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68
Section 6: Memory and Storage
When the calculator converts between Integer and Floating-Point
Decimal modes, the register contents are not changed. However,
due to differences in the internal representation of the two modes,
contents stored in Integer mode will not have the same value in
Floating Point mode, and vice-versa. The integrity of the contents
is preserved, however, when the calculator converts back to the
original mode and word size.
Clearing Data Storage Registers
Pressing
CLEAR
(clear registers) clears the contents of all
data storage registers to zero. (It does not affect the stack or the
LAST X register.) To clear a single data storage register, store zero
in that register. Resetting Continuous Memory clears all storage
registers and the stack.
The Index Register
The Index register (R)) is a permanent storage register that can be
used to indirectly address other storage registers, indirectly branch
to program labels, and hold loop counters for program loop control.
(The latter two uses are discussed in section 9.) Unlike other
storage registers, the Index register is always 68 bits, regardless of
current word size, and it is never converted to lines of program
memory.
Abbreviated Key Sequences
Whenever the
or
key is used following another function key
(such as [STO], [RCL], [GTO], or [GSB]), the
prefix key before the [I]
or [(i)] can be omitted since the sequence is unambiguous. This is
called an abbreviated key sequence. For example, [STO](1]is shorter
than [STO](f](1] but has the same effect.
Storing and Recalling Numbers in the Index Register
The contents of the Index register itself are accessed using the
function:
(1],
(1], or [xx1]. A number stored in R} will be
represented in a 68-bit format, numerically equivalent to the
number in the X-register. A number copied from Rinto X will be
truncated to fit the word size, preserving the least significant bits.*
*If the contents of Ry are recalled in a word size smaller than that used to store the
contents, the recalled value may not be numerically equivalent to the value in Ry.
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