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wengyin777wengyin777
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6 files changed

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6 files changed

+386
-0
lines changed

‎BestsoftOS.flp

1.41 MB
Binary file not shown.

‎BestsoftOS.iso

1.76 MB
Binary file not shown.

‎bootloader.asm

Lines changed: 321 additions & 0 deletions
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BITS 16
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jmp short bootloader_start
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nop
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OEMLabel db "BESTSOFT"
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BytesPerSector dw 512
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SectorsPerCluster db 1
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ReservedForBoot dw 1
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NumberOfFats db 2
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RootDirEntries dw 224
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LogicalSectors dw 2880
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MediumByte db 0F0h
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SectorsPerFat dw 9
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SectorsPerTrack dw 18
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Sides dw 2
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HiddenSectors dd 0
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LargeSectors dd 0
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DriveNo dw 0
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Signature db 41
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VolumeID dd 00000000h
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VolumeLabel db " "
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FileSystem db "FAT12 "
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bootloader_start:
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mov ax, 07C0h ; Set up 4K of stack space above buffer
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add ax, 544 ; 8k buffer = 512 paragraphs + 32 paragraphs (loader)
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cli ; Disable interrupts while changing stack
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mov ss, ax
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mov sp, 4096
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sti ; Restore interrupts
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mov ax, 07C0h ; Set data segment to where we are loaded
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mov ds, ax
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; NOTE: A few early BIOSes are reported to improperly set DL
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cmp dl, 0
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je no_change
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mov [bootdev], dl ; Save boot device number
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mov ah, 8 ; Get drive parameters
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int 13h
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jc fatal_disk_error
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and cx, 3Fh ; Maximum sector number
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mov [SectorsPerTrack], cx ; Sector numbers start at 1
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movzx dx, dh ; Maximum head number
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add dx, 1 ; Head numbers start at 0 - add 1 for total
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mov [Sides], dx
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no_change:
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mov eax, 0 ; Needed for some older BIOSes
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floppy_ok:
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mov ax, 19
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call l2hts
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mov si, buffer
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mov bx, ds
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mov es, bx
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mov bx, si
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mov ah, 2
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mov al, 14
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pusha
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read_root_dir:
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popa
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pusha
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stc
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int 13h
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jnc search_dir
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call reset_floppy
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jnc read_root_dir
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jmp reboot
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search_dir:
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popa
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mov ax, ds
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mov es, ax
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mov di, buffer
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mov cx, word [RootDirEntries]
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mov ax, 0
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next_root_entry:
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xchg cx, dx
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mov si, kern_filename
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mov cx, 11
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rep cmpsb
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je found_file_to_load
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add ax, 32
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mov di, buffer
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add di, ax
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xchg dx, cx
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loop next_root_entry
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mov si, file_not_found
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call print_string
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jmp reboot
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found_file_to_load:
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mov ax, word [es:di+0Fh]
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mov word [cluster], ax
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mov ax, 1
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call l2hts
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mov di, buffer
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mov bx, di
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mov ah, 2
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mov al, 9
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pusha
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read_fat:
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popa
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pusha
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stc
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int 13h
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jnc read_fat_ok
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call reset_floppy
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jnc read_fat
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fatal_disk_error:
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mov si, disk_error
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call print_string
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jmp reboot
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read_fat_ok:
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popa
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mov ax, 2000h
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mov es, ax
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mov bx, 0
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mov ah, 2
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mov al, 1
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push ax
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load_file_sector:
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mov ax, word [cluster]
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add ax, 31
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call l2hts
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mov ax, 2000h
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mov es, ax
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mov bx, word [pointer]
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pop ax
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push ax
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stc
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int 13h
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jnc calculate_next_cluster
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call reset_floppy
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jmp load_file_sector
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calculate_next_cluster:
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mov ax, [cluster]
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mov dx, 0
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mov bx, 3
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mul bx
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mov bx, 2
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div bx
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mov si, buffer
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add si, ax
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mov ax, word [ds:si]
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or dx, dx
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jz even
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odd:
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shr ax, 4
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jmp short next_cluster_cont
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even:
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and ax, 0FFFh
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next_cluster_cont:
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mov word [cluster], ax
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cmp ax, 0FF8h
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jae end
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add word [pointer], 512
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jmp load_file_sector
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end:
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pop ax
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mov dl, byte [bootdev]
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jmp 2000h:0000h
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reboot:
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mov ax, 0
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int 16h
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mov ax, 0
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int 19h
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print_string:
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pusha
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mov ah, 0Eh
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.repeat:
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lodsb
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cmp al, 0
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je .done
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int 10h
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jmp short .repeat
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.done:
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popa
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ret
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reset_floppy:
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push ax
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push dx
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mov ax, 0
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mov dl, byte [bootdev]
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stc
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int 13h
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pop dx
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pop ax
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ret
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l2hts:
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push bx
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push ax
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mov bx, ax
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mov dx, 0
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div word [SectorsPerTrack]
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add dl, 01h
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mov cl, dl
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mov ax, bx
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mov dx, 0
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div word [SectorsPerTrack]
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mov dx, 0
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div word [Sides]
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mov dh, dl
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mov ch, al
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pop ax
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pop bx
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mov dl, byte [bootdev]
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ret
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kern_filename db "KERNEL BIN"
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disk_error db "Floppy error! Press any key...", 0
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file_not_found db "KERNEL.BIN not found!", 0
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bootdev db 0
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cluster dw 0
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pointer dw 0
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times 510-($-$$) db 0
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dw 0AA55h
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buffer:
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321+

‎bootloader.bin

512 Bytes
Binary file not shown.

‎kernel.asm

Lines changed: 65 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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1+
BITS 16
2+
[org 0]
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mov ax,cs
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mov ds,ax
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mov es,ax
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mov ax,0x7000
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mov ss,ax
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mov sp,ss
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start:
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mov al,03h
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mov ah,0
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int 10h
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_mouser:
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mov ah,02h
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mov dl,bl
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int 10h
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mov ah , 80h
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int 16h
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cmp al,08h
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je _backspace
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cmp al,09h
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jge _print
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cmp al,07h
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jae _print
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jmp _mouser
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_backspace:
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sub bl,1h
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jmp _backspace2
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_backspace2:
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mov ah,0eh
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mov al,20h
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int 10h
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jmp _mouser
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_down:
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add cl,1h
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jmp _mouser
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_up:
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sub cl,1h
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jmp _mouser
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_left:
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sub bl,1h
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jmp _mouser
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_right:
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add bl,1h
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jmp _mouser
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_print:
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mov ah,0eh
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cmp al,80h
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je _down
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int 10h
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jmp _right
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ret

‎kernel.bin

95 Bytes
Binary file not shown.

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