The HP-41C always contains a permanent .END. instruction at the bottom of memory. Programs may be ended with the END instruction.
The "last program in memory" is all the space between the last END and the
permanent .END. instruction at the bottom of memory. Pressing
GTO
.. ensures that all programs in memory end in and END instruction and thus
causes any new programs to be loaded after all other programs in memory.
(After
GTO .. the last program in memory is just the empty space between the
END and .END.)
Remember that if you load a program from a card, wand etc. that if you want
all programs currently in memory to be preserved, press
GTO
.. to make sure there is an END on the last program.
Also remember that if you press
GTO
.. between reading several programs, all of these programs will be left in
the memory of the HP-41C. If you want your HP-41C to act more like an HP-65
or HP-67, don't press
GTO
.. and allow new programs to overwrite the last program currently in memory.