Infidel goes wild

Planetfall was yesterday's public release, but of course I've spent the past few weeks concentrating on Infidel. A couple of days I came across the most egregious bug I've yet seen in an Infocom game. This bug is extremely difficult to detect by playing the game. I must the first person to notice it, just because I'm the first person to play the game with (the equivalent of) a memory-level debugger. So why do I call it an egregious bug? Most people would call it a "trivial" bug, since it almost never impacts gameplay. But look you: it's a wild pointer bug which scribbles over memory in an unintended way. As a C programmer, I am legally required to regard memory corruption as the worst of all possible sins. On top of that, it's a compiler bug! (Warning: This will get into ZIL code and Z-machine implementation details. Note that I will be analyzing Infidel release 22 serial 840522, the update for Macintosh. The original release, serial 830916, has the same bug with slightly different…