mirror of
https://github.com/gbowne1/ClassicOS.git
synced 2024-11-22 22:26:51 -08:00
62 lines
1.1 KiB
NASM
62 lines
1.1 KiB
NASM
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; Set up the segment registers
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xor ax, ax
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mov ds, ax
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mov es, ax
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; Set up stack and jump to main
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mov ss, ax
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mov sp, 0x7c00
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jmp main
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; Print 'Booting ClassicOS!' to the screen
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print:
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mov si, message
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mov ah, 0x0e
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.loop:
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lodsb
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test al, al
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jz .done
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int 0x10
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jmp .loop
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.done:
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ret
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; Set the video mode to a 40 column text mode
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set_video_mode:
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mov ax, 0x0003 ; Set up a 80x25 text mode
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int 0x10
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; Set the number of columns to 40
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mov ax, 0x1112
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mov bx, 0x0007
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int 0x10
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ret
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; Bootloader entry point
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main:
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; Call the set_video_mode function
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call set_video_mode
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; Clear the screen
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mov ah, 0x06
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mov al, 0
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xor bx, bx
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xor cx, cx
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mov dh, 24
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mov dl, 39
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int 0x10
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; Call the print function
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call print
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; Infinite loop
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.loop:
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jmp .loop
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; Message to print
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message db 'Booting ClassicOS!', 0
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times 510-($-$$) db 0
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dw 0xaa55
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