112 Section 10: Program EditingTo add instructions within a program, you could simply key in the newinstructions, beginning at the proper program line, followed by the originalinstructions from that program line through the end of the program. This methodis described below under Adding Instructions by Replacement. Wheninstructions must be added in the middle of a long program, however, using thismethod will require you to key in numerous instructions – namely, the originalinstructions from the point at which the new instructions are added through theend of program memory. Since keying in these instructions may require asignificant amount of time, in such situations you may prefer to use the methoddescribed below under Adding Instructions by Branching.That method basically involves branching to the new instructions which arestored at the end of program memory, then branching back to the program lineimmediately following the line from which you branched out. Adding instruc-tions by branching is not so simple as adding instructions by replacement; how-ever, it generally will require fewer keystrokes whenever there are more thanfour program lines between (and including) the first line to be executed after thenew instruction(s) and the last line you keyed into program memory. Further-more, if program memory includes branches to program lines following the pointat which the new instruction(s) are being added, adding instructions by branch-ing will not require that you change the line numbers specified in the iinstructions, which may be necessary when you add instructions by replacement.Adding Instructions by Replacement1. Press fs to set the calculator to Program mode.2. Press gi. followed by three digits that specify the last program lineto be executed before the added instruction(s). This sets the calculator tothe proper program line for adding the new instruction(s) in the next step.3. Key in the new instruction or instructions.4. Key in the original instruction or instructions, beginning with the firstinstruction to be executed after the added instruction(s), and continuingthrough the last instruction you keyed into program memory.Note: If program memory includes branches to program lines followingthat at which the first new instruction is being added, remember to changethe line number(s) specified in the i instruction(s) – as described aboveunder Changing the Instruction in a Program Line – to the actual new linenumber(s).Example: Assuming you have added a - instruction at the end of programmemory as in the preceding example, suppose you now wanted to insert an tinstruction before the - instruction so that the program will display the amountof the tax before displaying the net income after tax. Since there is only one
