🚀 go-pugleaf

> When we leave our PCs on overnight, the date does not always
> change, although the time is kept current.  I have not
> figured out how to duplicate so I don't know exactly why it
> happens only sometimes.

Just a guess, but does it only happen when the PC is not used for
two days (i.e. over a weekend)?

This may not be quite correct, because I don't remember all the details,
but the basic idea is this:  The way DOS keeps track of time
is to increment a counter each time the timer interrupt comes in (18
times per second).  Then the DOS routines convert this to the
actual date and time.  When the timer interrupt notices that a midnight
has been crossed it simply sets a flag - it is the responsibility
of the next call to the DOS time function to notice this flag and
increment the date.  However, if the DOS function is not called for
a whole day (i.e. the time crosses two midnights) the flag will
be set twice but the only noticed (and cleared) once, resulting in
a date that is one day behind.

Peter Fales
ihnp4!ihlpl!psfales