At 10:54 AM 12/9/96 -0600, you wrote:
> You must be careful subbing 74 series parts here for CMOS.  This device
>is powered
>by stealing power from the Printer Port by using data output lines to
>charge a cap.  Therefore VCC will never be a true 5 volts.  Depending on
>the PC, this stolen VCC will always be less than
>5 volts, it could fall as low as 3 volts on some PCs.  That is the reason
>the author/designer
>chose to use CMOS devices, because they can function on this lower
>voltage.  74HC parts require a good solid 5 volts.

I haven't checked my data book yet, but I thought the 74HC parts were CMOS
and could handle the lower Vcc.  The other 74 series may be a problem (i.e
Plain, LS, etc.).  I plan to add a power supply for the 5VDC anyway.  I'm
not a big fan of stealing power from the port.

Norm