rickb@tekig4.UUCP (Rick Bensene) (01/14/86)
Recently I acquired a 20Mb harddisk with the intent of upping the
capacity of my OS9 Level I system. The runs using an Adaptec ACB-4000
harddisk controller, with drivers that I wrote. The drivers are all
set up to address drives with greater than 65536 logical sectors, but
when I try to format the drive (which has 830 cylinders, 3 heads, and
33 sectors per track), it seems as if the upper byte of the three byte
logical sector number is assumed zero in RBF and IOMan. I've tried
all kinds of different format programs, and different versions of
RBF and IOMan, but to no avail. It seems that though OS9 Level One
has three bytes in which to pass logical sector numbers, only two
bytes are used in the kernal routines, meaning that a device cannot
have any more than 65536 sectors on it. This has the effect of allowing
me to use only 80% of the capacity of my new drive.
The question is: Does anyone out there know for sure if there is such
a limit to OS9 Level One's mass storage addressing, and if not, what's
going on here? I've heard rumors of such a limit in the past, but never
really heard solid evidence one way or another. I'm wondering if it's
an intentional limit set by Microware, with the third byte being reserved
for future use (in which case, it sure would have been nice to have
that written in the manuals somewhere), or if there's a bug in RBF or
IOMan. Any information would be appreciated.
Rick Bensene
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