SCSI and 386/ix

Piercarlo Grandi pcg at
Tue Feb 6 06:07:11 AEST 1990

In article <1990Feb3.191842.1991 at ddsw1.MCS.COM> karl at ddsw1.MCS.COM (Karl Denninger) writes:

	[ ... about having dual WD1003 style controllers ... ]

   Even with ONE controller, it's not bad.  ISC >will< overlap seeks to the two
   devices, IF your controller can handle it.  If not, you have to turn off
   that feature in the space.c file for the device (it's on by default); this
   is the cause of some problmes with certain revisions of the WD1006 boards.

This perplexes me. You sure that a WD1003 style controller can
overlap seeks? Are there any that do? I can hardly imagine seeks
not being synchronous to the controller with a WD1003 style
controller, that must issue step pulses to the head.

Are there really any RLL or MFM controllers (the WD1006 is by
your implication) that can step independently the two arms?
Piercarlo "Peter" Grandi           | ARPA: at
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg at

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