Mitsubishi L02CPU, User Manual, Page: 249 / 340

247
CHAPTER 5 DEVICES
5
5.
2
I
n
te
rnal Us
er Dev
ices
5.
2.
12
Dat
a
re
gi
ster
(D)
5.2.12
Data register (D)
The data register (D) is a memory in which numeric data (-32768 to 32767, or 0000
H
to FFFF
H
) can be stored.
(1) Bit structure of the file register
(a) Bit structure and read/write unit
One point of the data register consists of 16 bits, and data can be read or written in units of 16 bits.
Data register area handled as signed data. In the case of the hexadecimal notation, 0000
H
to FFFF
H
can be stored.
However, because the most significant bit represents a sign bit, decimal values that can be specified are -32768 to 32767.
(b) Using in a 32-bit instruction
For a 32-bit instruction, two consecutive points of the data register (D
n
and D
n+1
) are the target of the
processing. The lower 16 bits correspond to the data register number (Dn) specified in the program, and the
higher 16 bits correspond to the specified data register 1.
When D12 is specified in the DMOV instruction, D12 represents the lower 16 bits and D13 represents the
higher 16 bits.
Data of -2147483648 to 2147483647 or 00000000
H
to FFFFFFFF
H
can be stored in a two-point area of the
data register. (The most significant bit in a 32-bit structure is a sign bit.)
(2) Retention of stored data
The data stored in the data register are held until other different data are stored. Note that the stored data are
initialized when the CPU module is powered off or reset.
Dn
b15
to
b0
The most significant bit is a sign bit.
Ex. Ex.
D13 D12
Upper 16 bits Lower 16 bits
Processing target: D12, D13