second commit

sectcl.nasm

@@ -1,25 +1,33 @@
 ; x86-16 BIOS bootloader
 [BITS 16]
 [ORG 0x7C00]
-; jmp 0x7C00:start
-start:
+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 start
+jmp main
 
 ; REGISTERS
-;       SP: 'top of memory'
 ;	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
+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
@@ -27,6 +35,8 @@ call    PutChar
 .ret:   ret
 
 
+
+
 ; fill up sector, add boot signature
 TIMES 510 - ($ - $$) db 0
 DW 0xAA55