24 Mar
2016
24 Mar
'16
4:46 a.m.
On Mon, 21 Mar 2016, scj(a)yaccman.com wrote:
Actually, a Magic Marker drawing a diagonal stripe
down the top of the
cards worked almost as well, and didn't require repunching the deck with
every change...
Yep, an old trick. Trouble is, whenever I rearranged the cards I had to
use another colour, and then had to remember which...
Hmm. I recall walking into the computing center to
see an amazing
cascade of cards arcing 20 feet across the room. The operator hadn't
set up the card reader correctly.... Panic ensued...
I've seen something like that; it involved a high-speed CDC reader/punch,
as I recall. Cards everywhere :-) Seems that the deck wasn't
straightened before inserting by the trainee operator. Pity the poor
user.
In another case, I had written a FORTRAN program that
produced a page
header on the printer with a page number. The first time I tried to
print 200 pages, when I hit 100 the printer decided that I wanted one
line per page! The printer was not a happy camper. Neither were the
operators.
Have you any idea how fast the IBM 1403 printer can slew blank pages?
Cough cough... It chewed through a box in an instant, and I got to
re-pack it afterwards. You also learned to not place your coffee cup on
it (I was doing the midnight shift at the time), because when it ran out
of paper then the door would open automatically...
I think it was because of an undefined format control character, and the
printer's control tape went hunting for it.
But the closest I came to being murdered was when I
submitted a job
before lunch, and the sign said the turnaround time was an hour. When I
got back, the job was not done, and the wait was 2 hours. Each hour,
the wait grew by an hour. At about 4:30, four extremely angry operators
and managers came into my office with murder in their eyes and accused
me of trying to "be funny" (sic) with the computer. I had no idea what
they were talking about. It turns out that the operating system had
been upgraded, so that it automatically started pending jobs when it
came up after a crash. It also turned out that I had made a common
FORTRAN error--I had "called" a labeled common region instead of a
similarly-named function. And it turned out that the first data value
was a -.25 floating-point value. And it also turned out that the
computer's idea of instruction decode was to pick up the first few bits
of the word and use it as an index into the microcode. And it also
turned out that when -.25 was so "executed", it took the CPU into the
power down sequence, and it turned the machine off! And, thanks to the
software upgrade, when they rebooted, it turned itself off again. And
again... I was happy to escape with my skin...
Closest I've ever been murdered was when I "accidentally" filled the local
11/70 with an uninterruptible instruction sequence. And who here hasn't
"tried out" that self-reproducing program? The only way to recover was to
switch it off, as the HALT key was implemented as an interrupt, and guess
what it wasn't doing at the time?
Try writing a self-reproducing program some time i.e. one that creates an
exact copy of itself; it's an exercise in computer science, and is not as
easy as it sounds.
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will
suffer."