple II clone just allows a cable with fewer
wires, at the expense of a couple of shift registers plus clocking.


If moving the Apple II keyboard out of the case isn't a suitable
solution, you could always dig around for an ASCII keyboard in a
case, though that may take time finding one at this point.

Or as I once suggested here, but have not tried, you could take
something like the Commodore 64, and have it echo the keyboard
to the parallel port, which you'd then feed to the Apple keyboard
encoder  socket.  You get the keyboard in a case.  Though you'd
either have to type in a program every time you turned on the Commodore
to do the echoing, or go to the trouble of modifying the 64's
ROM so it does this automatically.


That would work fine.

-michael

8-voice music synthesizer using NadaNet networking!
Home page:  http://members.aol.com/MJMahon/