see below, plz.
Dick
----- Original Message -----
From: "ajp166" <ajp166_at_bellatlantic.net>
To: <classiccmp_at_classiccmp.org>
Sent: Sunday, April 15, 2001 9:42 AM
Subject: Re: Kim / Commie keypads
>
> -----Original Message-----
> From: Ross Archer <dogbert_at_mindless.com>
>
>
> >I think the outboard keyboard & case idea is excellent, and a fun "hour
> at a
> >time"kind of project to tinker with whenever bored. :) I already took
> apart one
> >broke >keyboard in my boneyard -- it was a membrane type. <:-(
>
>
> The keyboard was the common type similar if not the same as most
> calculators of the time used. Simple XY matrix of switches and easily
> replaced.
>
If that were true, this entire thread would not have occurred. The problem with
most of these matrix keypads in a single, solid, monolithically-molded assembly
is that you can't remove a switch and replace it, hence, you have to replace the
entire thing. If it's not an exact replacement, you're out of luck, because it
has to FIT on the board, else the leads are too short. Moreover, it has to be
in a matrix compatible with the scanning arrangement and it has to have the
printed/embossed key labels that the application requires, else the entire thing
is TOTALLY useless. You've overlooked the fact that X and Y have values, and if
those values don't coincide with the ones on the original, the replacement won't
work. The KIM-1 keypad is not on a 4x4 or 4x5 matrix as most keypads of this
shape/size were prone to be.
Now, if you know of a suitable replacement for the KIM-1 keypad, which wears out
pretty easily, it would be very helpful to those who use the KIM-1 if you'd
share that information. A generalization about what could or might be (note
the subjunctive) won't be of help at all. Replacing KIM-1 keypads has been a
problem since the early '80's and I've never yet seen/heard of a direct
replacement.
>
> The biggest problem of the keypad is the materials didn't age well over
> time. Many still
> work well.
>
The only ones that still work well are the ones that haven't been opened. The
plastic doesn't keep well, apparently oxidizing along with the contacts and it
becomes brittle. I've never seen a KIM-1 that didn't have keypad problems, and
I haven't seen one up close since the early '80's. These were not made for many
years' use, but, rather, as a demo for the products MOS-Technology was promoting
at the time. The keypad was not of a type likely to last more than a few months
in occasional use, and if one wanted a durable keypad, the external connections
were prefectly suited for the attachment of a "decent" keypad. Unfortunately
the display was a mite small, and if one used an external keypad, it was highly
desirable to attach an external display, which was a mite more trouble, as well,
else seeing the display was a problem. Anyone old enough to have owned or used
a KIM-1 when they were in vogue would certainly recognize that today. (My mom
told me to quit that, else I'd go blind ... did I listen? ... I said I'd quit
when I needed glasses ... well ...)
>
> Allison
>
>
Received on Sun Apr 15 2001 - 13:31:15 BST