Hi!
13-Сен-2004 12:48 [EMAIL PROTECTED] (Luchezar Georgiev) wrote to
[EMAIL PROTECTED]:
>>> My AwardBIOS here for example does have such a feature. However, when I
>>> look at the boot record of my second hard drive, I see again boot drive
>>> = 80.
>> Do you try to boot from second drive with this boot record (which
>> contains 80h)? And it boots fine (without accessing first disk)?
LG> Yes, of course.
>>> So, BIOS probably swaps
LG> Not probably - surely.
Ie., second disk was enumerated as 80h (and, for example, partitions
from it was labeled earlier, than from first disk)?
>> "Probably"?! In this case it not need to pass to boot code information
>> about boot drive!
LG> The BIOS Boot specification
LG> (http://www.phoenix.com/resources/specs-bbs101.pdf) warns that only 0 and
LG> 80h can be safely considered as boot devices, albeit it recommends (but
LG> doesn't require) that BIOS passes boot device in DL on Int 19h. The 0/80h
LG> limitation
"warn" != "limitation". This warning may be only because authors of
tose spec may know about existance of buggy BIOSes.
LG> is due to the MS-DOS boot sectors, of course. So, whatever we
LG> decide, we should remove the FF kludge in any case. I already expressed my
LG> opinion - I agree with Jeremy and Eric that choice (2) is better for
LG> compatibility reasons.
No, not better. For example: if you use boot manager, which supports
loading boot record from second disk, then (your) boot code will not work in
such configurations, if it will contain 80h.
And vice versa: let suggest, that BIOS swaps disks numbers. In this
cases you can't boot (your) boot record, if it will contain 81h.
>> "Will"? Do you mean, that currend FD boot record (with FFh mask) doesn't
>> work when loading FD from second disk?!
LG> It works until replaced by another boot sector that tries to boot off
LG> drive FF.
?! Lucho, please, reread your sentence! We don't discuss _some_ _buggy_
boot code, which by some strange reason uses FFh as boot drive # (how this
relates to FD boot code?), we discuss, should _FD boot code_ expect drive#
from BIOS or use fixed values.
Hm. Or you mean, that _some_ (non-FD!) SYS, which writes own boot
sector, by some strange/buggy reason will preserve FD's boot record _field_
"drive number" (offset 0x24) and then its boot code will reuse this field?
How this alien buggy SYS relates to our boot code and dependence from BIOS
info?
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