On Mon, May 8, 2017 at 8:35 PM, John Ball via cctalk <cctalk at classiccmp.org>
wrote:
  So it seems in the early days of the PET a company by
the name of
 Forethought Prouducts sold an expansion module called the BETSI which
 plugged into the expansion bus of the PET and gave you four S100 slots. If
 you google around you can find a flyer advertising the unit and optional
 power supply and the owners manual which touches on assembly, component
 locations and the schematics. It talks about adding sound voards,
 additional
 video outputs, expanding ram and attaching directly to a larger S100 frame.
 Beyond that I can find absolutely nothing else about it, much less a more
 recent photo of one. Has anyone here ever used one? How practical were they
 in reality? Suppose I went and built one. Does anyone have the PCB layout
 templates so I could get a board etched or will I have to stick to the
 schematic and build one by hand?
 -John
 
At VCF SE Don French talked about the S100 expansion he created for the TRS
80 Model 1.  Guess these did not meet with much success.