HP 0012C-90001 User Manual page 109

We'll key the income into the display before running the program so that it will be
in the X-register when the :0 instruction in program line 01 is executed. This
instruction will place the test value 20,000 in the X-register and (as explained in
Appendix A) move the income into the Y-register. The ~ instruction in program
line 02 will exchange the numbers in the X- and Y-registers (as also explained in
Appendix A): that is, it will place the income back into the X-register and place the
test value into the Y-register. This is necessary because when either the :2
instruction in line 05 or the :1 instruction in line 07 is executed, the number in
the X-register is moved into the Y-register; if the ~ instruction were not included,
the test value 20,000, rather than the income, would be in the Y-register when the
b instruction in line 08 is executed.
Keystrokes Keystrokes Keystrokes Keystrokes
fs
fCLEARÎ
:0
~
go
Section 9: Branching and Loopin Section 9:
Section 9: Section 9:
Display Display Display Display
07- 43, 33 02 Sets calculator to Program mode.
(Display shows program line at
which execution was halted at end
of preceding example.)
00-
Clears program memory.
01- 45 0
Recalls test value into X-register and
places income in Y-register.
02- 34
Places income in X-register and test
value in Y-register.
03- 43 34
Tests whether number in X-register
(income) is less than or equal to
number in Y-register (20,000).
Branching and Looping g g g
Branching and Loopin Branching and Loopin
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