23 Dec
2013
23 Dec
'13
12:49 a.m.
Hi, All,
Years after we were discussing the LPFK in detail, I have managed to
be home long enough to find mine and hook them up. I've also dug into
the innards a little bit to understand how to wire up a cable, and it
brings me to a question... what is pin 4?
According to the old discussions, pin 4 was described as +5V or "+5V
through a pullup" since there was clearly not a direct path from pin 3
to pin 4. My tracing of the board shows me that pin 3 is indeed +5V
in, but pin 4 is connected to +5V through a signal diode, *and* to
ground through a diode, *and* (through a small resistor) to both
inputs on one of the gates in the 74LS00 whose output is RESET.
So... it looks like a diode-clamped input for resetting the 8031. My
question is, given that one diode drop is 0.7V (I don't think these
are zeners, at least they are in orange glass packages with a yellow
stripe, not a silver package with black stripe and numbers like the
zeners I recognize), can you safely put more than 6V on this input or
not? i.e., is it meant to be connected to RTS or DTR so that the host
can easily reset it? I know more modern serial ports (those without
1488s and 1489s, for instance) don't often hit +/-12V, but I know
nothing about what the LPFK was supposed to connect to, so I can't
guess what serial voltages the LPFK would have to accommodate. Does
anyone have a pinout or a good description of the original IBM cable?
To connect up my LPFKs, I bisected an old 8-pin DIN cable and added a
DE9, and for the interface, hacked a Keyspan-brand RS-232 dongle to
sever RI from pin 9 and to bring up +5V from the USB connector. I've
seen other serial devices (like those used with a POS) that have
power-over-serial on pin 9, so I know it was commonly done for
embedded devices, but I can't seem to find a good name for the
practice (I was planning on marking altered devices with "P9" so I
know that pin 9 is powered.
It's fun finally getting some practical experience on the real
hardware and to see the sample code I wrote five years ago for Phil
Pemberton's library in action.
Thanks for any info,
-ethan
24 Dec
24 Dec
4:28 a.m.
On 23/12/13 08:49, Ethan Dicks wrote:
It's fun finally getting some practical experience
on the real
hardware and to see the sample code I wrote five years ago for Phil
Pemberton's library in action.
You know, I still haven't found a use for my LPFKs. I hacked together a
version of Conway's "game of life", but that was it...
In my case I used an FTDI USB RS232 cable and a MAX233 to connect it to
a PC. The reset pin you mentioned was left floating (IIRC).
One of these days I'll think of a use for them... one of these days...
--
Phil.
philpem at philpem.me.uk
http://www.philpem.me.uk/
25 Dec
25 Dec
3:45 p.m.
In article <52B97DEA.1090401 at philpem.me.uk>,
Philip Pemberton <philpem at philpem.me.uk> writes:
On 23/12/13 08:49, Ethan Dicks wrote:
The original application is pre-GUI CAD with lots of menu choices and
modes. Once you have a GUI with fancy dialog boxes, these button
boxes become less useful for navigating a complex application --
although dial boxes are still quite useful as there's nothing like
having 3 dials for x/y/z rotations.
--
"The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
The Computer Graphics Museum <http://ComputerGraphicsMuseum.org>
The Terminals Wiki <http://terminals.classiccmp.org>
Legalize Adulthood! (my blog) <http://LegalizeAdulthood.wordpress.com>
It's fun finally getting some practical
experience on the real
hardware and to see the sample code I wrote five years ago for Phil
Pemberton's library in action.
You know, I still haven't found a use for my LPFKs.
8:08 p.m.
On Tue, Dec 24, 2013 at 7:28 AM, Philip Pemberton <philpem at philpem.me.uk> wrote:
On 23/12/13 08:49, Ethan Dicks wrote:
I was thinking about using it with Celestia for navigating around the Milky Way.
It's fun finally getting some practical
experience on the real
hardware and to see the sample code I wrote five years ago for Phil
Pemberton's library in action.
You know, I still haven't found a use for my LPFKs. I hacked together a
version of Conway's "game of life", but that was it... In my case I used an FTDI USB RS232 cable and a MAX233
to connect it to
a PC. The reset pin you mentioned was left floating (IIRC).
I can see leaving it floating. I was posting the question because the
original codeninja page called it +5v, and the early discussions here
called it "+5 through a pull-up?".
One of these days I'll think of a use for them...
one of these days...
