Config Mapping Register

Number	TBRegisterNumber::$04
Readable	TBRegisterReadable::No
Writable	TBRegisterWritable::Yes
Short Description	ShortDesc::In config mode, allows RAM to be mapped to ROM area.

Write (config mode only, bootrom disabled):

  bits 7:5 = Reserved, must be 0
  bits 4:0 = 16K SRAM bank mapped to 0x0000-0x3FFF (first 1MB of SRAM) (hard reset = 0)