XENIX 2.2.3 and >1024 h.d. cylinders: possible?

[Karl Denninger]

In article <13569 at well.UUCP> whofan at well.UUCP (Brian Lawrence Dear) writes:
>
>Well, we finally got a second hard disk for our AST Premium/386 20mHz
>machine.  We got a CDC WREN V, 1224 cylinders, 15 heads.  Now,
>we got it up and running, and fdisk says it's got 308000 blocks, or about
>317 megabytes, which is right, but the XENIX kernel or something will
>only let us get at the first 1024 cylinders (indeed, if that many). 
>When I do a "df -v" the drive says it has 198000 blocks total.  Or a little
>over 200MB.  We need the whole thing, and we need it bad.
>
>I can't believe version 2.2.3 can't support big hard disk drives.  I called
>SCO Support today and got a suggestion that I play with DOS DEBUG and 
>fiddle with the WD1007-WAH ESDI controller chip that's on AST's disk
>controller card.  I said, what do I type into DEBUG, like what address, etc?
>He said he didn't know.  So I am kinda stuck.

Well, you have two choices:

o)	Change the jumpers on the controller so that it remaps the drive
	type to something that has < 1024 cylinders and 63 sectors per
	track.  This is supported by the WD1007 controller.  You should not
	have to reformat for this, although you will need to play
	(CAREFULLY) with the "dkinit" program.  Make a floppy boot and root
	diskette before you mess with this!  The geometry change itself is
	done through debug with "G=c800:5" from MSDOS.  I am not certain
	whether messing with this will wipe the disk contents however -- I'd
	make a backup first to be sure.

	Whether AST's "funny" board can handle this is another matter.  If you
	get really stuck you can toss the AST board and get a regular
	WD1007-WA2, those work great.

o)	Upgrade to 2.3.2, which will handle a drive with > 1024 cylinders.
	It is not necessary to go all the way to SCO Unix, although I guess
	you could do that as well.

--
Karl Denninger (karl at ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
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