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