Notes on  SOFTWARE ROT 

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assumptions become out of date.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. Syn. code
rot. See also LINK ROT.

For example, owing to endemic shortsightedness in the design of COBOL
programs, a good number of them succumbed to software rot when their
2-digit year counters underwent 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.

J3N Research Labs

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