Big Red Switch: n. [IBM] The power switch on a computer, esp.
the `Emergency Pull' switch on an IBM mainframe or the power
switch on an IBM PC where it really is large and red. "This !@%$%
bitty box is hung again; time to hit the Big Red Switch." Sources
at IBM report that, in tune with the company's passion for TLAs,
this is often abbreviated as `BRS' (this has also become established
on FidoNet and in the PC clone world). It is alleged that the
emergency pull switch on an IBM 360/91 actually fired a
non-conducting bolt into the main power feed; the BRSes on more
recent mainframes physically drop a block into place so that they
can't be pushed back in. People get fired for pulling them,
especially inappropriately (see also molly-guard). Compare power
cycle, three-finger salute, 120 reset; see also scram switch.
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