The PC-Co (PC) is a low-cost I/O board with up to 100 I/O lines and a PC-ISA bus. You may use the PC-Co as a standalone controller or install it in a PC ISA slot as a co-processor board. It contains three power relays (5 A). It also has four solenoid drivers capable of sinking 350 mA at 50V. Three PPIs (82C55) provide 72 I/O lines, and a special interface supports LCD modules. An on-board -12V power supply on-board makes it possible to support graphical modules as well. The PC-CO can support as many as four serial ports, with three of the ports coming from the installed processor controller, and the fourth on an optional SCC2691. The SCC2691 port can be configured as RS232 or RS485, while the other three are RS232. A DB25 connector provides three power relay contacts (NC, NO, COM), four solenoid drivers, and nine TTL I/O lines from the installed processor controller.