Dale, the '7404' oscillator uses the crystal in series mode and besides
not being 'on' the parallel frequency it does not require caps.

The 8085,8051,8052 etc have a larger pin capacitance than many other chips
and they will often run without caps or with only one cap.

In practice a 4MHz oscillator can be 'pulled' about 400Hz without too much
trouble. If it is used w/o caps it may be pulled 200Hz by environmental
factors. If used with caps the environmental factors become a small
percentage of the caps and the pull is reduced to under 10Hz (over
temperature, humidity, etc). That is a 20:1 improvement.

Peter

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