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Using the Inverse Assembler

This section discusses the general output format of the inverse assembler,

and any processor-specific information you will need.

The MC68306 microprocessor does not indicate externally which word

fetched is the beginning of a new instruction. You may have to "point" to the

first state of an instruction fetch to synchronize the inverse assembler. Once

synchronized, the inverse assembler will disassemble from this state through

the end of the screen. See "To synchronize the inverse assembler" later in

this chapter for more information.

General Output Format

The next few paragraphs describe the general output format of the inverse

assembler.

Numeric Format

Unless a value is followed by a suffix character, numeric output from the

inverse assembler is in hexadecimal format. For example, decimal values

have a period (.) as the suffix character; binary values have a percent sign

(%).

Missing Opcodes

Asterisks (*) in the inverse assembler output indicate that a portion (or

portions) of an instruction was not captured by the analyzer. Missing

opcodes occur frequently and are primarily due to microprocessor prefetch

activity. Storage qualification, or the use of storage windows, can also lead to

such occurrences.

Don’t Care Bytes

The MC68306 microprocessor can perform byte, word, and long word

transfers. During operand reads and writes, entire 16-bit (word) values

appear on the microprocessor data bus. lines. The inverse assembler displays

"xx" for any bytes in a transfer that are ignored by the microprocessor. You

can determine exactly which byte or bytes of data were used as an operand.

2–10 MC68306 Preprocessor

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Motorola MC68306 Betriebsanweisung Seite 47