High Quality Content by WIKIPEDIA articles! The Big Board (1980) and Big Board II (1982) were Z80 based single-board computers designed by Jim Ferguson. They provided a complete CP/M compatible computer system on a single printed circuit board, including CPU, memory, disk drive interface, keyboard and video monitor interface. The printed circuit board was sized so as to allow attachment to an 8 inch floppy disk drive. The Big Board II added a hard disk drive interface, enhancements to system speed (4MHz vs. 2.5MHz) and enhancements to the terminal interface. One version of the Big Board was used in the Xerox 820.