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#### 9.33.1 Options

The Zilog Z80 and Ascii R800 version of `as` have a few machine dependent options.

-z80
  Produce code for the Z80 processor. There are additional options to request warnings and error messages for undocumented instructions.
-ignore-undocumented-instructions
-Wnud
  Silently assemble undocumented Z80-instructions that have been adopted as documented R800-instructions.
-ignore-unportable-instructions
-Wnup
  Silently assemble all undocumented Z80-instructions.
-warn-undocumented-instructions
-Wud
  Issue warnings for undocumented Z80-instructions that work on R800, do not assemble other undocumented instructions without warning.
-warn-unportable-instructions
-Wup
  Issue warnings for other undocumented Z80-instructions, do not treat any undocumented instructions as errors.
-forbid-undocumented-instructions
-Fud
  Treat all undocumented z80-instructions as errors.
-forbid-unportable-instructions
-Fup
  Treat undocumented z80-instructions that do not work on R800 as errors.

-r800
  Produce code for the R800 processor. The assembler does not support undocumented instructions for the R800. In line with common practice, `as` uses Z80 instruction names for the R800 processor, as far as they exist.