An Evening With Assembly
Back when I was young child, my brothers and I used to play a game called Moonstone. So it was with a bit of nostalgic glee that I went about spending a few hours or so in evening poking around the innards of the game. I wish I had bothered to take a look at the time, as I managed to remove the unbelievably long, unskippable intro that the game has, which would of saved my brothers and I a few hours of pain, enduring the intro whilst waiting for the game to start. You can find the game itself on various abandonware sites and it runs fine in DOSBox. The game comes with three executables, MS.EXE (the executable to play the game), INTR.EXE (the executable that runs the intro sequence) and MAIN.EXE (the main game itself). DOSBox has a debugger build that allows you to examine memory, step through execution, set breakpoints and more. There's a guide to help you along. The freeware version of IDA, thankfully supports dos exes, so I could open up all three to have a poke around.