sw4     sw3     sw2     sw1     Monitor
on      on      on      on      IBM VGA color/mono
on      on      on      off     non IBM VGA mono
on      on      off     on      non IBM VGA color
on      on      off     off     non IBM VGA 16"
on      off     on      on      MDA_NMI_OFF
on      off     on      off     EGA NMI_OFF
on      off     off     on      NEC_4D/NEC_5D
on      off     off     off     reserved
off     on      on      on      MDA
off     on      on      off     CGA
off     on      off     on      EGA
off     on      off     off     NEC
off     off     on      on      NEC+
off     off     on      off     NEC 2A
off     off     off     on      NEC XL