searching for replacement for 1793 FDC

-----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 -------------------------------