Yes, 40:8f might be wrong in VirtualBox and yes the
person who set it to the wrong value may even be in
your "BIOS Central" style group of 40:8f users. But
for example the IBM PS/2 and PC Technical Reference
(official 1991 IBM docs) clearly describes 40:8f as
RESERVED byte in the BIOS Data Area chapter, so you
are still walking on thin ice with UIDE.  Of course
the same reference book also describes ints 13.15 &
13.16 when it comes to proper floppy change checks.

Again, using int 13 instead of 40:xx would have
avoided all UIDE troubles - even on VirtualBox.

Another interesting thing is that the VirtualBox
PCI BIOS seems to scan all possible 256 PCI bus
numbers while it also states that it only has one
such bus at the moment. MAX_BUSDEVFN could thus
be lowered to 100h instead of 10000h which could
mean 256 times faster UIDE load times. If this
is true, PCISLEEP style PCI bus scans would be
even faster (up to 8 times) compared to even the
possible 256-fold improvement through VirtualBox
BIOS tweaking, compared to 3 minutes in UIDE-VB.

Of course it would be interesting to contact some
VirtualBox experts about whether MAX_BUSDEVFN is
indeed too high (PS: pcibios.inc and pcibio32.asm
should probably derive the CL returned by int 1a
function b101 from MAX_BUSDEVFN for consistency)
and about whether orgs.asm line 1137 & 1147 CODE
should be changed, to reflect the missing change-
line support, or whether only the COMMENT should
be changed if this bit is about 80 track support
rather than change line support!


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