Are there any good open source frameworks for developing computer system emulators? I am particularly interested in something written in Python or Java that can reduce the effort involved in developing emulators for 8-bit processors (e.g. 6502, 6510, etc.).
Isn't the 6510 in the C64? You might be able to make use of the java libraries that emulate c64 code
http://www.dreamfabric.com/c64/
http://www.jac64.com/jac64-java-based-c64-emulator.html
If you aren't afraid of C++ try this general purpose one: