On Tue, Aug 19, 2008 at 09:33:03PM -0600, Michael B. Brutman wrote:
Ethan Dicks wrote:
Thanks for the writeup. I look forward to trying
this out on my LPFKs
when I get home.
The protocol you describe is radically different from the one that
codeninja describes at
http://codeninja.de/lpfk/ ...
I don't know where the codeninja guy got his information. After all of
the research that I've done I don't think that he has a normal LPFK.
His came from an engineering department and may have been modified, just
like Dave & the guys here were talking about modifying theirs.
That's entirely possible. I was just wondering if there were two
variants from IBM or not, but I suppose an engineering student
could have replaced the MCU.
I have a blank overlay and a CADAM overlay that labels
the keystrokes.
I will probably scan the blank shortly so that people can download and
make their own.
Nice. Thank you.
I think in practice the LEDs were used to indicate
functions that were
toggled on. And as you mentioned, they could also be set to show you
what functions were legal/available to select.
OK. That seemed to be the obvious thing.
The only real wrinkle with this protocol is that the
host has to
'confirm' each keypress by relighting the entire keyboard. (Their is no
way to change just one key - you have to send the entire bitmap down.)
It makes sense though - selecting one key could often have a side-effect
on what other keys/functions would be available.
Sure. It's also easier to implement.
I decided to be painful to myself and I fired up the
PCjr and Zbasic, a
crufty old BASIC compiler. Zbasic is nice because it supports a
primitive form of structured BASIC, but it's definitely got some bugs in
the COM handling code. The PCjr is only spec'ed to handle up to 2400
bps, but for single character transmissions like this it is doing fine.
Not to get too far afield, but is the limitation something like interrupt
response time? Reliance on the slow IBM BIOS routines?
I'm looking forward to running a telnet BBS on it
and using the keypad
as a combination status indicator/input device. That way I can know how
busy the machine is an interact with it in a limited way without turning
the monitor on.
I was also thinking of using the LEDs for checking things at a glance
without either turning the monitor on, or having to move windows around
(that's one of the things I use LCDproc for). Also... with the keys,
it'd be possible to switch to the next song on xmms, etc. (another thing
I use LCDproc for).
Evil grin .. each lit button represents a connection
to kill. :-)
Nice! Real BOFH stuff! "Goodbye, Butterman! *click*"
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 20-Aug-2008 at 02:50 Z
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Ethan.Dicks at
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