To generate pwm at a higher frequency I can use a processor with automatic pwm generation but I can't find one that does this on P1.5 with 16-bit resolution for the duty cycle (yes, I actually need this) and which is a drop-in replacement so it will work on my current board. ... PLCC44 drop-in replacement.

PCA module2 will drive P1.5 for both the P89C51Rx2 and the P89C66x.
Both are 6clockers up to 20Mhz or 12 clockers up to 33MHz, but both can drive the PCA at fosc/2 in 6 clock mode(fosc/4 in 12 clock mode). This will give you up to 100ns resolution.

Have a look, you can find the datasheets (for this feature, almost identical, if you can use one, you can use the other) in linkds<--- at Philips appnotes (yes data sheets also) under "interesting sites"


Erik