> It turns out that the keyboard uses little sponge pads to hold the
> capacitive disks and they have biodegraded into dust.
The correct answer is replace the pads, not the keyboard.
Sources for 8b TTL keyboards (Keytronics)
ROBO5.8 robo58 at optonline.net
<mailto:cctalk%40classiccmp.org?Subject=Sources%20for%208b%20TTL%20keyboards
%20%28Keytronics%29&In-Reply-To=20081124113652.A53673%40shell.lmi.net>
Thu Dec 4 10:03:11 CST 2008
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________________________________
Hi Folks,
It's been interesting taking out my old CP/M stuff and getting it
operational again.
My system uses an 8bit TTL Keytronics Capacitive Sense keyboard. It was
operational for about an hour and then it quit.
It turns out that the keyboard uses little sponge pads to hold the
capacitive disks and they have biodegraded into dust.
So I went looking for an old 8b TTL replacement keyboard. So far no luck.
I also looked for a black box solution that would take an AT or PS/2
keyboard and convert it to a parallel port output. So far no luck.
So let me turn to the experts and ask for advice and suggestions.
Please advise
Robo
-----REPLY-----
Hi! I feel your pain on trying to obtain parallel ASCII keyboards. They
are not easy to find and sometimes when you do they are not compatible or
require extensive modifications to work.
My suggestion is to use a PIC (16F628) to implement a simple serial to
parallel converter. I did this to with a PIC to convert a spare broken
KayPro II keyboard (300 bps serial) to 8 bit parallel with strobe for use
with a Vector Graphic FlashWriter II parallel keyboard interface.
The same could be done with an XT or AT (PS/2) keyboard although a bit more
complex. The software source code examples available on the internet.
One of the N8VEM builders (James) just did a project to add a AT (PS/2)
keyboard to the N8VEM SBC so that might be a good place to start for a
source code example.
Thanks and have a nice day!
Andrew Lynch
Hi Gordon, I mailed you off list but no reply hence this posting.
I'm interested in your pdp11 if you still have it available.
I have a couple of pdp8s but I'd rather like a small 11 also. Like many on
here I was once a DEC systems manager and I've a soft spot for these older
machines.
I live not so far away in Fife by the way.
Bob
--------------------
> Message: 20
> Date: Tue, 25 Nov 2008 20:28:48 +0000
> From: Gordon JC Pearce MM3YEQ <gordonjcp at gjcp.net>
> Subject: New home sought for a PDP-11
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Message-ID: <492C6000.6020609 at gjcp.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi all,
> I've come to the conclusion that it's time my PDP11/73 went to a new
> home. Not a terribly easy decision to make, but I just don't have space
> to even get to it to switch it on just now and I'd rather see someone
> else get some use out of it.
>
> Anyway, here's the spec:
>
>
> PDP11/73 in a large Baydel cabinet with a 40M-ish MFM drive
> RX02 floppies
> 2 x RL02 plus a spare RL02
> 2 x CIT101 terminals
> VT520 terminal
> VT220 terminal
> LA36, spare ribbons and paper
> spare boards including 11/03 bits, a couple of opto-isolated I/O boards
> and some ADC boards
> DEQNA
> about a dozen RL02 packs
> large box of RX02 disks
> RT-11 V5.2 manuals
>
> Pick up in Glasgow. You'll need a van, although not a very big one, to
> shift it. A large estate car would be too small unless you broke the
> rack down into panels - a PITA, I've done it before though.
>
> Mail me on- or off-list if you're interested.
>
> Gordon
>
> *********************
>
Does anyone know anything about the HP13264 Data Link Interface, or the
network (?) it was connected to? It's mentioned in passing in the
documentation for the HP98268 comms card, and I've just bought one.
Let me describe ehat I've discovered so far.
Physically it's a plastic box of the same design as used for many other
HP intefaces (like the 82164 HPIL-RS232 interface). 2 cables come out of
it. One ends in a 50 pin Microribbon plug, which is the HP 'RS232' port
connector. The other is a figure-of-8 cable ending in a strange 6-contact
plug that I'll describe more later. On top are 2 LEDs marked 'Link' and
'Transmit'.
Inside there's a PCB containg a few standard chips, some passives, and 2
optoisolators (one single, one dual).
It draws power -- +5V, +12V, -12V from the HP RS232 port (power lines
were provided on this connector). The only RS232 signals used are TxD,
RxD and RTTS (which is strapped to CTS). The last is used as a transmit
enable.
