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65 lines
2.4 KiB
NASM
65 lines
2.4 KiB
NASM
6 years ago
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org 0x7C00
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%define SECTOR_AMOUNT 0x10 ;Precompiler defined value for easy changing
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jmp short start
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nop
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; BPB
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OEMLabel db "Example " ; Disk label
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BytesPerSector dw 512 ; Bytes per sector
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SectorsPerCluster db 1 ; Sectors per cluster
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ReservedForBoot dw 1 ; Reserved sectors for boot record
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NumberOfFats db 2 ; Number of copies of the FAT
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RootDirEntries dw 224 ; Number of entries in root dir
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LogicalSectors dw 2880 ; Number of logical sectors
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MediumByte db 0F0h ; Medium descriptor byte
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SectorsPerFat dw 9 ; Sectors per FAT
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SectorsPerTrack dw 18 ; Sectors per track (36/cylinder)
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Sides dw 2 ; Number of sides/heads
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HiddenSectors dd 0 ; Number of hidden sectors
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LargeSectors dd 0 ; Number of LBA sectors
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DriveNo dw 0 ; Drive No: 0
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Signature db 41 ; Drive signature: 41 for floppy
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VolumeID dd 00000000h ; Volume ID: any number
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VolumeLabel db "Example "; Volume Label: any 11 chars
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FileSystem db "FAT12 " ; File system type: don't change!
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start:
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; ------------------------------------------------------------------
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;Reset disk system
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mov ah, 0
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int 0x13 ; 0x13 ah=0 dl = drive number
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jc errorpart
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;Read from harddrive and write to RAM
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mov bx, 0x8000 ; bx = address to write the kernel to
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mov al, SECTOR_AMOUNT ; al = amount of sectors to read
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mov ch, 0 ; cylinder/track = 0
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mov dh, 0 ; head = 0
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mov cl, 2 ; sector = 2
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mov ah, 2 ; ah = 2: read from drive
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int 0x13 ; => ah = status, al = amount read
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jc errorpart
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jmp 0x8000
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errorpart: ;if stuff went wrong you end here so let's display a message
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mov si, errormsg
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mov bh, 0x00 ;page 0
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mov bl, 0x07 ;text attribute
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mov ah, 0x0E ;tells BIOS to print char
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.part:
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lodsb
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sub al, 0
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jz end
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int 0x10 ;interrupt
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jmp .part
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end:
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jmp $
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errormsg db "Failed to load...",0
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times 510-($-$$) db 0
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;Begin MBR Signature
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db 0x55 ;byte 511 = 0x55
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db 0xAA ;byte 512 = 0xAA
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