20 Dec
2024
20 Dec
'24
7:39 p.m.
On 2024-12-20 21:35, Chuck Guzis via cctalk wrote:
On 12/20/24 16:36, Van Snyder via cctalk wrote:
The chain with box drawing characters mention in the original post where
used to print the ALD. The 1403 had logic that limited the number of
hammers that could fire at once, there was a test routine that would
repeatedly fire the maximum number of hammers it was called the "Chain
Breaker Routine". The only drum printer I ever saw operating I think it
was a Honeywell printer and the person demoing it printed out some
pictures, the printer could fire most if not all hammers at once which
made quite a racket.
Paul.
The IBM 1403 printer had interchangeable print
chains. I know of only
four 1403 printers still working — two at the Computer History Museum
in Mountain View, CA, one at the IBM Technology Center in Böblingen,
Germany, and one near Endicott, NY.
All four have the 48-character "A" or "Business" chain, and CHM has
a
16-character numeric chain that allows the printer to run twice as fast
for numeric-only output. CHM doesn't have an "H" or "Fortran"
chain,
and as far as I know, none of the others do. The difference is that
parentheses are % and "lozenge" — a square with indented edges
— apostrophe is @, and = is # on the "A" chain. IBM also had a 64-
character chain that included box and line drawing graphics. BTW,
nobody seems to know what "lozenge" was meant to represent.
I recall
only learning once not to leave a cup of coffee atop a running
1403. I think the lozenge-character print train was mostly used on the
BCD machines like the 1401, but I could be mistaken.
I recall one of the old timers at CDC relating that try as they might,
they couldn't get a train printer of their own design without the print
train disintegrating. I believe that CDC quietly purchased a 1403 on
the gray market and took it to pieces. The result was the CDC 512. Up
until this time, the standard high-speed printer at CDC was the 501--a
drum printer.
It was interesting to note that hammer firing differences on a drum
printer resulted in characters being vertically displaced, which was
very annoying to the eye. Whereas the train printers could displace
characters horizontally and was not nearly as unsightly.
--Chuck