The Ghost in the Machine

Many years before the invention of new-fangled protocols like TCP/IP (which is the networking protocol on which the internet runs), IBM mainframes had powerful networking capabilities, largely run by a piece of software called VTAM (for Virtual Telecommunications Access Method).  VTAM is still in use in high-end installations today, and allows the mainframe to drive huge networks of terminals, printers and other devices.

On large systems, it used to run on a separate machine called the IBM 3745/3746 Communications Processor.  If this came down for some reason, it meant that the network was completely unavailable, although the mainframe itself might well be running normally.

Under these circumstances, the only way of communicating with the mainframe was via the operator console, a special terminal in the computer room which is channel-connected, i.e. it bypasses the network and is connected directly to the mainframe.

However, the computer room console was there for the machine operators.  The expert systems programmers who had to resolve the problem usually logged onto the machine from the terminals in their offices, which typically went via the network.  The sysprogs could issue console commands (direct commands to the mainframe operating system –  a bit like command-line DOS) via software like TSO or Roscoe, and also edit system parameters and do whatever was necessary to fix the problem and get the machine running smoothly again.  But if the network was down they couldn't connect to the machine at all, and would have to go and work at the console in the computer room.

So it soon became common practise to install one or two channel-connected terminals in the offices of senior systems programmers, so that they could connect directly to the mainframe even if the network was unavailable.

Dad, as Systems Support manager, was the first to receive one of these at SCS.  One Saturday night, needing to do some work on the machine after all the weekend jobs had run, he drove into work at about 1am, went straight to his office and logged on.

He started up a TSO session and started issuing console commands to do whatever it was he needed to do.

Moments later, he heard a shriek of terror, a door slammed, and running footsteps hurtled past his office and into the foyer.

The operator on shift, who was fairly new to the job, had seen Dad's console commands, apparently coming from nowhere, repeating on the operator console in the computer room.  The mainframe, he had decided, was haunted, and he fled.   

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