Sean: Random button mashing! Actually I figured it out by accident, since I read that Michael Gray had a secret mode in omega virus (which I later read the exact sequence to activate elsewhere) I wondered if there was some sort of hidden secret game in battleship if you held down a pair of buttons; so I held down both a1 and b2 when powering on the game, and it activated the key test mode (which is very weird behavior compared to the way the game normally starts). Immediately I tried holding just b2, and got the sound test, then just a1 and got the key test again (so the game must read the keys starting from a1 toward j10 in sequence; this turns out to be true for omega virus as well).
Omega Virus arrived yesterday and I wondered if it had similar tests, and sure enough first try holding 0 down did the key test, and second try holding 1 down did the sound test.
"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"