26 Oct
2010
26 Oct
'10
8:05 p.m.
>> It looks to me like a punch card exactly fits
in there and the
>> contacts are what read the holes in the card.
> nope
> cards are read with 12 brushes
On Tue, 26 Oct 2010, Roger Holmes wrote:
Or 80 brushes, I think the holes in cards were made
tall and narrow to
make reading them that way easier.
"face down, nine edge first" (the way
Watson was buried)
or a matrix of 80 * 12
or a matrix of 40 * 12 (Wang clamshell port-a-punch reader)
My father (NOT a computer historian) used to tell me that IBM patented the
shape of the hole! That resulted in a few short-lived attempts at
round-hole cards, etc.),
and patented the "brush against brass roller". That resulted in a few
matrix readers, soon followed by CDC and others finally getting around to
making light-and-photocell readers, that so out-performed IBM's readers
that it significantly strengthened IBM's competitors.
--
Grumpy Ol' Fred cisin at xenosoft.com