QtSPIM
STEP 1: Download QtSPIM in your directory.
http://spimsimulator.sourceforge.net/

STEP 2: After the simulator is installed, run the simulator from START/PROGRAM/PCSpim for
Windows/PCSpim for Windows.

SPIM Instruction Set

Hello World - Sample Code
Display - Sample Code
Add - Sample Code (This takes in a number from the user and adds 5 and displays the result back)
Verilog

Tutorial

Xilinx, ISE WebPACK

Overflow