Re: timer circuits

Another question born of ignorance :o)
If the choice of timing is the on board timer or subroutines,wouldn't a
standard clock, crystal controlled pulse generators can be made real cheap,
be added somehow to one of the I/O's to give a timing standard that could be
used by all? And maintain a consistent speed in case you changed computers?
Not sure if I asked that correctly or not. A little information is a
dangerous thng :o)
Tracey