Erlkönig: drum-explanation.shtml

From: curt@cynic.wimsey.bc.ca (Curt Sampson)
Subject: What is /dev/drum?
Date: 31 Jan 91 00:30:08 GMT

whelan@huey.uhcc.Hawaii.Edu (The Obscure Guru) writes:

> 	I was recently perusing the /dev directory on a next
> when I came upon the entry /dev/drum.  This seemed a bit odd, I thought
> that drum memory went out of fashion long, long ago.  The man pages
> didn't have anything to say about drum.  Does any have any insight
> on this odd device entry?

This actually has nothing to do with drum memory.  It's a part of the
UUCP system.

Long, long ago, even before version 6, somebody wanted to implement a
program to copy files between two machines running Unix.  At the time
there were no modems becuase there weren't even any telephones.  A
Bell Labs researcher who had just visited Africa seized upon the idea
of communicating by beating on drums, as the native Africans did.  He
added a drum interface to his PDP-11 and the device driver was called,
of course, /dev/drum.  Uucp would call a lower level program called
`bang' to activate this device driver.  Messages could also be sent
manually by typing `bang drum' at your shell prompt.  People soon
devised shell scripts that would take a mail message, convert it
appropriately, and call bang to send it.  Soon they were sending
multi-hop messages though several sites this way, which is how the
`bang path' got its name.

With the advancements in communications technology (semaphores in
particular), /dev/drum was removed from UNIX around version 6 or 7, I
believe.  The NeXT developers reinstated it on the NeXT because they
felt that a true multimedia machine should have as many options as
possible.

I hope this explanation helped.