CY7C67200
Registers
Some registers have different functions for a read vs. a write access or USB host vs. USB device mode. Therefore, registers of this type have multiple definitions for the same address.
The default register values listed in this data sheet may be altered to some other value during BIOS initialization. Refer to the BIOS documentation for Register initialization information.
Processor Control Registers
There are eight registers dedicated to general processor control. Each of these registers is covered in this section and is summarized in Table 16.
CPU Flags Register [0xC000] [R]
Table 16.Processor Control Registers
Register Name | Address | R/W |
CPU Flags Register | 0xC000 | R |
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Register Bank Register | 0xC002 | R/W |
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Hardware Revision Register | 0xC004 | R |
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CPU Speed Register | 0xC008 | R/W |
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Power Control Register | 0xC00A | R/W |
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Interrupt Enable Register | 0xC00E | R/W |
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Breakpoint Register | 0xC014 | R/W |
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USB Diagnostic Register | 0xC03C | W |
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Figure 7. CPU Flags Register
Bit # | 15 | 14 | 13 | 12 |
| 11 | 10 | 9 | 8 |
Field |
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| Reserved... |
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Read/Write | - | - | - | - |
| - | - | - | - |
Default | 0 | 0 | 0 | 0 |
| 0 | 0 | 0 | 0 |
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Bit # | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
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| ...Reserved |
| Global | Negative | Overflow | Carry | Zero |
Field |
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| Interrupt | Flag | Flag | Flag | Flag |
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| Enable |
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Read/Write | - | - | - | R | R | R | R | R |
Default | 0 | 0 | 0 | X | X | X | X | X |
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Register Description
The CPU Flags register is a read only register that gives processor flags status.
Global Interrupt Enable (Bit 4)
The Global Interrupt Enable bit indicates if the Global Inter- rupts are enabled.
1:Enabled
0:Disabled
Negative Flag (Bit 3)
The Negative Flag bit indicates if an arithmetic operation results in a negative answer.
1:MS result bit is ‘1’
0:MS result bit is not ‘1’
Overflow Flag (Bit 2)
The Overflow Flag bit indicates if an overflow condition has occurred. An overflow condition can occur if an arithmetic
result was either larger than the destination operand size (for addition) or smaller than the destination operand should allow for subtraction.
1:Overflow occurred
0:Overflow did not occur
Carry Flag (Bit 1)
The Carry Flag bit indicates if an arithmetic operation resulted in a carry for addition, or borrow for subtraction.
1:Carry/Borrow occurred
0:Carry/Borrow did not occur
Zero Flag (Bit 0)
The Zero Flag bit indicates if an instruction execution resulted in a ‘0’.
1:Zero occurred
0:Zero did not occur
Document #: | Page 10 of 78 |
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