)
Values for special flag PSP segments:
 0000h	free
 0006h	DR DOS XMS UMB
 0007h	DR DOS excluded upper memory ("hole")
 0008h	belongs to DOS
 FFF7h	386MAX v6.01+ ???
 FFFAh	386MAX UMB control block (see #01477 at AX=4402h"386MAX")
 FFFDh	386MAX locked-out memory
 FFFEh	386MAX UMB (normally immediately follows its control block)
 FFFFh	386MAX v6.01+ device driver