INT 2F U - DOS 5.0 DOSSHELL - TASK SWITCHING API???
        AX = 4A05h
        SI = function
            0000h reset???
            0001h ???
            0002h ???
            0003h ???
            0004h ???
                BL = ???
            0005h ???
            0006h get ???
                Return: ES:DI -> ???
            0007h get ???
                Return: AX = ???
            0008h get ???
                Return: DX:AX -> ???
            0009h get ???
                Return: ES = ???
            000Ah ???
                BL = ???
                ES:DI -> ???
            000Bh get ???
                Return: AX = ???
            000Ch ???
                BL = ???
                Return: DX:AX -> ???
Notes:  DOSSHELL chains to the previous handler if SI is not one of the values
          listed above
        the DOSSWAP.EXE module calls functions 03h,04h,05h,07h,08h,09h,0Ch
        the Windows 3.1 DSWAP.EXE and WSWAP.EXE task switchers use these calls