n. Term used to describe the tendency of software
that has not been used in a while to lose; such failure may be
semi-humorously ascribed to bit rot. More commonly,
'software rot' strikes when a program's assumptions become out
of date. If the design was insufficiently robust, this may
cause it to fail in mysterious ways.
For example, owing to endemic shortsightedness in the design of
COBOL programs, most will succumb to software rot when their
2-digit year counters wrap around at the beginning of the
year 2000. Actually, related lossages often afflict centenarians
who have to deal with computer software designed by unimaginative
clods. One such incident became the focus of a minor public flap
in 1990, when a gentleman born in 1889 applied for a driver's
license renewal in Raleigh, North Carolina. The new system
refused to issue the card, probably because with 2-digit years the
ages 101 and 1 cannot be distinguished.
Historical note: Software rot in an even funnier sense than the
mythical one was a real problem on early research computers (e.g.,
the R1; see grind crank). If a program that depended on a
peculiar instruction hadn't been run in quite a while, the user
might discover that the opcodes no longer did the same things they
once did. ("Hey, so-and-so needs an instruction to do
such-and-such. We can snarf this opcode, right? No one uses
it.")
Another classic example of this sprang from the time an MIT hacker
found a simple way to double the speed of the unconditional jump
instruction on a PDP-6, so he patched the hardware. Unfortunately,
this broke some fragile timing software in a music-playing program,
throwing its output out of tune. This was fixed by adding a
defensive initialization routine to compare the speed of a timing
loop with the real-time clock; in other words, it figured out how
fast the PDP-6 was that day, and corrected appropriately.
Compare bit rot.
