386 UNIX and FDISK

[Joel Clark]

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.

Procedure to access > 1024 tracks.  The 63 sector translation method.
on AT&T UNIX Sys V R3.1 or R3.2 as released by iNTEL  (or Bell Tech.)

I have never done this, but it has been done twice here by some other
engineers.  They never read this newsgroup so I will try to explain what they
have done.  This is also cryptically explained on the last 3 pages of the
"Adaptec ACB-2320/ACB-2322 User's Manual".  See also page 31 (General
Translation Mode) of the "WD1007A-WAH/WA2 Winchester/Floppy Disk
Controller" manual Document #79-000261 From Wester Digital.

You need a controller with low-level formatting BIOS.  We have used the
Adaptec 2322-B16 and the Western Digital 1007WA2-001

You need to use the formula:  
  Logical cylinders = Phys heads * Phys Sect PT. * Phys Cyl / 63 * 16

	Western Digital's formula is slightly different and explained
	in detail on pages 31 and 32 of their manual (see above reference).

You need motherboard BIOS that has or can create a drive type entry for
a disk with Logical number of cylinders, 16 heads, and 63 SPT

For example if you have a disk with 1224 cylinders, 15 heads, and 36 Sectors
Per Track, and you format this with the Adaptec low-level format you will
actually have 1222 cylinders, 15 heads, and 36 SPT available.  (2 are saved
for bad sectors)   Plug these into the formula you get:
654 = (15 * 36 * 1222)/ (63 * 16)
So you need a motherboard BIOS drive type entry for a disk with 654 cylinders,
16 heads, and 63 SPT.

Now execute the following steps:

1)  Boot DOS and run the controller format routine:
	A>  DEBUG
	-   g=C800:5

	For Adaptec pick '0' to primary format the drive.  format will inform
	you it is formatting a 1222 cylinder disk.  Continue.

	For WD we were using Drive type 1 in the motherboard BIOS.
	This specified 618 cylinders 16 heads and 63 SPT.  So we
	hit '+' until a disk type matching our logical cylinders etc.
	was shown.  Continue with format.

	Enter Defect information.

2)  For the Adaptec controller when formatting has completed, shutdown the
machine and disable the Adaptec BIOS by removing the BIOS enable jumper from
the controller.

3)  Reset the processor and run setup to pick or create the appropriate 
drive type (based on the logical cylinders, heads, and SPT)

4)  Insert the UNIX boot floppy and reset the system.  Install the UNIX
software but DO NOT REFORMAT THE DISK.



WARNING: CHANCES ARE AT BEST 50/50 THAT YOU WILL THE RIGHT MOTHERBOARD,
	 AND BIOS ON THE MOTHERBOARD AND CONTROLLER CARD TO ALLOW THIS
	 TO SUCCEED.

To do this on a WD controller on R3.0 UNIX we had to mod our motherboard.
To do this on an Adaptec Controller 2322-B16 we had to get new controller
firmware.

Best of Luck

Joel Clark
iNTEL Scientific Computers			joel at intelisc.intel.com
Beaverton, OR	(503) 629-7732		{tektronix}!ogccsu!intelisc!joel