HP -67 Owner's Handbook Manual page 291

Card Reader Operations
287
Theillustration below should refresh your memory of the addressing
scheme for the storage registers:
Primary Storage Registers
7]
R[]
R[]
Re_
R
RO
Address
25
24
23
22
21
20
Secondary Registers
Address
19
18
17
16
15
14
13
12
11
10
Address
9
8
7
6
5
4
3
2
1
0
To merge data from a magnetic card into selected storage registers:
1. Store in I the number address of the last storage register you
want loaded from the card.
. Press @ (merge) to select the merge mode.
. Pass either side of the magnetic card containing data through
the card reader. If more datais to be loaded, the calculator will
display Crd