Enable A20 by using int 0x15 (ax=0x2401)
Posted: Fri Jan 11, 2002 12:00 am
Hi.
I want to enable the A20 address line using this ([1]) BIOS function.
The problem is, that I don't know whether what "secure mode" of a
keyboard controller is, nor how to disable it.
I've been searching the internet for implementations or better
documentations of this function but I couldn't find any.
Can you please explain me, what this "secure mode" means and how to
disable it.
Thanks
Jan
[1] (an extract of Ralph Brown's Interrupt List)
(http://www-2.cs.cmu.edu/afs/cs/user/ral ... files.html)
INT 15 - SYSTEM - later PS/2s - ENABLE A20 GATE
AX = 2401h
Return: CF clear if successful
AH = 0x00
CF set on error
AH = 0x01: keyboard controller is in secure mode
AH = 0x86: function not supported
I want to enable the A20 address line using this ([1]) BIOS function.
The problem is, that I don't know whether what "secure mode" of a
keyboard controller is, nor how to disable it.
I've been searching the internet for implementations or better
documentations of this function but I couldn't find any.
Can you please explain me, what this "secure mode" means and how to
disable it.
Thanks
Jan
[1] (an extract of Ralph Brown's Interrupt List)
(http://www-2.cs.cmu.edu/afs/cs/user/ral ... files.html)
INT 15 - SYSTEM - later PS/2s - ENABLE A20 GATE
AX = 2401h
Return: CF clear if successful
AH = 0x00
CF set on error
AH = 0x01: keyboard controller is in secure mode
AH = 0x86: function not supported