Local registers on HP-41?

[David Hayden]

At HHC-2016 Gene gave an update on the HP-41CL. He also mentioned the NoVRAM alternative.

One thing that they both seem to have in common is a lot of available registers. I've often thought that *people* don't need extra registers, but *programs* do.

The WP-34S has the concept of Local Registers and flags (see "Local Data" beginning on page 69 of Edition 3.1 of the WP-34S Owner's Manual). In summary, a subroutine can allocate n local registers by executing LOCR n. Thereafter the registers are available and registers .00, .01, etc. If a new subroutine calls LOCR, then it allocates a different set of local registers. When a subroutine executes RTN, the local registers are deallocated.

So here is my question/challenge: would it be possible to add local registers to the 41C? I imagine that no opcodes are available, so the STO/RCL functions would have to be individual library functions (XROM calls? It's been a while...). The memory for the registers would be allocated in bigabytes of memory on some of these cards.