TKGate (http://www.tkgate.org/ http://www.tkgate.org/) is an awesome visual tool for discrete logic simulation, and comes with a toy processor as an example cir

TKGate (http://www.tkgate.org/ http://www.tkgate.org/) is an awesome visual tool for discrete logic simulation, and comes with a toy processor as an example circuit. I implemented a simple 32-bit MIPS-like processor in TKGate as well as the DLX architecture from Hennessey and Patterson. I also designed and implemented my own microcoded 8-bit processor for variety. That project eventually included bootstrapped assemblers and disassemblers, and an emulator in C for faster simulations. Here's some of my TKGate work: http://xidus.xidus.net/mips http://xidus.xidus.net/mips Check out TECS/NAND2Tetris to get started with VHDL and processor architecture: http://www.nand2tetris.org/ http://www.nand2tetris.org/ If you want a more academic approach, try Hennessey and Patterson's Computer Architecture: A Quantitative Approach.