early beginnings of a bootloader.. codenamed PINE

pine.asm

; -- nasm -f bin pine.s -o pine.bin
; -- copy pine.bin pine.img
; -- boot!

[BITS 16]               ; make this into 16bit code
[ORG 0x7C00]            ; load into memory here

_main:
mov ax, 0x0000          ; setup the data segment register (step1)
mov ds, ax              ; move ax into ds (step2)
mov si, _testString     ; a tmp test string to display
call _pChar             ; run the put char proc
jmp $                   ; jmp to the start of the instruction

_pChar:
mov ah, 0x0E            ; put char on screen function
mov bh, 0x00            ; page number
mov bl, 0x07            ; txt attrib (bg and fg) [white - black]

._nxtChar:              ; label (for loopinf around for the next char)
lodsb                   ; load the contents of SI int AL and [inc SI]
or al, al               ; sets the Zero Flag if AL is null
jz ._return             ; if ZF = null go to the end of the proc
int 0x10                ; call the bios video interrupt
jmp ._nxtChar           ; loop around back to the top
._return:
ret                     ; leave and proceed (CALL)

_testHugeNum dd 0x00    ; 1 dw   -> FFFFFFFF
_testLargNum dw 0x00    ; 1 word -> FFFF
_testSmalNum db 0x00    ; 1 byte -> FF
_testString db \
'A simple test from the pine bootloader.', 0x0D, 0x0A, '[halt]', 0

times 510-($-$$) db 0   ; fill the rest of the sector with 0s
dw 0xAA55               ; add the bootloader sig at the end