20 Sep
2013
20 Sep
'13
11:40 a.m.
On 20/09/2013 19:24, Jonathan Katz wrote:
All,
Thank you for your generous donations to the STEM program I'm working
on. I have a question or two about the punch cards I've received.
Some of the cards have printing on one side, and are "dog eared" or
have the angled corner on one end.
Other cards have the printing reversed; the dog-ear corner is on the
other end of the card when I'm looking at the printing.
You always look at a card from the printed side. Data is stored in
columns and generally used "left to right" , in the same way that we
read "latin" text...
Many computers read them that way as well, but some readers move the
card along the other axis, and so read a row of holes at a time....
If those cards with the reversed "cut
corner" or "dogear" were used in
the same machine as the first set of cards, they'd be read
"backwards." ... so why the two different formats?
No you always read from the printed size. I think the different corners
allowed you to easily separate decks. So you might use those with the
left corner trimmed for JCL and those with the right corner for data
cards. Then they were easily separated after the run. Were I worked we
also used different colours. So when we had card master files you read
the green cards and punched blue one week, then the next read the blue
and punched red, and lastly read the red and punched green so we always
had three generations of data...
Dave
G4UGM