HP 15c - Manual (Page 108)

108 Section 10: The Index Register and Loop Control
Indirect Addressing
If R
I
contains: % will address:
t V or GV will
transfer to:*
21 R
21
´ b B
22 R
22
" "
C
23 R
23
" "
Á
24 R
24
" "
E
⋮ ⋮ —
65 R
65
—
*For R
I

0 only.
Index Register Arithmetic
Direct. O or l {
+ , -, *, ÷ } V. Storage or recall
arithmetic operates with the Index register in the same manner as upon
other data storage registers (page 43).
Indirect. O or l {
+ , -, *, ÷ } % carries out storage
or recall arithmetic with the contents of the data storage register addressed
by the integer portion of the number (0 to 65) in the Index register. See the
above table.
Exchanging the X-Register
Direct. ´ X V exchanges contents between the X-register and the
Index register. (Works the same as X n does with registers 0 through .9.)
Indirect. ´ X % exchanges contents between the X-register and the
data storage register addressed by the number (0 to 65) in the Index register.
See the above table.
Indirect Branching With
V
The V key—but not the % key—can be used for indirect branching
(tV) and subroutine calls (GV). (Only the integer portion of
the number in R
I
is used.) (% is only used for indirect addressing of
storage registers).