SBS said:
Do I really need to isolate the two oscillator circuits or can I
connect them as I have written above?
If I would have to use another logic chip, then I may use 2
crystal for an even better solution, don't I?
There are two problems to solve to use a single crystal to
drive two chips. The two inputs may not settle to the same
DC bias voltage. And the extra load of the second chip may
slightly affect the first. You solve the first problem by
coupling the output of the first oscillator to the input of
the second. You will have to find out by trial whether the
chip actually connected as an oscillator is loaded too much
by having its output coupled to the input of the second chip.
A problem free way to drive both chips from a single crystal
would be to build an independent oscillator with the crystal
and a cmos inverter, or use a canned oscillator. Use the
output of either of these to drive both clock inputs. If
the single inverter oscillator, I would capacitively couple
to the inputs to let each chip find its own bias point. If
the canned oscillator with a logic level output, direct
connection will work fine.