HP-65 and HP80 direct reduction loan

[Harald]

I have calculated loan payments with this Program on the HP65 and believe the results to be correct.

However, when attempting to calculate the same using an HP80 I get different results. So I think I am not using the HP80 correctly.
So, if I have a number of periodes, an interest rate, and the annuity, how can I calculate the ammount borrowed?

For example:

I have 12 payments a year for twenty years, 1,9% anual interest rate and 1200 Euros Anuity, on the 65 I would do this:

20
Enter
12
A
1.9
B
1200
D
E
C

What do I do on the 80?

Cheers,
Harald