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Chapter 26. M680x0 Dependent Features

 pcrel

Always keep branches PC relative. In the M680x0 architecture all branches are defined as PC 

relative. However, on some processors they are limited to word displacements maximum. When

as

needs a long branch that is not available, it normally emits an absolute jump instead. This

option disables this substitution. When this option is given and no long branches are available,

only word branches will be emitted. An error message will be generated if a word branch cannot

reach its target. This option has no effect on 68020 and other processors that have long branches.

Section 26.6.1 Branch Improvement.

 m68000

as

can assemble code for several different members of the Motorola 680x0 family. The default

depends upon how

as

was configured when it was built; normally, the default is to assemble code

for the 68020 microprocessor. The following options may be used to change the default. These

options control which instructions and addressing modes are permitted. The members of the

680x0 family are very similar. For detailed information about the differences, see the Motorola

manuals.

 m68000

 m68ec000

 m68hc000

 m68hc001

 m68008

 m68302

 m68306

 m68307

 m68322

 m68356

Assemble for the 68000.

 m68008

,

 m68302

, and so on are synonyms for

 m68000

, since

the chips are the same from the point of view of the assembler.

 m68010

Assemble for the 68010.

 m68020

 m68ec020

Assemble for the 68020. This is normally the default.

 m68030

 m68ec030

Assemble for the 68030.

 m68040

 m68ec040

Assemble for the 68040.

 m68060

 m68ec060

Assemble for the 68060.