386 UNIX and FDISK

[Steve Neighorn]

In article <618 at cimcor.mn.org> mike at cimcor.mn.org (Michael Grenier) writes:
>Does anyone know if Microport 386 or other versions of AT&T UNIX
>for the 386 handle disk drives larger than 1024 tracks? I currently
>have Microport 286 version 2.4 and the fdisk command doesn't
>support my drive which has 1226 tracks.

AT&T Unix can have problems with disks that contain more than 1024
cylinders. This will be fixed in a Release 3.2 upgrade. For the time
being, you must set up the system with what is called "logical sector
translation." Here is an example of how it works using a Maxtor 4380
ESDI drive (1222 cylinders, 15 heads, 36 sectors/track), an Adaptec 
2322B controller, and AT&T Unix Release 3.2.

1) Install hard disk and controller in the machine. Set the Maxtor up
   for soft-sector operation.
2) Use setup to program the CMOS Drive Type for Type #1.
3) Boot a DOS disk.
4) load debug, and enter the command: g=c800:5
5) Choose selection 0 (format the drive) from the main menu.
6) Follow the instructions regarding bad sector mapping, and set the
   interleave for 1:1. When the format is done it will return to the
   main menu.
7) Choose selection 1 (DOS 3.3 style partition) from the main menu.
8) Partition the entire disk for partition #1. Return to the main menu.
9) Exit the BIOS formatting program.
10) Turn the machine off, take the Adaptec controller out and set the
    jumper that disables the controller's BIOS.
11) Use setup to program the CMOS Drive Type for a drive with the following
    parameters:

    Cylinders = 654
    Heads     =  16
    Sec/track =  63

    The trick here is getting the cylinder count under 1024 by increasing
    the other settings. You do lose a few hundred sectors with this technique.
    
    OLD: 1222x15x36 = 659880
    NEW:  654x16x63 = 659232

12) Boot your Unix disk and format as usual.

NOTES: Step 11 is the hard one for some machines, as not all 80386 machines
       have a BIOS that supports user definable drive types. 3.2 Unix will
       let you change the number of cylinders for a drive from within the
       installation program, but you must run "setup" to change the heads
       and sectors/track.

       The WD1007 gets around this limitation by providing user definable
       drive support in its own BIOS. (This is my understanding of the
       card - I don't have one myself).

       Unix 3.2 will appear to function, at least for awhile, if you
       ignore the above steps and just use the drive with 1222
       cylinders. But sometime during the installation of the system,
       perhaps the kernel rebuild with the 2K file system, the console
       will suddenly fill with BAD BLOCK remap messages. Then the
       dreaded BAD BLOCK IN UNIX SACRED AREA will appear. At that point
       you are in the unenviable position of being UPS (up shit creek).
       Yes, I tried this first, just to be sure :-(.

Good luck with your big disk!

-- 
Steven C. Neighorn            !tektronix!{psu-cs,reed,ogccse}!qiclab!neighorn
Intel Corporation            "Where we BUILD the Star Fighters that defend the
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