Refer mazidi and mazidi it has details of interfacing stepper motor

As far as my limited knowledge of 51 prog goes if you need accurate timing use assembly and a 12mhz crystal

send data to PC using at 2400 bps connectivity

Do a little research I have spent more than 3 weeks trying to understand communication and other aspects of my project .. still miles to go

See I got a ton of things from google
http://www.google.co.in/search?hl...51&spell=1

Also search robotic sites they will surely have the info

The angle of rotation will depend on number of steps taken by motor ,use a counter to record the number of steps, either you can calculate the angle on the pc or the 51 chip

no of steps x step angle = rotated angle
The direction could be known by setting a bit / clearing it ( 20 -2F in Ram are bit add they can be used for this purpose)as you change the direction

Deepak