Date   : Thu, 01 Sep 1994 14:57:33 WET DST
From   : Bonfield James <jkb@...>
Subject: Aha! keyboard (nearly) working

Would you credit it! I've been sweating blood over this blasted keyboard. Yet
oddly enough it's actually been working for FAR longer than I thought! I just
couldn't get it working. I kept spotting minor problems, and then fixing
them and analysing the debug output.

In the end I resorted to cheating - I made a few changes to James Fidell's
emulator to produce better debug output and then ran both his and mine and did
some comparisons.

Suprisingly this showed me that both his and mine were doing the same thing
(within reason). Hmm - odd!

So, I removed all my debugging output, and tested mine again - it's working!
It appears that my problems were all due to the debugging code slowing things
down and due to my somewhat iffy UNIX itimer usage was confusing issues
slightly. This caused stacking interrupts and earlier these were being
handled incorrectly (I'd forgotten to SEI before executing the interrupt).

Since that's been fixed it's actually all been working OK! It's just that my
debugging output was so volumous that I hadn't spotted it - sigh.

Well, I say ok - actually I'm currently getting the key I to display 9 all the
while (trivial fix in my keyboard matrix) and the interrupts occasionally stop
getting generated (due to a bug in my timer queueing code).

       A pleased (at long last) James B.

PS. It's not really that hard you know - so people shouldn't call it the
'infamous keyboard code'. My problems were mainly my own doing :-(