$D0BC/53433/SCPU+76:   DOS Extension-/RAMLink Hardware Reg. Flag

   +-------+--------------------------------------------------------+
   | Bit 7 |   DOS Extension Mode Flag: 1 = Enabled                 |
   | Bit 6 |   RAMLink Hardware Registers Flag: 1 = Enabled         |
   +-------+--------------------------------------------------------+

     This register is read only with hardware registers disabled,
     Read/Write with hardware registers enabled.