Yes Steve, I understood what you said. But I read somewhere that there are some derivatives whose has special register to hold uP's self address, and upon receiving address bytes, compares it with its own address, if both mataches, means the comming data should be received otherwise ignore it.
I dont think it is possible with 89C2051 or 89C52. I havent check the data sheets of the uPs what Jay have mentioned. I will check their data sheets and will let you know.
Thanx
Rauf