HP HP-67 - Page 298

294 Card Reader Operations
5. Ifthe calculator display shows Crd , insert the second
side of the magnetic card into the card reader.
6. Execution will resume automatically when the card is read.
The automatic card read during (PAUSE] allows the programmer to
even be absent when the card is read! If no card is read, naturally,
the program continues execution after the 1-second pause. If a com-
plete card is not accurately read, the program stops and the calculator
displays to indicate that the read was not successful.
If you wish, instead of utilizing an automatic read during a(PAUSE],
you can simply hold the magnetic card poised in your hand and
insert it during a (PAUSE]
The data entry flag, flag F3, is set either by digit entry from the
keyboard or by the loading of data from a magnetic card. Thus you
could also set up a loop using and the data entry flag F3
that would hold up the program until you pass a data card through
the card reader, then resume execution automatically.
If you wish a program to stop execution to record data on a card,
simply insert the instruction in the program at the point
where you wish to record data. The program will stop at that point
and display to prompt you to pass a card through the
card reader slot. After you start a program running, you can even have
a card ‘‘waiting’’ in the card reader for an automatic recording of data
onto the card.
Example: The example shown here illustrates how you can pause
to read a program from a magnetic card and how a program from a
card may be merged into a program already loaded into the calculator.
The program that you record onto the magnetic card calculates the
area of a circle from its radius. The program that you then load into
the calculator performs 100 iterations, then merges the program from
the card that you have waiting in the card reader into the calculator,
and finally calculates the area of a circle.