HP11C ++

[J-F Garnier]

No need to move chips.
Since this 20-years old post, we got "true emulators" (meaning: that use the genuine ROM), starting from Nonpareil (well, it didn't use the "genuine" ROM but that's not important here).
And the result is: nothing happens if you plug more RAM registers.

To make the 15C ROM use the extra registers, several ROM locations must be changed (patched). SwissMicros and a few others did it.
I'm not aware that it has been done or is even possible with the 11C.

My hypothesis about the special 11C mentioned in the original post: it may be a HP-15C board mounted inside a HP-11C housing.
Since the 11C and 15C keyboards are very similar, it may give the impression, with just a quick inspection, of a 11C with 448 program steps.
Of course I may be wrong.

J-F