Restoring classic kits we built way-back-when

From: Michael Holley <>
Date: Fri Oct 5 00:18:32 2001

I build a replacement floppy disk controller card for SWTPC 6800 / 6809
computers. The original controllers were build from around 1977 to 1984. The
first goal was to make it software compatible. A secondary goal was to
duplicate the technology of the early 1980s. After working on it for a few
months I decided to use a programmable logic device from 1991. This reduced
the cost and made the design much more flexible. I would have liked to use
all 1980s technology but the newer CPLD made the design much better.

The Xilinx XC9572 CPLD is based on the Plus Logic 2020. I have an
engineering sample of the 2020 with a 9118 date code.

I did put the date (July 2001) on the board.

You can see the design here.

Michael Holley
Received on Fri Oct 05 2001 - 00:18:32 BST

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