30 lines
2.3 KiB
NASM
30 lines
2.3 KiB
NASM
; ------------------------------------------
|
|
; This will be where the floppy FAT12 header
|
|
; Bytes 3-61
|
|
; https://technet.microsoft.com/en-us/library/cc976796.aspx
|
|
; Values are those used by IBM for 1.44 MB, 3.5" diskette
|
|
; ------------------------------------------
|
|
|
|
OEM_name db "DeanOS " ; Bytes 03-10 - OEM name (Original Equipment Manufacturer) The name for the bootloader/OS
|
|
Bytes_per_sector dw 512 ; Bytes 11-12 - Number of bytes per sector (usually 512 bytes)
|
|
Sectors_per_cluster db 1 ; Bytes 13 - Number of sectors per cluster, is 1 because in FAT12 a cluster is the same as a sector
|
|
Reserved_sectors dw 1 ; Bytes 14-15 - For FAT12 is 1
|
|
FAT_tables db 2 ; Bytes 16 - Number of FAT tables (usually 2)
|
|
Root_directory_size dw 224 ; Bytes 17-18 - Size of root directory entries 224 for FAT12
|
|
Sectors_in_filesystem dw 2880 ; Bytes 19-20 - Total number of sectors in the file system (usually 2880)
|
|
Media_descriptor_type db 0xF0 ; Bytes 21 - Media descriptor: 3.5" floppy 1440KB
|
|
Sectors_per_FAT dw 9 ; Bytes 22-23 - Number of sectors per FAT is 9
|
|
Sectors_per_track dw 18 ; Bytes 24-25 - Number of sectors per track is 12 but found to be 9
|
|
Head_count dw 2 ; Bytes 26-27 - Number of heads/sides of the floppy (usually 2)
|
|
Hidden_sectors dd 0 ; Bytes 28-31 - Number of hidden sectors (usually 0)
|
|
Total_sectors dd 0 ; Bytes 32-35 - Total number of sectors in file system
|
|
Logical_drive_number db 0 ; Bytes 36 - Logical drive number (0)
|
|
Reserved db 0 ; Bytes 37 - Reserved sectors
|
|
Extended_signature db 0x29 ; Bytes 38 - Indicates that there 3 more fields
|
|
Serial_number dd 0xA1B2C3D4 ; Bytes 39-42 - Serial number, can be anything
|
|
Volume_lable db "OS bootdisk" ; Bytes 43-53 - Name of the volume, 11 characters
|
|
Filesystem_type db "FAT12 " ; Bytes 54-61 - File system type (FAT12), 8 characters
|
|
|
|
; ------------------------------------------
|
|
; End of FAT12 header
|
|
; ------------------------------------------
|