20 Sep
2013
20 Sep
'13
3:54 p.m.
On 09/20/2013 01:52 PM, Fred Cisin wrote:
Our sources half a century were not authoritative, but
it made a
good story, with a moral of "don't be too brutal with the competition,
it will come back to byte you.".
Well, CDC was pretty good with vacuum capstans, which separated them
from IBM not only in the card, but also the tape
department. IBM used
pinch rollers in tape drives, but CDC used slotted
counter-rotating
air-bearing capstans. In the 405, pinch rollers were only used for
positive transport of the card being read through the photodiode array
(two columns; a card was actually read twice and the results compared;
vacuum capstans were used in the picker assembly.
There were additional photo-detectors near the top and bottom of the
card read station to correct for skew.
Cards were turned through two right angles after they were read, so the
stacker tray was parallel to the input hopper, with both mounted on a
shake table assembly. The unit was very noisy, particularly when
compared to something like an IBM 2501 reader, but the read speed was
evident just by the sound.
A screw-up in the stacker could lead to several succeeding cards being
"accordion pleated".
We just called them "cards". I suspect that if you were a university
professor, you called them "Hollerith cards" with a certain air of
superiority.
--Chuck