Remembering RAMAC

[Paul Koning]

>>>>> "Allison" == Allison  <ajp166 at bellatlantic.net> writes:

 Allison> The big advantage and values of drums was high inerta plus
 Allison> parallel heads.  Some designs were 16bits wide (maybe there
 Allison> were wider) plus timing tracks. So while small ( I remember
 Allison> the 128kw swapping drum on the KA10s) they were extremely
 Allison> fast.

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

 Allison> Of course late in the game was the 32kW RS08 disk for the
 Allison> PDP8 systems.  Small but very fast word wide storage.

Not fast at all, because that one is NOT parallel -- the RS08 (and its
PDP11 successor RS64, as well as the RF11/RS11) are all serial fixed
head drives.  The doc says the RS08 takes 32 microseconds per (12 bit)
word; the RF11 was slightly faster at 15 microseconds per (16 bit)
word. 

      paul