Z80 Directives - Using as
Description: Using as

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#### 9.41.4 Z80 Assembler Directives

`as` for the Z80 supports some additional directives for compatibility with other assemblers.

These are the additional directives in `as` for the Z80:

`db` expression`|`string`[,`expression`|`string`...]`
`defb` expression`|`string`[,`expression`|`string`...]`
  For each string the characters are copied to the object file, for each other expression the value is stored in one byte. A warning is issued in case of an overflow.
`dw` expression`[,`expression`...]`
`defw` expression`[,`expression`...]`
  For each expression the value is stored in two bytes, ignoring overflow.
`d24` expression`[,`expression`...]`
`def24` expression`[,`expression`...]`
  For each expression the value is stored in three bytes, ignoring overflow.
`d32` expression`[,`expression`...]`
`def32` expression`[,`expression`...]`
  For each expression the value is stored in four bytes, ignoring overflow.
`ds` count`[,` value`]`
`defs` count`[,` value`]`
  Fill count bytes in the object file with value, if value is omitted it defaults to zero.
symbol`equ` expression
symbol`defl` expression
  These directives set the value of symbol to expression. If `equ` is used, it is an error if symbol is already defined. Symbols defined with `equ` are not protected from redefinition.
`set`
  This is a normal instruction on Z80, and not an assembler directive.
`psect` name
  A synonym for See Section, no second argument should be given.