HP 82104A Owner's Handbook Manual page 32

30 Card Reader Operations
Using the ([ver](verify) function, you can determine the card type and the
track number, or, the fact that the card is bad or is unrecognizable.
The calculator and card reader do this verification by using the informa-
tion on the card to compute a ''checksum.'' This checksum is written
with the information on the card when the card is first written. The
function reads the card and recomputes this checksum. It then compares
this checksum to the checksum that was originally written on the card.
If the checksumsare the same, the track is good; if the checksums are not
the same, the track is bad. is not programmable (cannot be keyed
in as an instruction in a program).
The procedure for using is:
1. Execute [ver]. The HP-41C will prompt you for the card with
CARD
2. Insert any of the cards you wish to verify, one track at a time,
into the card reader. If the card is blank or is not a proper HP-41C
or HP-67/HP-97 type card, the calculator will display this mes-
sage:
CARD ERR
If the card is bad, that is, the checksums were not equal, the
display will show
CHECKSUM ERR
Good cards will be analyzed by the system to determine their type
and track number. The calculator will show the following display:
TYPE t TR nn
where 1 is one of the following card types:
P Program Card
D Data Card
) Status Card
A ""Write-All'" Card
7P HP-67/HP-97 Program Card
7D HP-67/HP-97 Data Card