1. The computer you exclusively use for watching pornography.
2. A computer which, due to circumstances, is useful for nothing other than watching porn (likely due to watching too much porn on it in the first place).
"I re-appropriated my laptop as my pornocom. It's slow as hell and can't run anything well anymore. It's good for nothing but porn."
"I watched so much porn on this computer, I can't use it for anything else. It even smells musky now, so I can't even bring it out in public. It's now my new pornocom.