On Fri, 6 Jul 2001, John Honniball wrote:
> According to the "A few good men from Univac", the CDC
> Model 405 card reader was built for speed, and worked
> optically. It had a car headlamp bulb and a row of
> photodiodes. The card was read twice, and the results
> compared, any discrepancies sending the card to a "reject"
> bin.
Hmmmm. While not explicitly wanting to cast doubt on the credibility of
the book, ... Can anyone here confirm whether the book got those
particular facts right? From personal experience! NOT from some other
book that got its "facts" from this one!
1) At that time, automobile headlights were big, bulky, and inefficient.
Halogen bulbs were readily available, (for example, had come out for home
movie lighting), but were NOT available YET as automotive headlights.
Halogen automotive headlights became available later, but weren't legal
for several more decades. The automobile headlight was WAY too big to be
practical for that purpose, and the card reader would not have any need
for that much light. On the other hand, that was right when automobile
TAILlight bulbs reached their all time peak popularity for other uses,
such as the "Tensor" or "high intensity" domestic reading light that
consisted of a taillight bulb and a transformer. THAT would be a VERY
useful size for building into such equipment.
I USED TO have a chunk of surplus optics from a card reader (no idea
what make) that appeared to be based on a small light source. (such as a
halogen movie light bulb, or a TAILlight bulb)
2) Except for voting in Florida, would you want a card that failed to read
consistently to be REMOVED FROM SEQUENCE in the deck???!? Having the
computer produce an appropriate error message, and maybe even the offset
from the beginning of the file^H^H^H^H deck, would be the correct way to
handle it. In a purely data file, where the quantity of data doesn't much
matter, it could be OK. But there are too many situations where you would
NOT want to continue with the processing of the file if there are
corrupted records, and users would be IRATE to have the corrupted records
taken out of sequence! ("Hmmmm. Where in the program did this damaged
'N = N + 1' belong?")
--
Grumpy Ol' Fred cisin_at_xenosoft.com
Received on Fri Jul 06 2001 - 11:08:45 BST