HP 15c - Manual (Page 107)

Section 10: The Index Register and Loop Control 107
Indirect Program Control With the Index Register
The V key is used for all forms of indirect program control other than
indirect register addressing. Hence, V (not %) is used for indirect
program branching, indirect display format control, and indirect flag
control.
Program Loop Control
Program loop counting and control can be carried out in the HP-15C by any
storage register: R
0
through R
9
, R
.0
through R
.9
, or the Index register (V).
Loop control can also be carried out indirectly with %.
The Mechanics
Both V and % can be used in abbreviated key sequences, omitting the
preceding ´ prefix (as explained on page 78).
Index Register Storage and Recall
Direct. O V and l V. Storage and recall between the X-
register and the Index register operate in the same manner as with other data
storage registers (page 42).
Indirect. O (or l) % stores into (or recalls from) the data storage
register whose number is addressed by the integer portion of the value (0 to
65) in the Index register. See the table below and on the next page.
Indirect Addressing
If R
I
contains: % will address:
t V or G V will
transfer to:*
± 0 R
0
´ b 0
⋮ ⋮ ⋮
9 R
9
´ b 9
10 R
.0
" " .0
11 R
.1
" " .1
⋮ ⋮ ⋮
19 R
.9
´ b .9
20 R
20
" " A
*For R
I

0 only.
(Continued on next page.)