RLL driver

[Chip Rosenthal]

In article <739 at dekalb.UUCP> greg at dekalb.UUCP (Greg Philmon) writes:
>I'm in need of an RLL driver for XENIX.  If some kind soul could Email one it
>would be much appreciated.

I don't think you do.  You are talking apples and oranges here.  RLL is
a recording method, as is MFM.  The driver doesn't care about such details,
only what the interface to the controller looks like.  Most RLL controllers
present the common ST-506 interface.  The XENIX hard disk driver doesn't
care whether recording is by MFM, RLL, or punched holes, as long as the
interface is ST-506 compatible.

Assuming you are talking SCO XENIX, then the only thing you need to do
is verify that XENIX uses the right disk parameters (cylinders, tracks,
sectors, etc.)  Frequently, the disk geometry table in older BIOS ROM's
won't have an entry which exactly corresponds to your disk.  The most
common discrepancy is that you want to specify 26 sectors/track for RLL,
but the table only has 17 sectors/track entries for MFM disks.  In this
case, you need to select a disk type which is "close enuf".  This information
will only be used by the ROM bootstrap to read the disk partitioning table
and load the next stage of the bootstrap.  Once XENIX is running, it
ignores the disk type in the NOVRAM (/dev/cmos), and instead uses the
parameters you've selected.  You do this with the "dparam" command, which
is automatically run near the beginning of the installation procedure.
-- 
Chip Rosenthal / chip at vector.Dallas.TX.US / Dallas Semiconductor / 214-450-5337
Someday the whole country will be one big "Metroplex" - Zippy's friend Griffy