1 files changed, 8 insertions, 0 deletions
diff --git a/boot/mbr.asm b/boot/mbr.asm
index bb74d23..4a75e3e 100644
--- a/boot/mbr.asm
+++ b/boot/mbr.asm
@@ -141,6 +141,14 @@ boot_16:
 boot_32_pm:
 ;
 
+;    ;enable A20
+;    ;http://www.brokenthorn.com/Resources/OSDev9.html
+;    ;Method 3.1: Enables A20 through keyboard controller
+;    ;Not all keyboard controllers support this
+;    ;todo: check if this has any effect at all !?!?
+     mov al, 0xdd  ; command 0xdd: enable a20
+;   ;mov al, 0xdf  ; command 0xdf: disable a20
+     out 0x64, al  ; send command to controller
 ;
     call KERNEL_OFFSET			        ;jump into our Kernel!
 ;