The Y2K38 problem has been described as a non-problem, given that we are
expected to be running 64-bit operating systems well before 2038. Well, maybe.
Just as Y2K problems arise from programs not allocating enough digits
to the year, Y2K38 problems arise from programs not allocating enough
bits to internal time.
Unix internal time is commonly stored in a data structure using a
long int containing the number of seconds since 1970. This time is
used in all time-related processes such as scheduling, file timestamps, etc.
In a 32-bit machine, this value is sufficient to store time up to
18-jan-2038. After this date, 32-bit clocks will overflow and return
erroneous values such as 32-dec-1969 or 13-dec-1901.
Currently (March 1998) there are a huge number of machines affected.
Most of these will be scrapped before 2038. However, it is possible that
some machines going into service now may still be operating in 2038.
These may include process control computers, space probe computers,
embedded systems in traffic light controllers, navigation systems etc.
etc. Many of these systems may not be upgradeable.
computers survived in service longer than anyone expected; long enough to present
serious maintenance problems.
Note: Unix time is safe for the indefinite future for
referring to future events, provided that enough bits are allocated.
Programs or databases with a fixed field width should probably allocate
at least 48 bits to storing time values.
Hardware, such as clock circuits, which has adopted the Unix time convention,
may also be affected if 32-bit registers are used.
In my opinion, the Y2K38 threat is more likely to result in
aircraft falling from the sky, glitches in life-support systems,
and nuclear power plant meltdown than
the Y2K threat, which is more likely to disrupt inventory control, credit
card payments, pension plans etc. The reason for this is that the
Y2K38 problem involves the basic system timekeeping from which most
other time and date information is derived, while the Y2K problem
(mostly) involves application programs.
Emulation and Megafunctions
While 32-bit CPUs may be obsolete in desktop computers and servers by 2038,
they may still exist in microcontrollers and embedded circuits. For instance,
the Z80 processor is still available in 1999 as an
within Altera programmable devices. Such embedded functions present a serious
maintenance problem for Y2K38 and similar rollover issues, since the package part
number and other markings typically give no indication of the internal function.
Databases using 32-bit Unix time may survive through 2038. Care will have
to be taken to avoid rollover issues.
Y2K related links