Apple II+ Keyboard Encoder

From: Richard Erlacher <edick_at_idcomm.com>
Date: Tue Aug 21 16:59:36 2001

The GRI version of the keyboard uses a customed version of a 40-pin GI keyboard
encoder. If one has the old data books lying about (which I may ???) then one
could work out the rows and columns, and simply add a translation (lookup)
EPROM, couldn't one?

It's been done before, though I have misplaced the EPROM I once used, having
bought a couple of nice keyboards that turned out not to produce the desired
codes. This wasn't, of course, done for an Apple ...

Dick

----- Original Message -----
From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, August 21, 2001 3:03 PM
Subject: Re: Apple II+ Keyboard Encoder


> >
> > My thoughts exactly, Tony. There are even enough app-notes dealing with
this
> > problem that one should be able to find one for nearly any single-chipper.
The
>
> Sure... You want a microcontroller with a fair number of I/O lines (7
> data bits + strobe to the host, shift/control/repeat key inputs, key
> matrix lines) so an 18 pin PIC would not be a good choice (you'd need so
> many extra TTL chips to get the I/O that you might as well build the
> whole thing in TTL :-)). But an 8748 or 8751 or 6811-series, or... would
> be fine.
>
> > trick is to find the details on the old MM5740 to enable one to emulate it
in a
>
> If it is that version of the keyboard, the schematic (including the
> pinout of the MM5740, at least the pins that are used) is in the Apple ][
> Reference Manual (it's Figure 17, page 101 in my edition). You also know
> what codes the keyboard should send to the Apple mainboard, so it's not
> going to be hard to work out what to do...
>
> > single-chipper that can subsequently be patched into the application
circuit.
> > Given an i875x or even i8748, that shouldn't be too hard. It's really a
> > preference issue once one gets to that point.
>
> Agreed.... Pick the chip you know best -- any of them will be suitable :-)
>
> -tony
>
>
Received on Tue Aug 21 2001 - 16:59:36 BST

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