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58 lines
1.2 KiB
58 lines
1.2 KiB
BITS 16 |
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start: |
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mov ax, 07C0h ; Set up 4K stack space after this bootloader |
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add ax, 288 ; (4096 + 512) / 16 bytes per paragraph |
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mov ss, ax |
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mov sp, 4096 |
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mov ax, 07C0h ; Set data segment to where we're loaded |
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add ax, 255 |
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mov ds, ax |
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main_loop: |
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call read_char ; Read character |
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jmp main_loop ; Repeat |
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read_char: |
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mov ah, 0h ; Call Function "Read Char" |
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int 16h ; Execute Keyboard Services |
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mov ah, 0eh ; Call Function "Write char to TTY |
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int 10h ; Execute Video Services |
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cmp AL, 0x0d ; Insert new line, if keystroke was return |
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je new_line |
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ret |
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new_line: |
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mov AH, 03h ; Get Cursor position |
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int 10h |
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add DH, 1 ; Add 1 to cursor position |
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mov AH, 02h ; Set Cursor to new position |
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int 10h |
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ret |
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print_string: ; Routine: output string in SI to screen |
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mov ah, 0Eh ; int 10h 'print char' function |
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.repeat: |
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lodsb ; Get character from string |
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cmp al, 0 |
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je .done ; If char is zero, end of string |
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int 10h ; Otherwise, print it |
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jmp .repeat |
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.done: |
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ret |
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times 510-($-$$) db 0 ; Pad remainder of boot sector with 0s |
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dw 0xAA55 ; The standard PC boot signature |
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