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MESC TOOL NEWS:
MESCT-PD79SIM-000416D
PD79SIM and PD77SIM
Precautions
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Please take note of the following problem in using simulator debuggers PD79SIM and PD77SIM:
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Versions Concerned
| PD79SIM V.1.00 Release 1--V.3.00 Release 1 | for the 7900 series MCUs |
| PD77SIM V.1.00 Release 1--V.3.00 Release 1 | for the 77XX series MCUs |
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Problem
When the program that executes the following subtract instructions in the decimal mode is run in PD79SIM or PD77SIM, the accumulator will be loaded with incorrect values:
| - | Instruction |
| 77XX Series MCUs | SBC |
| 7900 Series MCUs | SBC
SBCB |
- 2.1 Conditions
- This problem occurs under either of the following conditions:
- (1)A decimal operation is performed in 16 bits wide using the SBC or SBCB instruction.
- (2)A decimal operation is performed in 8 bits wide using the SBC or SBCB instruction, which results in a borrow of 1.
- 2.2 Examples
- (1)A decimal operation performed in 16 bits wide
- The execution of the following program results in accumulator A being loaded with incorrect value "00B0H"; the correct one is "0050H".
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-----------------------------------------------------------------
CLM
SEP D
LDA A, #0100H
SEC
SBC A, #0050H
-----------------------------------------------------------------
- (2)A decimal operation performed in 8 bits wide with a borrow of 1
- The execution of the following program results in accumulator A being loaded with incorrect value "09H"; the correct one is "91H".
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-----------------------------------------------------------------
SEM
SEP D
LDA A, #01H
SEC
SBC A, #10H
-----------------------------------------------------------------
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Workaround
This problem occurs only in simulator debuggers. Then, if your program contains the descriptions that meet either of the above conditions, please check the result of execution by using an emulator debugger.
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Schedule of Fixing Problem
We plan to fix this problem in our next release.
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