At 18 12 04, 01:04 PM, Bill Potts wrote:
>First, please note that your message contains some sequences (e.g., &#8111
>and &#8212, presumably intended to be left and right typographical quotes 
>respectively -- not supported in text mode) that badly affect readability.

Sorry about that -- I used a wordprocessor, but used a generic "paste" rather 
than "paste unformatted" as I normally do.

>The maximum theoretical capacity of an 80-column punch card is actually 120
>bytes (12 hole positions per column). However, not too many computers were
>equipped to read cards in binary mode and there was no data entry equipment
>(e.g., keypunches) that could punch them in that mode (nor would it have
>been practical to do so). In practice, each column contained less
>information than today's byte. Rather, it contained only as much information
>as a 6-bit character.

You certainly remember punch cards better than I do, but your 6-bit character 
does not make sense to me. 2^6 is 64, but the alphabet (upper & lower case) 
plus 10 digits is 62 different characters, not counting punctuation. If memory 
serves, the cards DID support both upper and lower case, plus a variety of 
punctuation symbols.

What am I missing here?

Jim Elwell

 

Jim Elwell, CAMS
Electrical Engineer
Industrial manufacturing manager
Salt Lake City, Utah, USA
www.qsicorp.com

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