assembly/bootloader.asm at main · lesacar/assembly · GitHub

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bits 16

mov ax, 0x07C0
mov ds, ax
mov ax, 0x07E0
mov ss, ax
mov sp, 0x2000

call clearscreen

push 0x0000
call movecursor
add sp, 2

push msg
call print
add sp, 2

cli
hlt

clearscreen:
    push bp
    mov bp, sp
    pusha

    mov ah, 0x07
    mov al, 0x00
    mov bh, 0x07
    mov cx, 0x00
    mov dh, 0x18
    mov dl, 0x4f
    int 0x10

    popa
    mov sp, bp
    pop bp
    ret

movecursor:
    push bp
    mov bp, sp
    pusha

    mov dx, [bp+4]
    mov ah, 0x02
    mov bh, 0x00
    int 0x10

    popa
    mov sp, bp
    pop bp
    ret

print:
    push bp
    mov bp, sp
    pusha
    mov si, [bp+4]
    mov bh, 0x00
    mov bl, 0x00
    mov ah, 0x0E
.char:
    mov al, [si]
    add si, 1
    or al, 0
    je .return
    int 0x10
    jmp .char
.return:
    popa
    mov sp, bp
    pop bp
    ret


msg:    db "Test string", 0

times 510-($-$$) db 0
dw 0xAA55