The PDP-10 had an alarm bell that could be rung under program control.  When the TOPS-10 operating system crashed, it displayed a numeric code on the console indicating the reason for the crash.  This was called a "stopcode" and is the equivalent of a Unix panic.  It also rang the alarm bell.

DDT (Dynamic Debugging Tool) was the primary debugger for TOPS-10.  PPN (Project-Programmer Number) was used for system security.  Each user account was assigned by number to a Project, and within that Project a unique Programmer Number.  The low numbers (such as [7,3]) were usually privileged accounts.

So here we have the Christmas carol Stopcode Bells, to the tune of Jingle Bells:

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Stopcode bells, stopcode bells, stopcode all the way.

Oh what fun it is to crash the system night and day.

Stopcode bells, stopcode bells, stopcode all the way.

Oh what fun it is to crash the system night and day.

Poking through the core

With a bug in DDT

Change your PPN

To [7,3].

Halt somebody's job.

Make them scream and shout.

Oh what fun it is to log

The operator out.

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This is one that I wrote while I worked in DEC's software development tools department.  Around Christmas time the first baselevels of VAX/VMS Version 3.0 were being sent to alpha test.  The engineering departments got first crack at the new system and so were the first to encounter bugs and design problems.  VMS Version 3 had been a very ambitious project and was eventually split up into Version 3A (released as Version 3.0) and Version 3B (released as Version 4.0).  There was a lot of grumbling by groups whose new features got put into 3B and thus delayed.  The early baselevels of 3A broke the VAX C runtime library.

So here we have Version 3 is Coming to Town:

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You'd better work hard

You'd better code fast.

The system you use

Just ain't gonna last.

Version 3 is coming to town.

They fixed some old bugs

And put new ones in,

Added some features

They think will win.

Version 3 is coming to town.

There's so many new features.

Too bad we can't use C.

And the things that we most wanted

Were deferred until 3B.