Recent from talks
Ferguson Big Board
Knowledge base stats:
Talk channels stats:
Members stats:
Ferguson Big Board
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 to match the Shugart 801 or 851 floppy drive. This allowed attachment to up to two 8 or 5.25-inch floppy disk drives. The Big Board II added a SASI interface for hard disk drives, enhancements to system speed (4 MHz vs. 2.5 MHz) and enhancements to the terminal interface.
One version of the Big Board was used in the Xerox 820.
The Big Board was sold as an unpopulated printed circuit board with sockets for integrated circuits, with documentation and options to purchase additional components . The Big Board design was simple enough to build a system around that many people with no prior electronics experience were able to build and bring up a capable computer system of their own at a cost far less than that of a fully assembled system of the time. In this way, the Big Boards anticipated the DIY PC clones that became popular later. In its most popular form, the fully assembled and tested Big Board need only be connected to a power supply, one or two eight-inch floppy disk drives, a composite monitor, and an ASCII encoded keyboard in order to provide a fully functioning system. A serial terminal could be used in place of the monitor and keyboard, further simplifying assembly. The only tool required for basic assembly was a screwdriver for the terminal block power connections.
The design was also simple to modify for the sake of system expansion and enhancement. Many different modifications to increase the system clock speed were possible, including some that required nothing more than jumpers (e.g. the 3.5 MHz speed upgrade obtained by jumpering the clock divider, with no software modifications or changes to the ICs on the board.) There was also a minor industry in user-installable system upgrades such as real time clocks, 4 MHz upgrades, double density floppy upgrades, character enhancements for the display (reverse video, blinking, etc.), and the addition of hard disk interfaces such as SASI and SCSI. Most of these upgrades were accomplished through the use of daughter boards that plugged into existing IC sockets on the board, with the original IC either replaced by a more capable IC or placed into a socket on the daughter board.
It was possible to upgrade the memory to 256 KB, which was extremely large for the time. While not directly supported by CP/M, the extra memory could be used to implement a ram disk, caching of the operating system image (to greatly improve warm boot time), or a print spooler.
The Big Board II (1982) incorporated many of the most popular upgrades for the original Big Board into its design. It also featured a small breadboard area that allowed for many simple upgrades to be performed without the addition of daughter boards.
The Big Board was designed primarily to run the CP/M operating system, version 2.2. 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. PFM featured many well-documented routines that could be employed in user code.
The board featured 3 spare 2K ROM sockets that allowed for the addition of additional firmware. Popular additions were Tiny BASIC, FORTH, and enhanced versions of PFM.
Hub AI
Ferguson Big Board AI simulator
(@Ferguson Big Board_simulator)
Ferguson Big Board
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 to match the Shugart 801 or 851 floppy drive. This allowed attachment to up to two 8 or 5.25-inch floppy disk drives. The Big Board II added a SASI interface for hard disk drives, enhancements to system speed (4 MHz vs. 2.5 MHz) and enhancements to the terminal interface.
One version of the Big Board was used in the Xerox 820.
The Big Board was sold as an unpopulated printed circuit board with sockets for integrated circuits, with documentation and options to purchase additional components . The Big Board design was simple enough to build a system around that many people with no prior electronics experience were able to build and bring up a capable computer system of their own at a cost far less than that of a fully assembled system of the time. In this way, the Big Boards anticipated the DIY PC clones that became popular later. In its most popular form, the fully assembled and tested Big Board need only be connected to a power supply, one or two eight-inch floppy disk drives, a composite monitor, and an ASCII encoded keyboard in order to provide a fully functioning system. A serial terminal could be used in place of the monitor and keyboard, further simplifying assembly. The only tool required for basic assembly was a screwdriver for the terminal block power connections.
The design was also simple to modify for the sake of system expansion and enhancement. Many different modifications to increase the system clock speed were possible, including some that required nothing more than jumpers (e.g. the 3.5 MHz speed upgrade obtained by jumpering the clock divider, with no software modifications or changes to the ICs on the board.) There was also a minor industry in user-installable system upgrades such as real time clocks, 4 MHz upgrades, double density floppy upgrades, character enhancements for the display (reverse video, blinking, etc.), and the addition of hard disk interfaces such as SASI and SCSI. Most of these upgrades were accomplished through the use of daughter boards that plugged into existing IC sockets on the board, with the original IC either replaced by a more capable IC or placed into a socket on the daughter board.
It was possible to upgrade the memory to 256 KB, which was extremely large for the time. While not directly supported by CP/M, the extra memory could be used to implement a ram disk, caching of the operating system image (to greatly improve warm boot time), or a print spooler.
The Big Board II (1982) incorporated many of the most popular upgrades for the original Big Board into its design. It also featured a small breadboard area that allowed for many simple upgrades to be performed without the addition of daughter boards.
The Big Board was designed primarily to run the CP/M operating system, version 2.2. 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. PFM featured many well-documented routines that could be employed in user code.
The board featured 3 spare 2K ROM sockets that allowed for the addition of additional firmware. Popular additions were Tiny BASIC, FORTH, and enhanced versions of PFM.
Recent media