PORTIBM PC Portable (uses same BIOS as XT) 0210-0217 - Expansion unit (XTIBM PC XT)

0210  -W  latch expansion bus data
0210  R-  verify expansion bus data
0211  -W  clear wait, test latch
0211  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)
0214  R-  read data   (receiver card port)
0215  R-  High byte of address, then Low byte	(receiver card port)