[syslinux] syslinux-3.36 Physical Floppy Disk Access Problem

Desmond Boyd brokencode at hotmail.co.uk
Wed Jun 13 04:00:11 PDT 2007


>Desmond Boyd wrote:
> > As requested, I have tested the distributions listed below to try to 
>isolate
> > when physical disk drive access for me was lost, results are as follows:
> >
> > Physical Disk Drive B: OK with Virtual Disk Drive as A:
> > 3.20
> > 3.30
> > 3.31
> > 3.32 Pre1
> >
> > Physical Disk Drive B: Not Present only Virtual Disks A: and B:
> > 3.35
> > 3.35 Pre1
> > 3.35 Pre2
> > 3.35 Pre3
> > 3.35 Pre4
> > 3.35 Pre5
> > 3.36
> > 3.50
> >
>
>Could you also test the various 3.32-preX releases (2 to 8) to narrow
>down the failure further?
>
>The most likely failure seems to be between 3.32-pre3 and -pre4:
>
>     memdisk: Constrain input drive numbers both by equipment byte and
>     INT 13h
>
>     Apparently on some BIOSes, INT 13h return a bogus number of floppy
>     drives when the real value is zero (probably because the code
>     doesn't check the validity bit in the equipment byte.)  Do it
>     ourselves if we need to.
>
>There should be a line when MEMDISK boots up saying something about "INT
>13 08", what is that printout?
>
>	-hpa
>

Hi,

Version 3.32-pre3 Physical Disk Drive B: OK with Virtual Disk Drive as A:
Version 3.32-pre4 Physical Disk Drive B: Not Present only Virtual Disks A: 
and B:

INT 13 08 Success, Count = 1, BPT = f000:a137
old int13=f00023cb, int15=f000f859
new int13= 9ec00008, int15=9ec00375

All memory addresses listed on the memdisk info page @ bootup for pre3/pre4 
are identical but pre4 does not see the physical floppy disk.

If you need the exact screen information from both versions I can write each 
one down unless there is a way to save the boot information with a switch to 
the virtual fdd then I can upload the info to a networkshare.

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