HP HP-67 - Page 284

280 Card Reader Operations
4. Select an unclipped magnetic card. Pass side 1 of the card
through the card reader.
a. The contents of the primary storage registers (R, through
Ry, R, through Rg, I) are recorded on side 1. If the calculator’s
protected secondary registers (Rg, through Rgg) all contain
zero data, those contents are ‘‘compressed’’ and recorded on
side 1 also. The calculator displays the original contents of the
X-register to indicate that all data has been correctly recorded.
b. If any of the secondary storage registers (Rgo through Rgg)
contain nonzero data, the display shows to
indicate that a second side is necessary to record all the data.
c. Pass side 2 of the card through the card reader. The actual
contents of the secondary storage registers Rg, through Rg
are recorded on the second side of the card.
5. All data has now been recorded on the magnetic card. In
addition, the data remains intact in the calculator.
Besides the data from the storage registers, the HP-67 also records
the following information onto a data card on either or both passes
through the card reader:
1. The fact that data (not a program) is being recorded.
2. The fact that this is side 1 (or side 2).
3. Whether or not two passes are required.
4. A checksum (a code to verify that the data is complete when it
is reloaded).
No calculator status information is recorded when data is recorded
onto a magnetic card.
When data is recorded on a side of a magnetic card, it wipes out
whatever information was previously on that side. To record data
permanently on a card, so that it can never be lost, you can clip a
corner of the recorded magnetic card, just as you do to permanently
save a recorded program.