0090-009F ---- PS/2 POS (Programmable Option Select)


0090       Central arbitration control port
0091       Card selection feedback

0092   r/w PS/2 system control port A  (port B is at 0061)
        bit 7-6   any bit set to 1 turns activity light on
        bit 5     reserved
        bit 4 = 1 watchdog timout occurred
        bit 3 = 0 RTC/CMOS security lock (on password area) unlocked
              = 1 CMOS locked (done by POST)
        bit 2     reserved
        bit 1 = 1 indicates A20 active
        bit 0 = 0 system reset or write
            1 pulse alternate reset pin (alternate CPU reset)

0094   w   system board enable/setup register
        bit 7 = 1  enable functions
              = 0  setup functions
        bit 5 = 1  enables VGA
              = 0  setup VGA

0095       reserved

0096   w   adapter enable /setup register
        bit 3 = 1  setup adapters
              = 0  enable registers

0097       reserved