IBM Mainframe Discussion List wrote:
The 2321 was only responsible for the bb part of the mbbcchhr. The m was,
and still is, the extent number in the DEB.
Bill Fairchild
Plainfield, IL
i.e. seek CCW has six byte length ... bbcchh
CKD DASD command codes ... from my q&d conversion of gcard ios3270 to html
(seek has count/length of "6"):
http://www.garlic.com/~lynn/gcard.html#26.1
pictures of 2321 here:
http://members.optushome.com.au/intaretro/2321DCD.htm
http://www.columbia.edu/acis/history/datacell.html
in the above you can see "bin" closeup ... "BB" selection could
rotate the whole cylinder to place correct "bin" under the
read/write heads ... rotation somewhat would reminded me of
washing machine.
past posts mentioning 2321 in this thread:
http://www.garlic.com/~lynn/2007e.html#51 FBA rant
http://www.garlic.com/~lynn/2007e.html#63 FBA rant
there is some slight physical packaging resemblance between 2321 and 2301 drum
... both
appearing to be cylinders. 2301 drum can be seen here in mid-background to the
right
of the tape-drives.
http://www.columbia.edu/acis/history/2311.html
another system picture with 2301 in mid-background
http://www.cs.ncl.ac.uk/events/anniversaries/40th/images/ibm360_672/29.jpg
close-up here
http://www.columbia.edu/acis/history/drum.html
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