0210-0217 ---- Expansion unit (XT)


0210   w   latch expansion bus data
   r   verify expansion bus data
0211   w   clear wait, test latch
   r   High byte data address
0212   r   Low byte data address
0213   w   0=enable,  1=disable expansion unit
0214   w   latch data  (receiver card port)
   r   read data   (receiver card port)
0215   r   High byte of address, then Low byte   (receiver card port)