A brief description of my work is as follows,

The embedded control system consists of a personnel computer, three identical microcontrollers and three stepper motor drivers.
The personnel computer is connected to one of the microcontrollers through a serial link. This microcontroller is the master subsystem and all other microcontrollers are slave subsystems. The master subsystem can send data to slave subsystems through the data bus. Similarly it can receive data from the
slave subsytems. But slave subsystems have no privilege to access the master's data bus.

A stepper motor is connected to each microcontroller. Stepper motor is used for
moving an axis, which is attached to it. The microcontroller can also receive feedback from an axis driven by it, in the form of limit or home switches. In addition to the motors, each microcontroller can also control a set of switches. These switches are used for turn on/off and open/close operations for lamps, shutters etc.

I can't kept my whole code in external ROM
because interprocessor communication is through the data bus. So i need ports P0 and P2 for that. I am planning to keep only some sections of my program, which takes place inside the system, in external ROM. Important routines like Command receival, command trasfer, command parsing are kept in internal ROM.

My task is to create an OS for a h/w and I don't know much about the h/w section. I studied about the existing system for one month. So plz read the description and I am expecting your questions about it. I think this will make me to think about those thing which i didn't encountered.

Prasad