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Another small tidbit: IBM standardized a terminal screen size of 80 columns because that was the same width as a standard format IBM punched card. In theory y
by cr0sh 8y ago
Another small tidbit:
IBM standardized a terminal screen size of 80 columns because that was the same width as a standard format IBM punched card.
In theory you could show two cards on one screen (height was 24 or 25 rows, usually) - but I honestly don't know if there was ever any call to show punched card data on a terminal, period...?
- stan_rogers 8y agoIn that sense, you could show many more than two cards on the screen at once, since each card is one row of characters. One 80-character line, one card. (There were no more than two holes per column on the card in order to avoid fold/tear lines as much as possible, so punch cards couldn't encode as much data as one might naïvely assume.)
- kens 8y agoTo clarify how punch cards worked: most of the characters in BCDIC/EBCDIC had one or two holes per column, but some had three. E.g. $ had three punches 11-8-3. In addition, you could use "column binary", where each column had arbitrary punches to hold 12 bits of data. Regarding the parent comment, there's no reason you'd display the hole pattern for two cards on an 80x24 display. The point is you'd use 80-column displays so each line represents the contents of a card.
- cr0sh 8y agoHey - thanks for explaining that to me; I was under a different impression of how it worked, and your explanation has really cleared things up. Now I know a bit more!