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Amateur OS Sector layout
contains the sector layout for Amateur OS
on the boot floppy. To make things
easier, I'm going
to use a 2 stage boot. The boot
sector code will check
the machine and load the second
stage from sectors
marked used in the FAT. The second
stage will then
find the kernel and continue loading.
HEAD 0 TRACK 0 SECTOR 1
a regular bootstrap. It will do the following:
HEAD 0 TRACK 0 SECTOR 2
Set the BPB
Load the banner from disk to video memory
Test for 486
Set the A20 line
Load second stage boot into memory
Jump to second stage
the location for the modified FAT table.
The first three sectors have been
marked used. This
cause DOS to start the first file
above the second
stage loader and the banner code.
Complete July 4, 2001
HEAD 1 TRACK 0 SECTOR 16
bytes is for the banner. 512 bytes is
enough for 3 lines in text mode.
The banner was made
in QuickBasic 4.5 and bsaveed
to a file. The bsave
header was stripped off and the
file padded to 512.
Complete July 1, 2001
HEAD 1 TRACK 0 SECTOR 17, 18
two sectors are for the second stage loader.
It will do the following:
A normal boot sector can do all this
in 512 bytes. 1K
Setup Real Flat mode (??)
Load boot sector
Calculate location of directory
Load directory into memory
Scan directory for kernel file name
Locate and load all parts of the kernel into memory
Jump to kernel
should give a little elbow room.
eye on the log page
for posting of the code.
If you have a comment or question,
please feel free
to send me an Email.