I was the Principal Technical Consultant on the Xerox 2700/3700 and 4235 (follow
on product). It is the ESS (Electronic Sub System) of a Xerox 3700 LPS (Laser
Printing System) printing at 24 ppm. The ESS receives print jobs from a host
computer, and transforms them to dots on a page that the RIP (Raster Image
Processor) in the printer converts to the printed page. The device you are
posting will only work when connected to the printer part, and can not serve any
other printer. I wish I has one of them today, wonderful system, I remember
exactly how each board in the ESS worked and why. Phil Shaw (above) is right
about the CP/M file format, but the rest is proprietary Xerox hardware made on
777 S. Aviation Blvd. El Segundo. USA. Software was written in a variant of C++
and Assembler.


Ole Sandner