[sdiy] So what's the difference between these IC's?

[mirwin at qouest.net]

Don Lancaster mentions this regarding the CD4030 vs. CD4070 (from CMOS 
Cookbook, 1st ed.)

"early versions of this device have a very LOW input impedance and 
behave erratically in pulse circuits - use the 4070 or equivalent 4507 
instead".

This might have been a result of the input protection network used on 
this particular device(?)

Now, looking through the RCA 1980 COSMOS databook - there is no mention 
of this and the input specs are similar for both the 4030B and the 
4070B.

Also - for "A" series, the abs max supply voltage is 15 V... while the 
"B" series is 20V. "A" series recommended operating supply voltage is 3 
to 12V, while "B" series is 3 to 18V. Good idea NOT to use "A" series at 
15 volts... use "B" instead. 4000 series preceded the 4000A series and 
had even lower ratings.

Also.. for "B" series... both the 4030B and 4070B have the same abs max 
supply voltage rating. (there is no 4070A listed in this databook to 
compare with the 4030A, perhaps it was introduced with the "B" series)
This is from the RCA databook, other manufacturers may have different 
ratings.
Regards, Mike