There's an isolated PSU on the PCB, driven by a 555 astable. It provides
6.7V to the circuity on the 'network side' of the optoisolators.
The TxD and RTS signals are bufferd to TTL levels (1489 chip), and fed
into the dual optoisolator. The RTS signal also drives the 'Transmit'
LED. On the other side of the optoisolators, they go to 4011 NAND gates,
which drive 4 transitors as a full-H driver. These drive the netowrk
cable (there are 3 siganls on this cable -- Sh (Shield) which is
connected to the ground of the isolated PSU, and +, - which are driven by
this full-H circuit).
The network cable is monitoed by a 311 comparator. Its output drives the
remaining optoisolator, the output of which is buffered to RS232 levels
(1488) and then drives the RxD signal to the computer. This optoisolator
also drives a circuit that controls the 'Link' LED, such that a '1' on
the network cable flashes said LED. If the network cable is in a steady
state (no matter what state), the LED is off.
Note that the receiver is always enabled, a computer monitors its own
trasmission. Presumably that's used for collision detection.
There are 2 3-way terminal blocks on the PCB for the cable to the network
connector. Corresponding terminals are linked by PCB tracks. The cable is
a figure-of-8 thing with each part being a screend (twisted?) pair.
Obviously the inners go to the '+' and '-' terminals on the PCB.
This cable ends in a connector that's a bit like an overgrown microribbon
connector without the outer hosuing, but with only 6 contacts. There's a
picture of the interface and this connector on the Austrralian HP museum
site. The 'business end' looks a bit like this :
-
| |
-==--==--==-- |
| |
-==--==--==-- |
| |
-
Where == is a contact area (6 in all)
That would be looking at the face of the socket, which must have a 'T'
shapped cutout in it to allow the plug to go in. I assume there are6
contact springs in the socekt to connect otther cotnact areas on the
plug.
Now, corresponding cotacts on the 2 sides of the plug are connected
together. But not directly inside the plug, but rather from one side of
the plug, up one of thr pairs of the figure-of-8 cable, then via PCB
tracks to the corresponding wire in the other pair, back down the cable,
and to the contact on the other side of the plug. This means that the
figure of 8 cable won't appears as a 'stub' on the main cable.
I would guess that the socket has contacts that touch when the plug is
removed, thus completing the connections I've just mentioend.
This looks a bit likea French teleohone socket, but I'd heard that this
was normally an 8 pin device, withe the other contacts on the 'head of
the T (right hand part of my diagram). Whether I could use such a socket
andwhether it would need modification I don't know. I also don't know if
such sockets nroammly short corresponding contacts on the 2 sides if no
plug is connected (as I mentioned in the last paragraph, this would be
desireable here).
So, does anyone know anything about this device? What was it used for?
What was it used with? What was the socket? Protocol? Any manuals/docs
o the web (a google search found nothing useful)?
Thanks in advance for any help
-tony
If anyone is curious about what an IBM 4" floppy drive looks like, I just uploaded a picture
and the patent for it to http://bitsavers.org/pdf/ibm/floppyhttp://www.weblog.com/comments.aspx?blogid=30290&postid=71765
4-inch floppy diskettes
In the mid-80s, IBM developed a 4-inch floppy diskette, the Demidiskette. This program was driven by aggressive cost goals, but missed the pulse of the industry. The prospective users, both inside and
outside IBM, preferred standardization to what by release time were small cost reductions, and were unwilling to retool packaging, interface chips and applications for a proprietary design. The
product never appeared in the light of day, and IBM wrote off several hundred million dollars of development and manufacturing facility.
CHM appears to have one
http://www.computerhistory.org/collections/accession/X1140.93
Mismarked at 5 1/4" (grrrr..)
And a disk
http://www.computerhistory.org/collections/accession/102667528
Just wondering if anyone on the list won the Data General 6045 Disk Drive that was on the GL in Columbus, Ohio, recently? Just want to know if it went to a good home or if someone won the lot for the other items that were included.
If you saw the number of bad units we just dumpstered at the Zebra
Systems warehouse, you'd blanch.
I quipped to Stewart that we had a dumpster full of perfectly good door
stops.... LOL!
Not to mention Monitor wedges (I used to use a broken unit to wedge my
Monochrome Monitor to the right angle).
The sheer computing power in all those trashed units just started to
approach my cell phone. LOL!
Al
Available for postage from Denmark :
Longshine LCS-6210D
Supports 2 MFM ST506/ST412 drives
Pulled from XT compatible
No floppies
Max. 16 heads and 1024 cylinders
Nico
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