I took a second look and here are the keys that were
'locked':
Set Up
Break
Del
Line INS Char
Line DEL Char
Scrn CLR Line
INS Repl
Escape
Home
All the Arrow keys, up, down, right, left
It's a standard ASCII Wyse Keyboard
Doug
On 3/10/2024 6:10 PM, Dennis Boone via cctalk wrote:
I
thought, at first, some dirt or debris had gotten stuck there, but
on closer look I saw something black below the keys that seemed to be
stuck. I pulled a key cap off and found a U shaped piece of black
plastic that was put there on purpose to prevent you from depressing
the key.
The question came to mind; "What sort of
application would be so
crude that you would have to prevent the user from depressing certain
keys?"
I saw this in at least two applications:
1. The Service Merchandise chain
(
https://en.wikipedia.org/wiki/Service_Merchandise) used serial
terminals for their in-showroom catalog ordering. Some keys were
blocked somehow, though I never peeled up key caps to see how. :)
I want to say that backspace was one of the blocked keys, the
aggravation of which is probably why I remember this.
2. CLSI library systems (LIBS100 on PDP-11). Ours here had ADM-3A
(iirc) terminals with the break key blocked, iirc, though there were
plenty of other ways to discombobulate the thing inadvertently. It was
also available via dialup from keyboards that were not so modified.
I once heated up a paper clip to read hot and shoved it through the stem
of a TVI-925's SEND key, which was used for block mode functions, and
caused the terminal to vomit screen contents back to the host. Unwanted
presses of course produced a heck of a mess. (Older versions of our
application ran in block mode, but you could always hit ESC-S to send
the screen, and it was unfortunately easy, at least for me, to thwack
SEND by mistake.)
De