No. We do know, and the consequences of the different connections are spelled out in post #3.

ak

I get it re the board layout, but re divide by 2 last, both the examples I have seen and my own different one divide by 2 last. And what about when we divide by 5 or 25?

 

We are going around in circles.
We do know "It doesn't matter".
In digital electronics parlance, "Don't care" is an expression to mean it is immaterial or "It doesn't matter".

The answers have already been given in posts #2 and #3.
Let us stick with one question.
Instead of considering the multitude of options, what single division do you desire?

 

final question (for now): Why is 2CP0 chosen before 1CP0?

These waveforms show the difference in count sequence when connecting as a BCD (1CP0 first) or bi-quinary (2CPo 1CP1 first) counter:


D, C, B, and A are Q3-Q0 of a '390 connected as a BCD counter. BD, BC, BB, and BA are for one connected as bi-quinary.

As you'd expect, the BCD counter counts from 0-9.

The bi-quinary sequence is 0, 2, 4, 6, 8, 1, 3, 5, 7, 9.

 

...Let us stick with one question.
Instead of considering the multitude of options, what single division do you desire?

No special division required. Just an insight as to how these things work. Thanks all for the inputs.

 

74HC390

Divide by 2:
in: 1
out: 3
gnd: 2,4,8,12,14,15

Divide by 4:
in: 1
out: 13
12-14
3-15
gnd: 2,4,8,12,14

Divide by 5:
in: 4
out: 7
gnd: 1,2,8,12,14,15

Divide by 10:
in: 1
out: 7
3-4
gnd: 2,8,12,14,15

Divide by 20:
in: 1
out: 13
3-4
7-15
gnd: 2,8,12,14

Divide by 25:
in: 4
out: 9
7-12
gnd: 1,2,8,14,15

Divide by 50:
in: 12
out: 7
1-9
3-4
gnd: 2,8,14,15

Divide by 100:
in:12
out: 3
9-15
1-7
4-13
gnd: 2,4,8

 

You are responding to a thread that has had no activity for almost 2 years.

ak

 

Welcome to AAC!

74HC390 [snip]

It would be more helpful if you posted schematics so we can understand what you're describing more easily.

 

Welcome to AAC!
It would be more helpful if you posted schematics so we can understand what you're describing more easily.

http://www.spiratronics.com/data/7660.pdf

What I listed were connections to be made within one, and only one 74HC390 IC.

 

What I listed were connections to be made within one, and only one 74HC390 IC.

I got that, but this:

Is easier to understand this:

Divide by 20:
in: 1
out: 13
3-4
7-15
gnd: 2,8,12,14