First let me clear up my errors from yesterday.

 A:  Kurt is correct.  The schmitt trigger devices cannot be biased into
the active region to drive a crystal.  So the unused gate cannot be used
for that.

 B: Norm is correct in that 74HC series parts can be used at voltages
less than 5 volts.  However, even though they are speced at these lower
voltages, I have had trouble running at less than 5 volts.  74HC are not
true CMOS.  While they are speced to run at less than 5 volts, they die
at VCC greater than 6 volts.  True CMOS can take up to 15 volts.

As promised, I built a quick version of the device last night.
 1. I supplyed my own +5 volts via a 7805 reg.
  2.  I subbed the 74HC14 for the 40106.
 3.  I subbed a 6 MHZ resonator and moved the divide tap to 12.
 4.  I replaced the RLS4606 diode with 1N4148.
 5.  I ommited the 2.2K resistor pack.

The device is working.  Below are my initial observations.

Speed:

With a Pent. P90, the sample rate is 560nS.  With a 486 DX2-66 then
sample rate is 640nS.  Therefore 1uS or less steps seem to be available.

Software:

This is a DOS utility.  Graphics.com must be loaded to print.  ( Have not
explored printing.)  WIN95 did not like me trying to run Graphics.com, it
generated a "wrong DOS version error".  Running in DOS 6.2, everything
seemed ok.  The Software allows manual trigger, trigger on change (auto),
and a user defined trigger pattern.  After triggering, 5000 samples are
stored.  On my 486 this means the sample window is 3.2mS wide.  User
graphical interface is useable but could use several additional features.
 You have just the scrolling cursor and one placeable marker.  Because
this is making time
measurements via the printer port, I would not advise running this in a
DOS box from any flavor of  Windows.

Conclusion:

While the device has some warts on it.  I can see this type of device
being useful to troubleshoot and debug interface issues like I2C buses,
SPI buses, LCD control interfaces, keyscans, etc.   Though limited, it
only cost me two small ICs,  a 7805, and a DB25 connector.

 ----- Steve