You should consider looking closely at the 8051 type parts from Cygnal. You can get evaluation boards that are quite inexpensive. Each and every Cygnal part has on board hardware that is accessed via a JTAG port, This special hardware supports code breakpoints, peeking at and modifying processor registers, single stepping and some other operations that are similar to what you would have to pay several thousand dollars to get in an emulator unit.

The best of all is that since this JTAG accessible debug support hardware is on every chip it also goes right into your target product. If you provide JTAG access from your target board it is then possible to do code tracing, breakpoints, and single stepping right in the field or at the end application location within the target hardware environment.

Read all about it at http://www.cygnal.com

Michael Karas

(No I am not affiliated with Cygnal in any way other than as a user of their products. I have purchased numerous evaluation boards from Cygnal and designed in and coded for 4 or 5 different flavors of their parts. If you visit my 8052.com home page at http://www.8052.com/users/mkaras/ you can read several articles I have posted where Cygnal products are mentioned).
MJK