HP-75 Designations?

[J-F Garnier]

(12-28-2020 02:27 AM)toml_12953 Wrote:  I see ads for HP-75 C and D. Are there only those two? What are the differences? Which is the most powerful of the HP-75 line or isn't there a difference in that regard?

More important than the 75C/D labelling is the ROM version.
The ROM version can be obtained with VER$ but is rarely mentioned in ads.
There are basically 4 versions: aaaaaa , bbbbbb , cccccc , dddddd.
although it existed some mixed versions like bababa.
The latest version dddddd is preferable.

Moreover, there is no simple correspondence between the 75C/D variants and the ROM versions, there are examples of 75D with ROM aaaaaa or bbbbbb although you have better chance to find the dddddd ROM in a 75D.

J-F