Bitfields for RM386 global flags 1:
Bit(s)	Description	)
 0-3	reserved
 4	V86 mode
 5	reserved
 6	80386 or higher CPU
 7,8	reserved
 9	A20 enabled at startup
 10	"HIGH_IO"
 11	ROM
 12	large frame
 13,14	reserved
 15	PS/2-style A20 control