This is my implementation of a 6502 CPU simulator written in C#. It simulates a basic 6502 processor and memory. It also has an application written in WPF that functions as a test harnesss and allows you to load a program into memory and step through the program, set break points, and watch the various registers. This project is now feature complete. It successfully passes all of Klaus Dormann's tests including the IRQ tests. Feel free to submit bug requests if you find an edge case! Version History .0.9.9 All OP Codes Implemented. .1.0.0 All of Klaus Dormann's Tests pass successfully. I used the following websites during implementation as a reference http://visual6502.org/wiki http://homepage.ntlworld.com/cyborgsystems/CS_Main/6502/6502.htm http://www.atariarchives.org/alp/ http://en.wikipedia.org/wiki/MOS_Technology_6502 http://www.obelisk.demon.co.uk/6502/ http://www.6502.org/tutorials/ I used the following test programs to validate the simulator. http://2m5.de/6502_Emu/ Klaus Dormann 6502 Test Suite (GPL License) How to Compile Tests - Go grab the AS65 Compiler http://www.kingswood-consulting.co.uk/assemblers/ Modify the 6502_functional_test.a65 load_data_direct = 0 Run the following command to generate the bin file and lst file as65 -l -m -w -h0 6502_functional_test.a65 In the simulator Load the test Set the Memory Offset to be 0x0400 and the PC to be 0x0400. Program Listing starts at 400