Conversations you wish you hadn't had, number 44. Gingerly entering the lift, I find it contains a cheery bloke in overalls. He's going to our floor -- we've got the builders in, so I ask "You here to sort out the partitions?" "Nah, mate. Lifts." Aha. "Good," I say, "They need it." I recount yesterday's exciting lunchtime treat. "Yeaaaah," he says, thoughtfully. "They do that. These lifts are fine, it's the controllers that are the trouble." There are basic rules to having conversations like this: if you find yourself on a plane sitting next to someone leafing through Aircraft Mechanic Monthly or Explosions At Altitude - The Mystery And The Carnage, it's best to keep to yourself. But nobody's told me, so I plough gamely on. "Controllers?" I say, and do the "let's drop a technical term in to seem as if I know what I'm talking about" tack. "Are they solid state on this installation?" "Hah! That's the thing. They're relay logic." Relay logic, distant reader, is a kind of clockwork computing of roughly the same vintage as the kind of telephone exchange that made 'dukka-dukka-dukka' noises when you were trying to get through to Dial-A-Disc. Even BT's scrapped relay logic by now. "No wonder they don't work!" I said. "Is it ever going to be upgraded?" "Oh, could be." he said. "The building management had a meeting yesterday to decide whether to put in a solid state replacement." "That'll be better" I said. "Yeah. Solid state works fine most of the time. But when it goes wrong, it really, really goes wrong. Gotta go. Bye!" And he vanished into a small door I'd never seen before. See what I mean? Doctor says I need more exercise. Stairwell, here I come. Click here to see more of Rupert's diaries.