CompuPro - System Support 2 Board
The System Support 2 board was essentially an improvement on the CompuPro System Support 1 board.

This board provided the system with sophisticated control of bus interrupts, independent interval timers, a "real time" clock/calendar that provides BCD hours/minutes/seconds /month/day/year with battery backup, and full RS-232 serial channels which included full handshaking.
 
The manual for this board can be obtained here.
    
Other CompuPro S-100 Boards
CPU8085-88  CPU86-87  CPU-Z  Disk1  Disk1A  Disk1B  Disk2  Disk3   EconoROM2708  Interfacer 1  
RAM Boards   Interfacer 3  Interfacer 4  Interfacer II   M-Drive  MPX-Board  PC-Video  
System-Support1  System-Support2   SPIO  Spectrum  SP186   CPU-286   68000  32016  SPUZ