¡ Semiconductor |
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| MSM80C154S/83C154S | |||||||
Program status word register (PSW) |
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| NAME | ADDRESS | MSB |
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| LSB | |
| 7 |
| 6 | 5 | 4 |
| 3 |
| 2 |
| 1 | 0 |
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| PSW | 0D0H | CY |
| AC | F0 | RS1 |
| RS0 |
| OV |
| F1 | P | |
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| BIT LOCATION | FLAG |
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| FUNCTION |
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| PSW.0 | P | Accumulator (ACC) parity indicator. |
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| This bit is "1" when the "1" bit number in the accumulator is an odd number, and | ||||||||||||
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| "0" when an even number. |
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| PSW.1 | F1 | User flag which may be set to "0" or "1" as desired by the user. |
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| PSW.2 | OV | Overflow flag which is set if the carry C6 from bit 6 of the ALU or CY is "1" as a | ||||||||||||
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| result of an arithmetic operation. The flag is also set to "1" if the resultant product | ||||||||||||
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| of executing multiplication instruction (MUL AB) is greater than 0FFH, but is reset | ||||||||||||
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| to "0" if the product is less than or equal to 0FFH. |
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| PSW.3 | RS0 | RAM register bank switch |
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| RS1 |
| RS0 | BANK |
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| RAM ADDRESS |
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| 0 |
| 0 | 0 | 00H - 07H |
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| PSW.4 | RS1 | 0 |
| 1 | 1 | 08H - 0FH |
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| 1 |
| 0 | 2 | 10H - 17H |
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| 1 |
| 1 | 3 | 18H - 1FH |
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| PSW.5 | F0 | User flag which may be set to "0" or "1" as desired by the user. |
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| PSW.6 | AC | Auxiliary carry flag. |
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| This flag is set to "1" if a carry C3 is generated from bit 3 of the ALU as a result of | ||||||||||||
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| executing an arithmetic operation instruction. |
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| In all other cases, the flag is reset to "0". |
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| PSW.7 | CY | Main carry flag. |
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| This flag is set to "1" if a carry C7 is generated from bit 7 of the ALU as result of | ||||||||||||
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| executing an arithmetic operation instruction. |
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| If a carry C7 is not generated, the flag is reset to "0". |
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