Appendix D

Common Errors

1. Having unwanted duplicate names (labels) for user defined functions in memory because fPRGM wast not pressed in W/PRGM mode before keying in a program.
2. Inadvertently erasing a program in memory by inserting a magnetic card when W/PRGMRUN switch is set to RUN.
3. Inadvertently erasing a program on a magnetic card by inserting an unprotected magnetic card when W/PRGMRUN switch is set to W/PRGM.
4. Keying unwanted operations into program memory because the W/PRGMRUN switch is set to W/PRGM when keys are pressed.
5. Failing to shift up to a gold function (f or f-1) or down to a blue function (g) because prefix key was omitted.
6. Losing the T-register contents because the entry of a new number or the recall of a register lifts the stack.
7. Destroying the contents of register R9 because a trigonometric function, a relational test, or the rectangular-polar conversion was done.
8. Failing to take account of a merged code and to provide a NOP as filler in a two-step skip.
9. Performing a trigonometric function in the wrong angular mode.
10. Mistakenly trying to call user defined functions labelled 0, . . . , 9. Only A, . . . , E can be used to label or call deleted functions.
11. Forgetting to clear flags before using them.
12. Expecting gLSTX, stack, or registers to remain unchanged after calling a user defined function from the keyboard (letters A, . . . , E) or within a program.