Mainframe madness as the snowflakes take control – and the on-duty operator hasn't a clue how to stop the blizzard

Each one unique, and they'll keep coming till there's no paper left... or someone kills the power

Who, Me? Another week means another tale of reader misdeeds in The Register's ongoing Who, Me? series.

College-based antics appear to be a thing, based on the content of our inbox, and today's confession takes us to a Canadian technical college in the 1970s.

As the age of the personal computer was dawning around the world, "David" (which is not his name) was working with a Xerox mainframe, replete with teleprinters to input code and punched paper tape on which to save programs.

A curious fellow, David discovered the model name of the mainframe in use on campus and, keen to hone his skills, ordered the full programming manual from Xerox. It was, he said, "a goldmine of ways to program better."

It got to the point where David and his pals not only churned out impressively tight code, but they also understood the inner workings of the hardware better than their instructor. "He had only basic knowledge," sniffed David.

As with so many campus-based shenanigans, it did not end there.

"We discovered, hidden in the deep recesses of the manual, a way to bypass some basic controls and actually control the mainframe directly."

Armed with their newfound skills and some usernames and passwords liberated from discarded TTY print-outs, the gang headed into the lab to try out their work.

It all sounded innocent enough: "Our program was a variant of the snowflake program found in the manual."

How lovely – a simple snowflake would be spat out by the TTY.

"We had the mainframe output the snowflake at every TTY machine on the entire campus. And each snowflake was unique. No duplicates. It would keep printing snowflakes until it ran out of paper or was stopped."

A 10-minute delay was added to allow David and his pals to scarper before the insanity began. "Since it was told to make sure each snowflake was unique it took up most of the computing power available," he added.

A perfect plan – except, as David ruefully admitted, "what we did not know was the operator for that day in the IT department had no idea how to stop it. None whatsoever."

For 30 minutes the program ran, burning through CPU time and spewing snowflakes. Not knowing what else to do, the panicked operator killed the power supply, stopping the program but causing all manner of other bad things to happen to the mainframe.

"If he had read the same manual we bought," said David, "he would have known how to create a master interrupt to stop the madness."

Access to the mainframe remained verboten for three days after the incident. When the ban was lifted, David discovered that the access he'd managed to get was now restricted to terminals in the same physical room as the mainframe itself.

Their method of nabbing usernames and passwords was also stopped as The Powers That Be realised that echoing logins on a printer was probably not a good idea. A sign-in and sign-out policy for the labs was adopted and access to the commands used to hijack the campus printers were also restricted.

The snowflake gang was never caught, and doubtless whiled away the years that followed chuckling about their prank over a bowl of poutine and a growler of ice beer.

Ever had your curiosity get the better of your instructors or sent a server into a tailspin of distress, but nobody ever knew it was you? Now is the time to confess all, with an email to Who, Me? ®