I've also considered using it as an input panel for one of the players
for the Starship bridge simulator Artemis.
-ethan
26 Dec
26 Dec
5:13 p.m.
In article <CAALmim=WqkuG3LqfgM_9gu5888+pYN+xGeq2pA+vQVyU93QFUA at mail.gmail.com>,
Ethan Dicks <ethan.dicks at gmail.com> writes:
I was thinking about using it with Celestia for
navigating around the Milky
Way.
Some other mundane ideas:
- associate each key with a keyboard macro, press the key and it's as
if you typed a sequence of keystrokes on the keyboard. Not much
point in illuminating individual buttons in this case unless you
want to make the macros context sensitive and illuminate only those
keys whose macros are applicable in the detected context.
- associate each key with a web browser shortcut. Pressing the key
navigates to that shortcut and the LED stays lit until the address
changes.
- window manager shortcuts -- synthesize various WIMP style events
when the key is pressed.
- integrate it as an X input extension device. This would take some
programming, but shouldn't be too hard.
- media player interface. Stop, Play, Pause, FFwd, Rewind, etc.
I've also considered using it as an input panel
for one of the players
for the Starship bridge simulator Artemis.
More classiccmp-ish -- PDP-8/11 front panel toggle switches?
--
"The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
The Computer Graphics Museum <http://ComputerGraphicsMuseum.org>
The Terminals Wiki <http://terminals.classiccmp.org>
Legalize Adulthood! (my blog) <http://LegalizeAdulthood.wordpress.com>
6:06 p.m.
On Thu, Dec 26, 2013 at 8:13 PM, Richard <legalize at xmission.com> wrote:
- integrate it as an X input extension device. This
would take some
programming, but shouldn't be too hard.
I think that's quite do-able.
- media player interface. Stop, Play, Pause, FFwd,
Rewind, etc.
I've done media player hacks (XMMS) with LCDproc that can use
serially-attached LCDs and such. There is no driver presently for an
LPFK as an input device, but I have written drivers before and it's
not that hard.
You could use it for a track indicator/selector as well. Use the
bottom row for control (stop/play/etc) and the middle 24 buttons to
show what track is currently playing, then skip to any random track by
pressing one button.
More classiccmp-ish -- PDP-8/11 front panel toggle
switches?
With an arrangement of 4-6-6-6-6-4, you _could_ use 2 rows for 12
bits, but it's a bit odd to think of PDP-8 instructions as pairs of
6-bit numbers. The keypad geometry is a bit odd for the PDP-11.
One could also use part of it as a hex keypad, so it could be used as
an 1802 front panel as well, but I'd want to stick a microcontroller
between the LPFK and the 1802 and have lines on the microcontroller
twiddle the lines on the 1802 (as was done with later Elf designs and
the 74c922 keypad controller).
With a bit of code and a solenoid, it could become a
needlessly-complex digital lock (that plays Life until you want to
open the door).
-ethan
6:42 p.m.
On 12/26/2013 06:06 PM, Ethan Dicks wrote:
With a bit of code and a solenoid, it could become a
needlessly-complex digital lock (that plays Life until you want to
open the door).
I've considered getting one and writing some code to work with Sibelius
(musical transcription tool), which uses modal keystrokes to get
something. It would be quite useful to have an illuminated keypad that
says "You're inputting accented staccato dotted quavers now".
Currently, you have to look at the lower right corner of the display to
see what mode you're in. Forget to do that and you get some pretty
"interesting" results that resemble what a chimpanzee might create.
Don't have one so never got around to doing one.
--Chuck
7:50 p.m.
On 12/26/2013 7:42 PM, Chuck Guzis wrote:
On 12/26/2013 06:06 PM, Ethan Dicks wrote:
Well just call the CD, Music to eat ants by.
With a bit of code and a solenoid, it could
become a
needlessly-complex digital lock (that plays Life until you want to
open the door).
I've considered getting one and writing some code to work with Sibelius
(musical transcription tool), which uses modal keystrokes to get
something. It would be quite useful to have an illuminated keypad that
says "You're inputting accented staccato dotted quavers now".
Currently, you have to look at the lower right corner of the display to
see what mode you're in. Forget to do that and you get some pretty
"interesting" results that resemble what a chimpanzee might create.
Don't have one so never got around to doing one.
--Chuck
Ben.
3795
days inactive
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days old
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