Remembering RAMAC

[Paul Koning]

>>>>> "der" == der Mouse <mouse at rodents.montreal.qc.ca> writes:

 >> Some disks had parallel heads too -- the CDC 6638 is 12 bits
 >> parallel.

 der> I'd even say that _most_ disks have parallel heads, though they
 der> generally throw away that parallelism.  (I don't know why; the
 der> most plausible reason that comes to mind is a "buh-but that's
 der> not how disks work" mindset.)

Maybe, but probably not.  More likely the answer is "it cost a lot (in
1970) to build N read/write channels rather than just one".  With
serial data, you just have one read/write channel, and someplace very
close to the heads you run that through a switch to connect to one of
N heads.  For parallel operation, you have to duplicate a lot of
logic.  Today that's just one chip, but not so in 1970...

	paul