Hi you all,
Nestor Soriano <[EMAIL PROTECTED]> escreveuz...
> >So if we will make some fat16-formattingprogram, we will have to format in
> >MS-DOS 4 way.
>
> It is the best idea I think. "MS-DOS 4 way" means extra information in the
> boot sector:
>
> #20-#23: Number of sectors if it don't fits in 16 bits (else, this number
> is placed in #13 as in older versions)
> #24: Number of physical unit for HD (#80 is first)
> #25: Reserved (normally 0)
> #26: #29
> #27-#2A: Serial number
> #2B-#35: Disk name or NO NAME
> #36: FAT12 or FAT16 string
>
> The problem is that MSX-DOS puts a booting program starting in #20, so
> disks formatted in this way can't be used for boot.
No sweat!
Older disk format only fills parameters up to offset 1C-1Dh (=number
of reserved sectors), MSX bootsector routine starts at 1Eh, and the
above starts at 20h, which leaves 2 bytes (at 1E-1Fh), just enough to
put in a JR-instruction to a bit further on.
MSX-DOS2 formatted disks already do it that way...
Do note though, that on bootup, only one half of the bootsector
(offset 0-FFh, 256 bytes) is copied to C000h before C01Eh is called,
making it a bit difficult to use the other half for boot code.
Greetings,
Alwin Henseler ([EMAIL PROTECTED])
http://huizen.dds.nl/~alwinh/msx (MSX Tech Doc page)
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