This lovely blue one has the 1568 classical steps in standard version (with 1kb on the motherboard) bue has a location for an extra memory extension.
RAM : 2392 / 2392 steps with extension memory OR-20.
The insertion of a OR1 doesn't change the memory, 1568 program steps,
Stange, it accepts an OR-20 2ko-extension memory released for Data Bank models (not programmables) like PF-3000 and then has 2392 program steps, what is 1 kb more than in standard version.
In fact, it seems that, for that model, the extension memory replace the standard memory on motherboard. A 1kb extension memory doesn't change anything, a 2ko extension memory adds 1ko.