Fantastic Dan!

I just tried it out - and it works! I had to reenable ANSI Integer Promotions and it appears to be making the correct output.

The FIR routine runs 40% faster with the 8x16 multiply. This enables me to do a 16 tap, 16-bit coefficient, 8-bit input FIR filter running with 1kHz sampling frequency using a P89C51RD2 @ 32.0 MHz (12-clock).

Thanks Dan, you saved me from doing inline assembly for this. Guess I owe you one.

Is anyone interested in this project? I can post the project (report and everything) when I am finished..

- Lee