Hi Ghulam

At 19.200Bd, each byte takes 500us aprox. It means 2KHz sampling rate max. with one channel, 8 bits. I think that you should use at least 50Hz sampling rate for ECG. Otherwise will lost information in the QRS part. In that case, and using 14 bits (two bytes per sample), you will be able to sample 20 channels (OK, may be less, I am doing aproximate calculations).

Summarizing, I think that your 8052 would be able to manage this project (may be an one-clocker, like DS89C450). And unless you think in averaging (like related/evoked potentials), you should pay special attention to noise, as previously adviced. And IMHO also think that 14 bits is too much. For complete use of a 14 bit signal, you have to very carefully design board, amplifiers, etc.

Daniel