Yes that Dallas 8051 is pretty fast. With just the software PWM loop running, the output to both motors is around 15Khz.

From Andy's last post it was clearing up a few things in my head as to what happens in the INT, and I'm seeing now that I can't simply expect to grab all three bytes in one INT jump.

I was thinking that I'll need some type of way to grab one byte and return from the INT, and on the next call, grab the next byte to the next register.

On another note, I've never really had any problems using registers for my programs because I remember and notate what each one is to be used for, however I'm used to looking at R1-R7 as regular variable space, I suppose a bad habit to get into down the road. How do you guys do it? Assuming the Dallas 8051 I use starts with direct RAM at &20h, can I simply use MOV &20H, data to store a byte there? Sorry, never did it that way before :-)

I thought I would show you all what I've done.
http://www.geocities.com/adempha/ss.jpg < screenshot of the app used to control this (hopefully soon anyway) Box with green lines shows the current image which would be displayed with the laser. Thats the standard laser test pattern everyone uses.
http://www.geocities.com/adempha/projector.jpg < Closeup of the laser module, two motors with mirrors.
http://www.geocities.com/adempha/system.jpg < Complete system showing the 8051 board as well as projector. I added a fan over the voltage regulator to cool it because after the motors and laser module were connected it started to get relatively hot. Two chips on the left are a Max 233 and a 74241 for interfacing the serial port to the 8051. The chip above the 8051 is an 8 channel serial ADC, which you guys will never believe, but I wrote some code for it and it worked on the very first try using a "bit banging" method. Like I said in an earlier post, this board was to eventually be used for a robot I was building.