Throwback Thursday: Switcheroo

Every possible rookie mistake?

Flashback to the 1960s, when this rookie technician is responsible for servicing a telephone switch. And what a switch it is, remembers a pilot fish in the know.

“Enormous,” says fish. “The switch fills a large room and runs unattended. It’s designed for no more than eight hours total downtime over 40 years. The design is for two identical processors, each of which is itself very reliable, and each of which monitors the other and reboots it if needed.

“Sometimes there’s a hard failure. When that happens, the processor that’s still working runs diagnostics on the other one, prints its findings on the console and sends a message to maintenance headquarters.”

One day that happens, and the rookie tech gets the message. He drives the 40 miles to the switch’s location. Sure enough, one processor is dead and there’s a bunch of diagnostic messages on the console.

Finding the problem is easy — the detailed diagnostic messages lead him straight to the circuit board that he needs to replace. He pulls the board and looks for the part number so he can find an appropriate replacement.

Unfortunately, the part number is illegible.

So, without thinking, he pulls the corresponding circuit board from the other processor so he can read the part number.

That immediately crashes the second processor.

Now tech has a bigger problem — this kind of switch is so reliable that he’s never had to boot one manually, and he doesn’t know how to do it. He picks up the phone to call his supervisor for instructions.

“By this point,” says fish, “you're probably a step ahead of me, and you fully appreciate his horror when there is no dial tone.

“The 40-mile drive back to the office to fetch his supervisor may well be the longest drive of his life.

“The switch used up a good portion of its 40-year downtime allotment during that 80-mile round trip. I do not know how long he remained employed after that.”

Sharky hates downtime. Keep me busy and send me your true tales of IT life at You can also subscribe to the Daily Shark Newsletter and read some great old tales in the Sharkives.

Copyright © 2019 IDG Communications, Inc.

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