Subroutine Limits - HP -33E Owner's Handbook Manual

68 Subroutines
Subroutine Limits
A subroutine can call up another subroutine, and that subroutine can call
up yet another. Subroutine branching is limited only by the number of
returns that can be held pending by the HP-33E. Three subroutine
returns can be held pending at any one time in the HP-33E. The diagram
below should make this more clear.
Three returns can be pending.
Main Program
line 00 line 09 line 17 line 25
// (esg] 25
\ &=
The calculator can return back to the main program from subroutines
that are three deep, as shown. However, if you attempt to call up
subroutines that are four deep, the calculator will execute only three
returns:
Only three returns can be pending...
Main
Program
line 00 / line 09 line 17 / line 25 line 33
/ / 25/
(Gss] 33
17
\
Y \
RTN
k ...s0 execution will stop here.