The Big Board and Big Board II are single board computers designed by Jim Ferguson. Both provide a complete [wiki]CP/M[/wiki] compatible computer systems on a single printed circuit board. The Big Board I, also known as "The Ferguson", was released in 1980. The Big Board II provided several enhancements over the original Big Board, and was released in 1982.
[wiki="Image:BigBoardI-Full.png"]thumb|right|alt=Fully Assembled Big Board I|Assembled Big Board I[/wiki]
[wiki="Image:BBI.jpg"]thumb|right|alt=Big Board I System Enclosure|Big Board I System in Enclosure[/wiki]
[wiki="Image:BBI-inside.jpg"]thumb|right|alt=Big Board I in terminal-style enclosure with ASCII keyboard and display|Big Board I in Terminal-Style Enclosure, opened to show PCB[/wiki]
The Big Board was sold through Digital Research Computers (of Texas) in configurations ranging from a bare printed circuit card with assembly instructions to a fully assembled and tested PCB with CP/M and manuals. The purchaser provided their own enclosure, keyboard, display, and disk drives to obtain a complete system.
The Big Board II was sold in a similar fashion, through a larger number of outlets.
Specifications

Big Board I
  • [wiki="Zilog Z80"]Z80[/wiki] at 2.5MHz.
  • 64 KB dynamic in 32 4116's or equivalent.
  • An [wiki]ASCII[/wiki] [wiki="Computer keyboard"]keyboard[/wiki] interface.
  • A [wiki="Transistor?transistor logic"]TTL[/wiki] / [wiki]composite video[/wiki] [wiki="cathode ray tube"]CRT[/wiki] interface allowing a display of 24 lines by 80 characters.
  • A SS/SD floppy disk interface allowing addition of up to four 8" [wiki]Shugart Associates[/wiki] SA800 compatible 8" [wiki]floppy disk[/wiki] drives.
  • Two (optional) [wiki]RS-232[/wiki] serial ports.
  • A parallel [wiki]Centronics[/wiki] compatible printer port.
  • Optional real time clock.
  • 3 Spare ROM/EPROM sockets for 2K memory devices.

Big Board II
  • [wiki="Zilog Z80"]Z80[/wiki] [wiki]CPU[/wiki] at 4MHz.
  • 64 KB dynamic [wiki]RAM[/wiki] in 8 4164's or equivalent.
  • [wiki]SASI[/wiki]/[wiki]SCSI[/wiki] hard disk interface, also usable as a general purpose I/O or for control of other SCSI devices.
  • An [wiki]ASCII[/wiki] [wiki="Computer keyboard"]keyboard[/wiki] interface.
  • A [wiki="Transistor?transistor logic"]TTL[/wiki] / [wiki]composite video[/wiki] [wiki="cathode ray tube"]CRT[/wiki] interface allowing a display of 24 lines by 80 characters.
  • A DS/DD floppy disk interface allowing addition of up to four 8" or 5.25" [wiki]floppy disk[/wiki] drives.
  • Two [wiki]RS-232[/wiki] serial ports via a Z80 SIO.
  • A parallel [wiki]Centronics[/wiki] compatible printer port via a Z80 PIO.
  • Optional real time clock.
  • 6 ROM/EPROM sockets, including ability to program EPROMs in place.
  • Breadboard area to allow upgrades without the use of daughterboards.

The form factor of the PCB for both systems was chosen to allow them to be piggybacked on an 8" floppy disk drive.
Documentation

The Big Board came with a full set of [wiki="schematic"]schematics[/wiki], a document titled '"Theory of Operation", the PFM-80 User's Manual', instructions for assembly and testing of the Big Board, a parts list, and addenda to these. The Theory of Operation described the details of the operation of the system, including the [wiki="Video_Display_Controller"]CRT controller[/wiki], [wiki]floppy disk controller[/wiki], [wiki="serial_communication"]serial communications[/wiki], memory [wiki]bank switching[/wiki], and connector [wiki="pinout"]pinouts[/wiki].
Software

The Big Board was designed primarily to run the [wiki]CP/M[/wiki] [wiki]operating system[/wiki], version 2.2.(J.B. Ferguson: 'The Bigboard: An Overview', 1980.) It came with a monitor program in ROM called PFM-80 which was the "software front panel" of the system. The source code listing of PFM was a feature of the first and second issues of Micro Cornucopia (Don Retzlaff: "PFM-80 Monitor", 'Micro Cornucopia', No. 1, pg. 9, July, 1981.) PFM features many well-documented routines that can be employed in user code.(Russel Smith: PFM-80 Users Manual, 1980.)
The boards feature extra [wiki="Read-only memory"]ROM[/wiki] sockets for optional [wiki]firmware[/wiki]. Popular additions are [wiki]Tiny BASIC[/wiki], [wiki]FORTH[/wiki](Rob DeVoe: '"A Self-Loading ROM"', 'Micro Cornucopia', No. 6, pg. 10, June, 1982.), and enhanced versions of PFM. The BBII is capable of programming EPROMs on-board.
Big Board Community

The success of the Big Board spawned [wiki]Micro Cornucopia[/wiki] magazine (David Thompson: '"Spare a Dime?"', 'Micro Cornucopia' No.6, pg. 2, June, 1982) Many Big Board kits included a subscription flyer for the magazine.
'MicroC', as it was known to readers, featured user reports, hardware upgrade articles, and reviews of third party products. The magazine's publisher hosted the SOG (Semi Official Get-together) annually, where the magazine's readers would join staff and writers for white water rafting, potluck feasts, and technical discussions.[footnote]J.D. Thompson: "All Wet!", 'Micro Cornucopia', No. 12, Pg 2, June 1983.[/footnote] Over time the magazine's coverage expanded to systems related to or based on the Big Board, including the Xerox 820 series (licensed designed based on the Big Board) and the Kaypro CP/M computers.
External links


[wiki]Category:Systems[/wiki]