Category:Z80 Assembly: Difference between revisions
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==Flags== |
==Flags== |
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The flags, or condition codes, are set or cleared as appropriate by various actions. |
The flags, or condition codes, are set or cleared as appropriate by various actions. This is just an overview of the flags - you'll need to check a hardware manual for a full list of which commands affect the flags and in what ways. |
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* Zero flag = equals 1 when the last math operation resulted in a 0, and equals 0 if not. Note that loading a zero (or any value really) into a register does NOT affect this flag, which is not the case for every CPU out there. |
* Zero flag = equals 1 when the last math operation resulted in a 0, and equals 0 if not. Note that loading a zero (or any value really) into a register does NOT affect this flag, which is not the case for every CPU out there. |
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* Sign Flag = equals 1 if the last instruction resulted in a negative number (i.e. bit 7 of the byte is set, or bit 15 if 16-bit registers were used.) The Game Boy doesn't have this flag, but you can make up for that by using the BIT instruction to test bit 7 yourself. |
* Sign Flag = equals 1 if the last instruction resulted in a negative number (i.e. bit 7 of the byte is set, or bit 15 if 16-bit registers were used.) The Game Boy doesn't have this flag, but you can make up for that by using the BIT instruction to test bit 7 yourself. |
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This is just an overview of the flags. You'll need to check a hardware manual for a full list of which commands affect the flags and in what ways. |
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==Assembler Syntax== |
==Assembler Syntax== |
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