; x86-16 BIOS bootloader
[BITS 16]
[ORG 0x7C00]
MOV AX, 0x7E00>>4       ; segment address
MOV SS, AX              ; set stack segment
MOV SP, 0xFFFF          ; put stack at top of segment
MOV DS, AX              ; set data segment
XOR BP, BP
jmp 0x0:main    ; can probably be removed to save 5 bytes?

main:
call GetChar
jmp main

; REGISTERS
;	BP: points to variable map
;       stack: managed
;	others: general purpose

; GetChar :: () -> (AL)
GetChar:
xor     AX,AX			; clear AH
int     0x16			; read key via BIOS
; read key is now in AL
; fallthrough to PutChar to echo read key

; PutChar :: (AL) -> (AL)
PutChar:
mov     AH,0xe		; TTY mode
int     0x10		; print character in AL
cmp     AL, 13          ; if \r, print \r\n and return \n
jne     .ret
mov     AL, 10
call    PutChar
.ret:   ret




; fill up sector, add boot signature
TIMES 510 - ($ - $$) db 0
DW 0xAA55