Fujitsu F2MC-8FX Manual Do Utilizador
20
CHAPTER 3 REGISTERS
3.3.1
How To Use The Temporary Accumulator (T)
The F
2
MC-8FX CPU has a special-purpose register called a temporary accumulator. This
section described the operation of this register.
■
How to Use the Temporary Accumulator (T)
The F
2
MC-8FX CPU has various binary operation instructions, some data transfer instructions and the
temporary accumulator (T) for 16-bit data operation. Although there is no instruction for direct data
transfer to the temporary accumulator, the value of the original accumulator is transferred to the temporary
accumulator before executing the instruction for data transfer to the accumulator. Therefore, to perform
operations between the accumulator and temporary accumulator, execute operations after carrying out the
instruction for data transfer to the accumulator twice. Since data is not automatically transferred by all
instructions to the temporary accumulator, see the columns of TL and TH in the instruction list for details
of actual data transfer instructions. An example of addition with carry of 16-bit data stored at addresses
1280
H
and 0042
H
is shown below.
Figure 3.3-7 shows the operation for the accumulator and temporary accumulator when the above example
is executed.
Figure 3.3-7 Operation of Accumulator (A) and Temporary Accumulator (T) in Word Data Processing
MOVW A, 0042H -
MOVW A, 12
MOVW A, 12
8
0H -
ADDCW A
-
A
A
A
T
T
T
CF
T
RAM
RAM
RAM
RAM
78
H
78
H
78
H
78
H
56
H
56
H
56
H
56
H
34
H
34
H
34
H
34
H
12
H
12
H
12
H
12
H
XXXX
H
XXXX
H
XXXX
H
1234
H
5678
H
1234
H
68AC
H
1234
H
1281
H
1280
H
0043
H
0042
H
1281
H
1280
H
0043
H
0042
H
1281
H
1280
H
0043
H
0042
H
1281
H
1280
H
0043
H
0042
H
0
...
...
...
...
...
...
...
...
Before execution
Last result
+
A