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The default type of a M68000 instruction and case sensitivity

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• Recall: Default operand type
  • Recall that:

    The default operand type for integer (= whole number) operations is short ( = .W)

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  • In other words:

    If you do not specify a .B or .W or .L in a integer operation, then: The M68000 assembler (compiler) will assume that you will use short (= .W) as the integer data type !!! In other words: ADD D0, D1 is assumed to be: ADD.W D0, D1 ADD x, D6 is assumed to be: ADD.W x, D6

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• Case sensitivity
  • Fact:

    The M68000 operation code or register name in a M68000 instruction is not case sensitive

    Example:

    add.w d0, d1 is same as: ADD.W D0, D1

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  • Important fact:

    The user defined labels are case sensitive !!!

    Example:

    Correct use of labels: add.l x, D0 ... x: ds.l 1 Incorrect use of labels: add.l X, D0 // X is not the same as x !!! ... x: ds.l 1