9 Jun
2006
9 Jun
'06
2:59 a.m.
Chuck Guzis wrote:
On 6/8/2006 at 12:40 PM Billy Pettit wrote:
We used some of them at Control Data on the Process
Control Computers. I
liked them; very nice, relieable drums, ran forever. I would love to find
one now. Would complement my old timer nicely.
They were also used in the Star-100
SBUs. For the life of me, I never
figured out why drums and not disks, but 'twas so. A lot of military
aircraft computers used them also. The givewaway there would be the 400 Hz
spindle motor. Cheers, Chuck
--------------------------------------------------------
Billy:
There were several reasons, but the biggest one was: they could do parallel
read and writes. You could stripe them for 16 bit wide data paths that
became incredibly fast. And with virtually no bit skew. Plus access time
was never more than one revolution. (It would be years before access time
on disks got down to the 16ms range.) Finally, we just hashed over the
painful reliability of early disks. Drums were used since the 50's, had a
lot engineering behind them.
Unfortunately, they were hard to increase capacity on, weren't removable and
never became cheap.
Billy