Mailinglist Archive: opensuse (1956 mails)

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Re: [opensuse] keyboards, was: New desktop
  • From: James Knott <james.knott@xxxxxxxxxx>
  • Date: Fri, 10 Aug 2007 16:23:55 -0400
  • Message-id: <46BCC95B.8080408@xxxxxxxxxx>
Doug McGarrett wrote:
On Thursday 09 August 2007 21:52, James Knott wrote:
Robert Smits wrote:
On Wednesday 08 August 2007 19:08, James Knott wrote:
Incidentally, many years ago, I bought a huge Cherry keyboard, without
any encoder logic.  I designed & built my own encoder and used that
keyboard with my IMSAI 8080.
/snip/

As long as we're reminiscing here, I must jump in with this:  In 1981 I bought
the Big Board CPM computer, which came as a kit of components, with no
peripherals.  I found a 10" monitor and a keyboard from someplace that had
a shift key, but only produced upper-case keycodes.  It must have been used
with a teletype machine or something similar.  Not being a programmer,
certainly not in assembler, I built (with some trial and error, since I'm also
not a digital but an RF engineer) a converter out of TTL logic to produce
both upper and lower case characters under control of the shift key. The Big Board would take parallel keyboard input, as well as serial, so this was not too difficult to do. (Genuine serial k/b's usually only came as part of a terminal, which was pretty darned expensive back in the day.)

In another aside, I found, with the help of another engineer who was experienced in video, that the BB was deficient in video bandwidth, so I figured out how to cure that, and wrote it up for the Micro-Cornucopia.
They sent me a Tee-shirt, which I still have, marked "AUTHOR".

--doug
That Cherry keyboard was unique. The standard keyboard keys had white key tops and all the other keys, function, number pad etc., had gray tops. There were almost as many gray as white keys. That keyboard was wired as two separate keyboards, each with it's own scanning matrix, in one physical package. The white keys were one keyboard and the gray keys the other. My encoder combined the two into one big keyboard, with the 8th bit used to signify which set of keys was in use. I used a 2716 EPROM to convert the scan codes to ASCII and I included auto repeat etc. It worked well. Some time after that, I was taking a digital logics course at Ryerson, in Toronto. One of the projects was to build a hex keyboard. I just showed the instructor what I had designed & built and that was good enough to get full marks for the project. ;-) BTW, the only reason I took that course, was because it was a compulsory prerequisite for some other courses I wanted to take. There wasn't much I actually learned in it, though it was fun to play with the Commodore CBM we used to connect to some projects. I also became an "assistant instructor", helping the other students with their projects.



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