Each key pressed in Learn mode will be entered into the current program step, and the program step (Program Counter, or P.C.) will advance to the next step. Pressing PRIME will return to step 0000. The "Set P.C." key may be used to go directly to any program step. Press Set P.C. followed by 4 digits to select a program step. This calculator has 1984 program steps, numbered 0000 through 1983.
Program editing functions (S.M., INS, B.S., DEL) are activated by "Run-Learn" mode, where noth Run and Learn buttons are depressed. This mode functions nearly identically to Learn mode, except for the different functions assigned the PRIME, SET P.C., VERIFY PROG, and RECORD PROG keys.
Also, programs may use the STOP code to cause the program to stop. The user must press GO to continue running the program. This technique is often used to let the user enter variables for the program. It is common to CLEAR X before the STOP, in order to make the request for input obvious. Alternatively, a special, meaningful, value may be in the display (e.g. parameter number being requested).
A program will also stop when it encounters an END PROG code. however, the program cannot be resumed after that (only started over at beginning), as the program counter is reset to 0000.
Also note, having more than one END PROG code in a program can be a problem. Not the least of which is for the List Program mode, but also for recording programs to tape. Normally, if a program has multiple exit points they will all be branches to a single END PROG, and that is at the physical end of all program codes. (See SEARCH/MARK in Programming Techniques). In other words, there should not be any program codes after an END PROG. This also includes any extended register data that might be stored in the program. In addition, the INS and DEL functions for editing programs will depend on a single END PROG code, at the end of all valid code.
Also note that one of the extended registers has same number as the END PROG code (05 12). Accessing this register directly in a program will confuse List Program and the tape functions (and INS/DEL). This also applies to any "two step" program code that might have 05 12 as the second code.
Nothing is known about how debugging was done on the Wang 700 Series. There do not appear to be any trace facilities.