BIOS / Int / Int 15 / 89


          INT 15 - SYSTEM - SWITCH TO VIRTUAL MODE (AT,XT286,PS50+)

Input			Output
AX	89h		FFh = Line20 Err	AX
BX	IRQ0 Interrupt	IRQ8 Interrupt		BX
CX	Offset into PM CS to jump to			CX
DX				DX
DS:SI	GDT for Protected Mode		Set on Error	CF

        IRQ1 - 7 use the next 7 interrupts after IRQ0
        IRQ9 - F use the next 7 interrupts after IRQ8

GDT for Protected Mode

        offset 0h  null descriptor
               8h  GDT descriptor
              10h  IDT descriptor
              18h  DS
              20h  ES
              28h  SS
              30h  CS
              38h  uninitialized, used to build descriptor for BIOS CS