The board was claimed to be S-100 compatible. (This needs to be confirmed since their AM-100 CPU was not).  It had four RS-232 I/O ports which were independently controlled by an onboard Z80 and DMA controller.  Again this board was clearly designed for an efficient multiuser serial I/O system.  

The manual for this board can be obtained here.
 

Other Alpha Micro  S-100 Boards
AM-100 CPU Board      AM-300 Serial I/O     AM-310 Serial I/O   AM-500  HDC   AM-600T  AM-200 FDC  Other Boards