Whence 556?

Shoppa, Tim tshoppa at wmata.com
Sun Jun 3 12:34:37 CDT 2018


The 729 CE manual quotes 555 BPI. I’m not sure when it became 556. http://bitsavers.trailing-edge.com/pdf/ibm/magtape/729/223-6845_729_CEman_1959.pdf

The IBM 728 was 248 BPI. Before that it was the nice round number 200 BPI.

I tried permutations of standard IPS and round number data rates and don’t see anything that yields exactly 556BPI.

Tim


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