[W/K] :: software rot

  software rot 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     program's assumptions become out of date.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.
     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.
  
  

  software rot
       
           The tendency of software that has not been used
          in a while to fail; 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          when a program's assumptions become out of date.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 shortsightedness in the design of some
          COBOL programs, many would have succumbed to software rot when
          their 2-digit year counters wrapped around at the beginning of
          the year 2000.  A related incident made the news in 1990, when
          a gentleman born in 1889 applied for a driver's licence
          renewal in Raleigh, North Carolina.  The 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 initialisation
          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.
       
          [{Jargon File]
       
          (2002-02-22)