Cromemco TU-ART Board  
This was the main I/O board Cromemco utilized for their systems to communicate with the printer or CRT terminal(s).

The TU-ART (Twin Universal Asynchronous Receiver and Transmitter) provided two channels of duplex serial data exchange; two channels of parallel data exchange; and ten interval timers. Status information was available through polling or via interrupt. In addition, each interval timer activated an interrupt and two interrupt request lines were brought out for the user. The TU-ART has its own crystal-controlled clock and interfaces to the S-100 bus asynchronously so that CPU clock frequency was not critical. The board incorporated two TMS 5501 NMOS I/O Controller chips. The only problem with the board was that it ate up a big chunk of the 256 byte system I/O address space.  Below is table of the essential requirements.