IDEC MICROSmart FC6A Series, Руководство пользователя

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8: I
NSTRUCTIONS
R
EFERENCE
8-12 FC6A S
ERIES
MICROS
MART
U
SER
’
S
M
ANUAL
FC9Y-B1722
Device Addressing for Instruction Execution
This section provides an explanation about how source and destination devices used by instructions for the execution can be
specified. There are two ways to specify the device to use: Direct Addressing and Indirect Addressing.
Direct Addressing
In direct addressing, source and destination devices are specified with the devices to use.
■
Direct Addressing Operation
■
Devices that can be directly addressed
■
Instructions supporting the direct addressing
All basic and advanced instructions support the direct addressing.
Indirect Addressing
Indirect Addressing Format
The index register Pn indicates the offset from the base device. Indirect addressing is possible by specifying source devices and
destination devices with the base device and the index register. The format of the indirect addressing is as follows:
"Base Device" + ":" + "Pn (Address n of the index register)"
Indirect Addressing Operation
Example: When the source device (D0010) of the MOV(W) is directly specified.
The data in D0010 is transferred to D0002.
I Q M R T C D P Constant
X X X X X X X X X
REP D1 -
D0002
S1 -
D0010
MOV(W)
D0000
D0001
D0002
D0010 Data
Transfer
Example: When the base device is D0010 and the index register P3 is used.
After D0010, add ":" and "P3".
D0010:P3
Example: When the source device (D0010) of the MOV(W) instruction is indirectly specified with P3.
The data in P3 is added to the address of D0010, so D(10 + (P3)) = D (10 + (100)) = D0110, and the data in
D0110 is transferred to D0002.
REP D1 -
D0002
S1 -
D0010:P3
MOV(W)
D0000
P1
D0001
D0002
D0010
+100
10
P0
1
P2
50
P3
100
D0110
Data
Transfer
Index register