Fix trampling of last digit in dumpax_os

lib/os_lib.nasm

@@ -35,20 +35,20 @@ printALChar:
 
 dumpax_os:
     pusha           ; save registers
-    mov bx, ax
+    mov dx, ax
     mov ah, 0xE     ; Teletype output
 
     mov cx, 4       ; 4 nipples in a 16 bit word
     .loop:
-    rol bx, 4       ; rotate to next nipple
-    mov al, bl      ; we copy to al because we need to mask only the low 4 bits
+    rol dx, 4       ; rotate to next nipple
+    mov al, dl      ; we copy to al because we need to mask only the low 4 bits
     and al, 1111b   ; Do the masking
     add al, '0'     ; convert to ASCII
     cmp al, '9'     ; If we are greater than 9 ascii, we add 7 to make digit 10 be represented as 'A'
     jbe .skip       ;  -|-
     add al, 7       ;  -|-
     .skip:          ;  -|-
-    mov bl, 0x02 ;color
+    mov bl, 0xe2 ;color
     int 0x10        ; BIOS call 'output'
     loop .loop
 
@@ -63,4 +63,4 @@ os_change_screen:
         ; and base pointer has to be set. 
         mov ah, 0x05
         int 0x10
-        ret
+        ret