Re: Will IBM 360 Floppies work in Apple ][ Drives?

[pausch@saaf.se (Paul Schlyter)]

In article <45dce030$0$20288$9b4e6d93@newsspool3.arcor-online.net>,
Linards Ticmanis  <ticmanis@gmx.de> wrote:

> David Empson wrote:
> 
>> I used the standard IBM 8" SSSD floppy disks on a CP/M system in the mid
>> 80s. If memory serves, it had 40 tracks, 32 sectors per track, 128 bytes
>> per sector, which would be 160 KB.
> 
> I seem to remember that it was 77 tracks of 26 sectors (or some other
> fairly odd numbers). Never had one, but CP/M has some built in tables
> for these. That's were those ugly 128 byte records come from that almost
> everybody else had to block/deblock in their BIOS, wasting precious space.
> 
> Just looked into wikipedia: it was really 77x26x128. Equivalent to 2002
> punch cards (2000 was a common box size for those, it seems).

Since 77*26 = 2002, this corresponds to 128 bytes per punch card.  But
wasn't the standard punch card 80 columns rather than 128 columns?
OK, each column had 12 punch locations instead of 8 - but if we
consider each punch location one but, that's still isn't enough for
128 bytes, only for 120 bytes.

The punched cards were used well before the computer age, actually as
early as 1725!  The IBM standard 80-column punch card originated in 1928.

   http://en.wikipedia.org/wiki/Punch_card

A punch card simulator can be found here:

   http://www.kloth.net/services/cardpunch.php

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