The original 80386 S100 bus CPU board has worked well in most S100 bus systems up to around 8MHz for PHI. In an effort to construct an equivalent 80486 CPU board it became apparent that I would have to utilize a CPLD such as the Atmel ATF 1508:-
http://s100computers.com/Software%20Folder/CPLDs/Amtel%20ATF1508.pdf
to get everything to fit on one S100 board.
Programming CPLD’s requires a slightly different programming language (Wincupl) .
In order to ease the transition from an 80386 to the more complex 80486 S100 board I decided to first fabricate a CPLD based 80386 board. The first prototype of this board is described here:-
http://s100computers.com/My%20System%20Pages/80386%20Board/80386%20CPU%20Board.htm#CPLD_80386
This board appears to be much more stable on the S100 bus reaching speeds of 10MHz and 40MHz in protected mode.
This is just a status update. A second board (as well as my first 80486 board), is in the works.
Stay tuned.
John