At 12:46 PM 11/7/97 -0000, you wrote:
>There have been one or two suggestions lately to interface a PIC to PC
>ISA cards.
>
>Has anyone ever done this ?

Yes, I did it several years ago.  It started when I needed a small portable
unit to demonstrate a PC I/F card I sell.  I was tired of hauling around a
luggable PC. The design won "best cost improvement" catagory in a Microchip
design contest a few years ago.

>Is it simply a matter of generating the relevant bus signals etc?

Pretty much.  I started out using the same clock freq that the ISA bus clock
runs at, 14.?? MHz. That made timing easier.  Even then I had to put some
NOPs in because the PIC was too fast!

Interrupts were a problem since I was using the PIC16C55. I had some
external hardware and polled it with the PIC.  With newer PICs you could
implement true interrupts.

I developed a commercial design based on all this. Its in the Microchip
Third Party Guide. Contact me direct if you are interested.



------------------------------------------------------------------------
Gary Sutcliffe,  W9XT          Unified Microsystems
ppvvpp@mixcom.com              PO Box 133 Slinger, WI 53086
http://www.qth.com/w9xt        414-644-9036