Re: Where did CKD disks come from?

According to Lynn Wheeler  <lynn@garlic.com>:

>
John Levine <johnl@taugh.com> writes:

My question is where did CKD come from? I looked at the 1964 IBM Systems Journal
issue that describes the design of S/360 which has an article describing the way
the channels work, but nothing about the disks. Wikipedia has a long list of CKD
drives and controllers but no hint of whose idea it was.
>
One clear mistake is that they underestimated how quickly main memories would
grow, which meant that you could cache keys in memory so most of what would
otherwise be found by a channel ISAM search was in the cached keys and you could
usually directly read correct record on the disk. Similarly, if you have
plenty of memory to buffer multiple disk blocks, splitting logical records of
whatever size across fixed size blocks is no big deal.

>
>
big part of CKD was trade-off of I/O and memory. search & multi-track
search ... have the I/O channel program search for the record you wanted
... at least by the mid-70s, the trade-off was inverting.
[ long example of terrible CKD performance ]

Any idea who invented CKD?  The Pugh et al history book says a lot about
disk hardware but nothing about software or CKD.  Someone must have invented
it but who?  When?

--
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John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
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