Implement color changing

This reverts commit d63c2cbd69.

messages.asm

@@ -21,9 +21,6 @@ mov dh, HEIGHT
 mov dl, WIDTH
 int 0x10
 
-;; Turn on interrupts
-sti
-
 ;; Set cursor to bottom of screen
 mov dh, HEIGHT
 mov dl, 0x00
@@ -31,33 +28,10 @@ mov bh, 0x00
 mov ah, 0x02
 int 0x10
 
-;; Start serial connection
-mov ah, 0
-mov al, 0b11100011
-mov dx, 0
-int 0x14
-
 .loop:
-        ;; Print a '.' to debug
+        ;; Read character
-        mov ah, 0x01
+        mov ah, 0x00
-        mov al, '.'
+        int 0x16
-        mov dx, 0
-        int 0x14
-
-
-        ;; Check status of COM1
-        mov ah, 0x03
-        mov dx, 0
-        int 0x14
-
-        ;; If not ok, wait
-        and ah, 0x01
-        jz .loop
-
-        ;; If ok, start reading character
-        mov ah, 0x02
-        mov dx, 0
-        int 0x14
 
         cmp al, 0x0d ; newline
         je .newline
@@ -69,6 +43,18 @@ int 0x14
         ;; Read character
         mov ah, 0x00
         int 0x16
+        ;; Read character is in al
+        sub al, 'a'
+        mov bl, al
+        shl bl, 0x4
+
+        ;; Read character
+        mov ah, 0x00
+        int 0x16
+        ;; Read character is in al
+        sub al, 'a'
+        or al, bl
+
         mov [color_mode], al
         jmp .loop
 
@@ -98,11 +84,11 @@ int 0x14
 .nonewline:
 
         ;; Write character
-        mov ah, 0x09
+	    mov ah, 0x09
         mov bh, 0x00
         mov bl, [color_mode]
         mov cx, 0x01
-        int 0x10
+	    int 0x10
 
         ;; Get current cursor position
         mov ah, 0x03
@@ -142,7 +128,7 @@ int 0x14
 
 halt:	hlt
 
-color_mode: db 0x05
+color_mode: db 0x02
 
 times 510 - ($ - $$) db 0
 dw 0xAA55