cctalk Digest, Vol 35, Issue 9

Earl Baugh earl at
Tue May 9 12:15:23 CDT 2017

> Date: Mon, 8 May 2017 21:02:39 -0400
> From: william degnan <billdegnan at>
> Subject: Re: BETSI Expander for the Commodore PET
> On Mon, May 8, 2017 at 8:35 PM, John Ball via cctalk <
> cctalk at>
> 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.

BTW, I spoke with Don over dinner after the show and he told me that his
son apparently
archived some stuff when he moved out to NV (he had told me earlier that
most of his
machines got sold/trashed/lost  during his divorce ).  I particularly asked
him to look for
one of the S100 expansion boards...  Will let you know if he found any...


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