boot_fd.asm

nucleus_arm.rar

[BITS 16]
[ORG 0x7C00]

jmp Entry
nop
     
     OEM_ID                db "NUCLEUS0"
     BytesPerSector        dw 0x0200
     SectorsPerCluster     db 0x01
     ReservedSectors       dw 0x0001
     TotalFATs             db 0x02
     MaxRootEntries        dw 0x00E0
     TotalSectorsSmall     dw 0x0B40
     MediaDescriptor       db 0xF0
     SectorsPerFAT         dw 0x0009
     SectorsPerTrack       dw 0x0012
     NumHeads              dw 0x0002
     HiddenSectors         dd 0x00000000
     TotalSectorsLarge     dd 0x00000000
     DriveNumber           db 0x00
     Flags                 db 0x00
     Signature             db 0x29
     VolumeID              dd 0xC001D00D
     VolumeLabel           db "NUCLEUSBOOT"
     SystemID              db "FAT12   "

Entry:
     ; code located at 0000:7C00, adjust segment registers
	jmp 0x0000:_Start

_Start:
          cli
          mov     ax, cs
          mov     ds, ax
          mov     es, ax
          mov     fs, ax
          mov     gs, ax
          mov     [DriveNumber],dl		; Use drive number passed from BIOS
     ; create stack
          mov     ss, ax
          mov     sp, 0xFFF8
          sti
     ; post message
          mov     si, msgLoading
          call    DisplayMessage
LOAD_ROOT:
     ; compute size of root directory and store in 慶x