Section 10: The Index Register And Loop Control; The V And % Keys; Direct Versus Indirect Data Storage With The Index Register; The Index Register - HP -15C Owner's Handbook Manual

The Index register (R
HP-15C. In addition to storage and recall of data the Index register can use
an index number to:

Count and control loops.

Indirectly address storage registers, including those beyond R.
(R ).
19

Indirectly branch to program line numbers, as well as to labels.

Indirectly control the display format.

Indirectly control flag operations.

The V and % Keys

Direct Versus Indirect Data Storage With the Index Register

The Index register is a data storage register that can be used directly, with
V, or indirectly, with %.
V
The V function uses the
number itself in the Index
register.
Note that the matrix functions and complex functions use the V and % keys also, but for different
*
purposes. Refer to sections 11 and 12 for their usage.
Section 10

The Index Register

and Loop Control
) is a powerful tool in advanced programming of the
I
*
The difference is important to note:
The % function uses the absolute
value of the integer portion of the
number in the Index register to
address another
register. This is called indirect
addressing.
106
%
data storage
9