Local registers on HP-41?

[Ángel Martin]

A similar concept to these local registers is already implemented in the Total_Rekall module. There it is called the "shadow stack or emergency buffer" and provides 5 data registers for data storage and recall. Dedicated prompting functions are bRCL, bSTO, bX<>, and bVIEW with allowed values from 1 to 5.

This buffer is also used for other purposes, like stack shuffle-selective delete, and subroutine RTN stack extension....