Around the year 2000, A Fox Consulting & Design became involved with the Intel MCS-51 family of microcontrollers, specifically the 8051/52 and 8031/32. In an effort to understand the architecture of the MCS-51 line and experiment with interfacing to it we began developing a single-board computer solution for the microcontroller.
The end result of these studies was a small line of prototype circuit boards dubbed the "Fox-Com System", the first board being the base or "motherboard" which held the CPU and main memory. From there we could add on various custom modules:
Completed and assembled
Fox-Com CPU/Memory board)
The motherboard holds the CPU, main memory, and serial port for PC communications. Jumper selectors allow configuring the memory for read-only and using a null modem vs. standard serial cable with the serial port.
The board includes 8K of monitor ROM to allow reading and writing of memory, displaying status, executing programs, and interfacing with a PC to download programs to RAM. The monitor ROM also provides a jump table of various utility and data conversion routines.
The board was designed with headers and mounting holes for stand-off spacers so that additional daughterboards could be stacked on top of the main motherboard.
The board is intended to be powered from a +9DVC power source.
The first daughterboard that was developed was a basic display/keypad interface to facilitate basic programming and testing of the Fox-Com system.
The second daughterboard that was developed has yet to leave the rough prototyping phase (as can be seen from the various ECOs). This is a mish-mash of various technologies we wanted to try out with the MCS-51 system.
The Fox-Com system is still only a functional prototype, but should further interest in the MCS-51 line warrent it, the system can be revitalized.