M3SE feature control and identification registers

M3SE contains a pair of registers whose bits control various features. The "disable" bits are included to enable the use of other peripherals that might conflict with M3SE I/O port addresses.

	Port 0xBE (R/W):
		 Bit  6  - Disable VGA registers (display stays active)
 		 Bit  5  - Disable network module access
 		 Bit  4  - Disable M3SE ID/version registers
 		 Bit  3  - Disable IDE/CF access
 		 Bit  2  - Disable joystick port
 		 Bit  1  - Joystick 4-bit mode
 		 
 	Port 0xBF (R/W):
 		 Bit  5  - DIP switch 2 in ON position
 		 Bit  4  - DIP switch 1 in ON position
 		 Bit  3  - 4MHz fast CPU mode detected (read only)
		 Bit  1  - Allow RTCC seconds to be set nonzero
		 Bit  0  - RTCC register write protect

M3SE contains four read-only registers to allow product and revision identification:

	Port 0x40 (R/O):
	    Bits 7:0 - Product identifier (M3SE = 0x02)
	
	Port 0x41: (R/O):
	    Bits 7:4 - PCB major revision number
	    Bits 3:0 - PCB minor revision number
	    
	Ports 0x42-0x43 (R/O):
	    Bits 15:9 - Firmware year - 2000
	    Bits  8:5 - Firmware month 1-12
	    Bits  4:0 - Firmware day of month 1-31

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