Texas Instruments TI Programmable 57 User Manual

(2nd) il — THE “DECREMENT
AND SKIP ON ZERO" SEQUENCE
| Osz | = THe “DECREMENT AND Sup on ZERO” Key SEQUENCE
This key sequence is a powerful one. It lets you set up a repetitive
calculation (or “loop'’) for as many times as you select. (You store the
number of repetitions in memory zero). What this sequence really does is
allow you to control whether or not the program pointer moves on to the
step that immediately follows it, or skips that step and goes on to the next
one. When the program pointer comes to a GM key sequence ina
program here’s what happens:
+ First, the contents of memory zero are decreased by one. (This
assumes that a positive integer is in memory 0. Ii a fractional
number is in memory zero, the calculator ‘acts’ as if the next
larger number is in memory zero. If a negative number is in
memory zero, it is incremented by one.)
The calculator then asks: is the content of memory zero equal to
zero?
- Ifthe answer is no, the program pointer proceeds right on to the
step following Lis:
If the answer is yes, the program pointer skips the following
instruction and continues.
.
The step that immediately follows the MM key sequence can be
anything, but a n instruction is often handy at this point for setting up
repetitive calculations. For example, in the program situation shown in
the diagram, the “series of program instructions’ would be executed
repetitively because of the loop.
The number of times the
‘instructions’ were executed would
“Series of b
Progrd-a fasinactions" e controlled by the number stored
in memory zero (stored before
running the program). If a 6 were
stored in memory zero, the series of
instructions would be carried out 6
times, then the program would halt,
Note that the series of instructions would also be executed 6 times if a 5.2,
a —6,ora —5.2 were stored in memory zero before the program pointer
arrived at this series of instructions. Also, be aware of the fact that since
memory zero is involved whenever [sé] HMM is used, it cannot be used for
other storage purposes while handling a [nd] BM sequence, although the
number in memory 0 can be used as part of the computational sequence
by recalling it.

Texas Instruments TI Programmable 57 Specifications

General

Brand	Texas Instruments
Model	TI Programmable 57
Category	Calculator
Language	English