Date   : Tue, 15 May 1990 16:15:05 GMT
From   : helios.ee.lbl.gov!hellgate.utah.edu!cc.utah.edu!cc.usu.edu!slsw2@ucsd.edu (Roger Ivie)
Subject: floppy drive hardware

In article <1721@mindlink.UUCP>, a577@mindlink.UUCP (Curt Sampson) writes:
> Apparently the Intel disk controller that IBM used in their original
machine is
> not reliable writing and reading 10 sectors per track.  So the started
out with
> 8, and then moved up to 9.  My Kaypro 4, using the Western Digital controller,
> reads/writes 10 sectors/track (400 K/disk) with no problems.

Actually, the problem is in the drive rather than the controller. With
10 sectors per track the drive has to be within 1/2 percent of the spec
rotational speed in order to reliably format a disk. DEC's RX50s (which
use 10 sectors per track) are only speced to 1 percent speed, so you cannot
always format diskettes in an RX50. This is why the Rainbow originally
shipped without a diskette formatter; having a format program did not
guarantee that you could actually format a diskette.

-- 
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Roger Ivie

35 S 300 W
Logan, Ut.  84321
(801) 752-8633
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