[comp.unix.microport] Unix, drive-types & Rom

john@wa3wbu.UUCP (John Gayman) (02/03/89)

    How does Unix such as Microport handle hard disks that aren't listed
  in the Rom disk table ?  Is it possible to utilize a drive for which
  you have no Rom listing assuming you know all its parameters ?


						John


-- 
John Gayman, WA3WBU              |           UUCP: uunet!wa3wbu!john
1869 Valley Rd.                  |           ARPA: john@wa3wbu.uu.net 
Marysville, PA 17053             |           Packet: WA3WBU @ AK3P 

ken@uport.UUCP (Ken Chapin) (02/05/89)

In article <222@wa3wbu.UUCP> john@wa3wbu.UUCP (John Gayman) writes:
>
>    How does Unix such as Microport handle hard disks that aren't listed
>  in the Rom disk table ?  Is it possible to utilize a drive for which
>  you have no Rom listing assuming you know all its parameters ?
>

We first look into CMOS to see what is configured. If the installer says that 
geometry of the drive is different from what CMOS says, we write out the new
geometry in the pdinfo block (see /usr/include/sys/vtoc.h) that sits on a 
reserved location of the disk. That reserved location is by the way on the first
sector of the second track of the drive. By putting the pdinfo table there, you
don't have to know the exact geometry of the drive before you write (like know-
ing the number of sectors per track). You just have to assume that the drive has
got at least two tracks.

Ken Chapin         UUCP: ...!{sun | ucbvax | ihnp4}!amdcad!uport!ken
Microport Systems
Technical Support         

" Maynard) (02/06/89)

In article <222@wa3wbu.UUCP> john@wa3wbu.UUCP (John Gayman) writes:
>    How does Unix such as Microport handle hard disks that aren't listed
>  in the Rom disk table ?  Is it possible to utilize a drive for which
>  you have no Rom listing assuming you know all its parameters ?

Neither of my disk drives (a Maxtor 1120 and a Seagate ST251) are listed
exactly in my ROM table.
What I did was to setup a disk type number that had the same number of
heads and fewer cylinders, then use Microport's fdisk to tell it the
real parameters. Microport's fdisk writes the real drive parameters in
an unused area of the partition table, and refers to them exclusively.
THe only reason to have the drive type in ROM is so that the power-on
self test will work as expected, and it doesn't care if it can get to
all the disk or not.
If you want a DOS partition on the same drive, use Microport's fdisk to
set it up, and make it the first partition on the drive (starting at
cylinder 1).

-- 
Jay Maynard, EMT-P, K5ZC, PP-ASEL   | Never ascribe to malice that which can
uucp:        uunet!nuchat!   (eieio)| adequately be explained by stupidity.
    hoptoad!academ!uhnix1!splut!jay +----------------------------------------
{killer,bellcore}!texbell!          | "Sexism is ugly." - Cheryl Stewart