MS-9802 Mainboard
6-14
90  Initialization of system management interrupts by invoking all handlers. Please note this 
checkpoint comes right after checkpoint 20h 
A1  Clean-up work needed before booting to OS. 
A2  Takes care of runtime image preparation for different BIOS modules. Fill the free area in 
F000h segment with 0FFh. Initializes the Microsoft IRQ Routing Table. Prepares the 
runtime language module. Disables the system configuration display if needed. 
A4  Initialize runtime language module. Display boot option popup menu. 
A7  Displays the system configuration screen if enabled. Initialize the CPU’s before boot, 
which includes the programming of the MTRR’s. 
A9  Wait for user input at config display if needed. 
AA  Uninstall POST INT1Ch vector and INT09h vector. 
AB  Prepare BBS for Int 19 boot. Init MP tables. 
AC  End of POST initialization of chipset registers. De-initializes the ADM module. 
B1  Save system context for ACPI. Prepare CPU for OS boot including final MTRR values. 
00  Passes control to OS Loader (typically INT19h).