From: davidsen@ariel.crd.GE.COM (william E Davidsen) Subject: Re: Floppies (was Re: File sy Date: 14 Jul 1992 14:19:11 GMT
In article <711048281.F00051@remote.halcyon.com>, Thomas.Mcwilliams@f42.n377.z1.fidonet.org (Thomas Mcwilliams) writes:
|> Ordinary capacity:
|>
|> (512 bytes)(18 sectors)(80 tracks)(2 sides) = 1,474,560 bytes/disk
|>
|> High capacity:
|>
|> (512 bytes)(20 sectors)(84 tracks)(2 sides) = 1,720,320 bytes/disk
|>
|> However, there is no gaurantee that a drive will support 84 tracks.
|> All theoretically should support 20 sectors.
The 84 tracks is definitely doing something beyond spec, and the 20
sectors is about marginal on interrecord gap. You would be a lot better
off going to ten sectors of 1k and keeping the gap a little bigger. This
requires a smart device driver to buffer the data, but we did this in
CP/M in 1978, so it should be within reach for UNIX...
If you want decent performance, you really should go to cylinder
buffering (no I didn't mean track buffering).
--
bill davidsen, GE Corp. R&D Center; Box 8; Schenectady NY 12345
It never ceases to amaze me that otherwise rational people, able to
understand calculus, compound interest, and the income tax form, can
continue to believe that poker is a game of chance.