searching for replacement for 1793 FDC

[Gooijen, Henk]

  Hello Michael,

Thank you for the offer to reuse your design. I already had looked
at it. The chip count is low, and I do not need the CPLD, so there
are just a few parts left!  However, I wanted to stick to my 1973,
because I was not sure about the copy-right stuff.
I will take a few days to think things through and then decide if
I keep the 1793 or move up to the 279x.  The 279x sure saves some
soldering work!

  Thanks,
- Henk.


> -----Original Message-----
> From: cctalk-bounces at classiccmp.org 
> [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Michael Holley
> Sent: vrijdag 2 september 2005 1:58
> To: cctalk at classiccmp.org
> Subject: RE: searching for replacement for 1793 FDC
> 
> I did the FDC design using the WD2797 chip. Anyone can reuse 
> the design as they wish. I have sold out of my original run 
> of these boards.
> http://www.swtpc.com/mholley/DC_5/DC5_Index.htm
> 
> The WD2797 has three adjustment, a capacitor and 2 trim pots. 
>  I used a scope for these adjustment but then made a counter 
> circuit  in the Xilinx CPLD to measure the pulse width. The 
> adjustment procedure is given in the users guide.
> http://www.swtpc.com/mholley/DC_5/DC5_DesignDescription.pdf
> 
> The circuit is in the design description.
> http://www.swtpc.com/mholley/DC_5/DC5_DesignDescription.pdf
> 
> Working with the Xilinx XC9500 series CPLD is easy and they 
> are 5 volt parts that you can get in PLCC packages. (Through 
> hole sockets.)
> 
> Programming them takes a simple parallel port adapter that 
> you can make on a small perf board. I have a small PCB and 
> all of the parts I anyone wants to try to use them.
> http://www.swtpc.com/mholley/DC_5/Cable640.jpg
> http://www.swtpc.com/mholley/DC_5/ParallelCable640.JPG
> 
> -------------------------------
> Michael Holley
> www.swtpc.com/mholley
> -------------------------------