I never had a HP65 but it was what my HP67 was based on and wow it looked like a great calculator.
The keyboard layouts were very similar too.
The f, f-1, and g keys became f, g, and h.
There was extra writing added because the new g key was no longer labelled f-1 :
– on the HP65 f 9 was square root, f-1 9 was un-square root i.e. square
– on the HP67 f 9 was square root, g 9 was square
It was no longer obvious so HP added x2 next to the square root sign.
The writing also moved from above their keys to below their keys.
Aside from a few minor changes on the second row, the keys remained in familiar positions.
You can see a HP67
So, why did people upgrade from the HP65 to the HP67?
There were lots of really good things about the HP67 and just as many reasons. A couple of obvious ones were: more memory and bigger programs. But, for many, these weren’t reasons to ditch the great HP65 – merely reasons to get a HP67 too.
