idea for a universal disk interface

Fred Cisin cisin at xenosoft.com
Fri Apr 15 17:54:13 CDT 2022


On Thu, 14 Apr 2022, Tom Gardner via cctalk wrote:
> This was the approach IBM used in it's first RAMAC RAID where I think 
> they had to buffer a whole cylinder but that was many generations ago

(my copy of the specs may not be exact):
Buffering a whole cylinder, or a whole surface, of the RAMAC was no 
big deal.
One hundred surfaces (52 platters, but not using bottom of bottommost nor 
top of topmost) totalling to 5 million 6 bit characters.

That's 50,000 characters per surface.
OR 50,000 characters per cylinder
("square geometry" :-)

100 tracks per side of a platter (at 20 tracks per inch) meant about 500 
characters per track

Problematic in the CP/M days, but such a buffer is small in current usage.


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