Undefined values: Difference between revisions
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=={{header|Z80 Assembly}}== |
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Nothing is truly "undefined" since any operation will return some 8-bit or 16-bit number. It's more of a question of "does this value mean anything at all." There are actions that will result in "undefined" (read: inconsistent) behavior: |
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* Reading from the <code>R</code> register (returns some value that relates to dynamic memory refresh) |
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* Reading from uninitialized memory (returns whatever happens to be there) |
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* Using <code>IN</code> commands on a port that isn't connected to the CPU, or reading from a write-only port |
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{{omit from|6502 Assembly}} |
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{{omit from|68000 Assembly}} |
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{{omit from|8080 Assembly}} |
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{{omit from|8086 Assembly}} |
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{{omit from|ARM Assembly}} |
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{{omit from|MIPS Assembly}} |
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{{omit from|X86 Assembly}} |
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{{omit from|Z80 Assembly}} |
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{{omit from|GUISS}} |
{{omit from|GUISS}} |
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{{omit from|ACL2}} |
{{omit from|ACL2}} |