stepper motor query..

hi friends,
i have to use a hybrid stepper motor(1.8deg resolution) and interface it with 8051.I want to know why and exactly when is a stepper motor controller required.will i require it?and if yes how to decide which one..where can i find help regarding such stepper motor controllers...is L297-L298 appropriate?

You can either use an external controller (with integral motor coil drivers) to switch the coils, or you can just use Power Fets to buffer the Port pins on your MCU to drive the coils more directly, in which case you will have to implement the appropriate phase sequences and possibly phase overlaps ( µstepping) in your code that toggles the port pins.

I have done this using the Parallel Port and some external big NMOS transistors on an old DOS computer

please guide me regarding how to select a stepper motor controller.....and will it reduce the programming?

https://www.electro-tech-online.com/custompdfs/2009/03/3977-2.pdf

WILL reduce programming. check out their whole line if you do not like SMT. I usually reccommend that one since it is step and direction control, microstepping, drive FETS, and synchronous rectification all in one.

Dan