HP 35s HP 35s scientific calculator - User Guide - Page 216

To To a specific line number: label line number (line number < 1000). For example, A. For example, press A . The display will show If you want to go to the first line of a label, for example. A001: (press and hold), the display will show Conditional Instructions Another way to alter the sequence of program execution is by a conditional test, a true/false test that compares two numbers and skips the next program instruction if the proposition is false. For instance, if a conditional instruction on line A005 is that is, is x equal to zero?), then the program compares the contents of the X-register with zero. If the X- register does contain zero, then the program goes on to the next line. If the X- register does not contain zero, then the program skips the next line, thereby branching to line A007. This rule is commonly known as "Do if true." Do next if true. . . . 2 1  2 . . . 1 . . . Skip next if false. The above example points out a common technique used with conditional tests: the line immediately after the test (which is only executed in the "true" case) is a branch to another label. So the net effect of the test is to branch to a different routine under certain circumstances. There are three categories of conditional instructions: 14-6 Programming Techniques