3 Jul
2001
3 Jul
'01
2:51 p.m.
On Tue, 3 Jul 2001, Jerome Fine wrote:
If a mechanical reader example is one that has a plate
with 960 copper plated
raised areas over which the card was placed, then I would also need to know
how the optical mechanism functions. From what I remembered of the high
speed card readers, they usually fed the card into a slot around a curved
read area where I presume the light shone through. I would think that for the
light reader mechanism, timing would be critical.
What I learned in school 35 years ago:
Long ago, IBM patented the shape of the hole, and a few companies
attempted to build machines with round holes! But THAT is not the
issue. That patent was overturned.
Then, in their ongoing efforts to mistreat the competition, IBM patented
their brass roller. The IBM card reading system consisted of a brass
roller and a group of metal brushes. Which brush made contact was one
axis, and the rotational position of the roller was the other axis. IBM's
actions backfired. They ALMOST worked - several competitors almost went
under when they could no longer use a brass roller. Bizarre, stupid
things were tried, such as 960 plungers in a grid. Then one company
(CDC?) succeeded in what had previously been too great an engineering
challenge, and came out with an optical reader (12 photocells and a
roller). In addition to getting around the IBM patent, they also ended up
with a card reader that could be made to run much faster than the fastest
that IBM had to offer; thus bringing them back from the brink and into the
lead.
Tolerance issue? Sorry, I have no idea as to the
requirements, but I often
found that the first attempt to add a character with an 029 resulted in a misplaced
punch for just the added character - so a duplicate and a second attempt
FIX THAT PUNCH!
I have never had that problem with a properly aligned 029. But they DO
need to be aligned and adjusted occasionally.
--
Grumpy Ol' Fred cisin(a)xenosoft.com