Nope!
I use the start/stop at a logic choice. For example the great circle heading program requires a test for a ve value which determines the east or south direction (360 +). When the program pauses it displays a +ve or ve value for the sine of the heading. If negative pressing start/stop calculates the reciprocal value of the heading and displays that.
You will notice prgm 1&2 switch. Each program is 49 lines and switching to the other allows a program to continue.
Interestingly, if you input the values in the stack at the correct points while programming the display shows your progress!
Cheers
here are two programs, one resides at position 1 and the other at 2 using the switch. You can see that if the sine is negative then the last routine in program two will switch the heading for you. See the explanation in program two contained by the ***
PROGRAM LISTING Great circle distance
RCL 3

RCL 1
= A
SIN/COS
2ND
STO 4
RCL 0
SIN/COS
2ND B
STO * 4
RCL 2
SIN/COS
2ND C
STO * 4
RCL 0
SIN/COS
* D
RCL 2
SIN/COS
=
+
RCL 4
=
SIN1/COS1 E
2ND
STO 5
*
60 F
=
STOP
PROGRAM SECTION EXPLANATION
A = COS(LON.I – LON.F)
B = COS(LAT.I)
C = COS(LAT.F)
D = SIN(LAT.I) * SIN(LAT.F) +
A * B * C
E = ARCOS(D)
F = DISTANCE NM
USE IN PLACE OF 60
69 FOR SM
111.11 FOR KM
VARIABLE REGISTERS
LAT.I 0
LON.I 1
LAT.F 2
LON.F 3
A 4
A * B 4
A * B * C 4
DISTANCE ARC 5
____________________________________________________
____________________________________________________
PROGRAM LISTING GREAT CIRCLE BEARING
RCL 0
SIN/COS
2ND
* A
RCL 5
SIN/COS
=
STO 6
RCL 0
SIN/COS
*
RCL 5 B
SIN/COS
2ND
=
STO 7
RCL 2
SIN/COS C

RCL 7
/
RCL 6
=
SIN1/COS1 D
2ND
STO 8
STOP
RCL 1

RCL 3
= E
SIN
STOP
360
 F
RCL 8
=
STOP
PROGRAM SECTION EXPLANATION
A = cos(LAT.I) * sin(DIST ARC)
B = sin(LAT.I) * cos(DIST ARC)
C = sin(LAT.F)  (sin(LAT.I) * cos(DIST ARC)
D = COURSE *** the course
E = TEST FOR NEGATIVE SIGN will be a +VE
F = IF SIGN NEGATIVE EXECUTE F FOR number but is it
CORRECT BEARING. correct? Pressing
st/st displays the
VARIABLE REGISTERS sine and its
LAT.I 0 value allowing the
LON.I 1 user to make the
LAT.F 2 correct choice***
LON.F 3
DISTANCE ARC 5
BEARING FOR SIGN TEST 8
Edited: 29 Nov 2010, 10:12 p.m.