Another point if we are going to use different families such as the AT89C52 or the P89C51RD2 dont we need different emulators? I dont know.

The Ceibo EB51 series is somewhat unique in the respect that it does not use bondout chips. This does, indeed, remove the possibility for the 5% of emulator features you would use 1% of the time. However it has the advantage that, if you want to emulate another derivative, you just replace the emulator chip with the one you want to emulate. I frequently pop another chip into my Ceibo, so far I have used it with 80c51, 80c32, P89C51, P89C66x, Winbond 516 and more.

Erik