For simulator check left side of this site,
For emulator, you can built your own interface from cpu board to Pc serial port and write some code to see the status of different registers inside the cpu and txnmt to Pc via serial port. It is not simple but can be achieved.
You can read a book from Myke Predco, he described a full fledged Emulator for 89C2051 in his book "customizing and interfacing 8051".

goodluck

Rauf