Syntax
------

   The 680x0 version of `as' uses syntax similar to the Sun assembler.
Size modifiers are appended directly to the end of the opcode without an
intervening period.  For example, write `movl' rather than `move.l'.

   In the following table "apc" stands for any of the address registers
(`a0' through `a7'), nothing, (`'), the Program Counter (`pc'), or the
zero-address relative to the program counter (`zpc').

   The following addressing modes are understood:
"Immediate"
     `#DIGITS'

"Data Register"
     `d0' through `d7'

"Address Register"
     `a0' through `a7'

"Address Register Indirect"
     `a0@' through `a7@'

"Address Register Postincrement"
     `a0@+' through `a7@+'

"Address Register Predecrement"
     `a0@-' through `a7@-'

"Indirect Plus Offset"
     `APC@(DIGITS)'

"Index"
     `APC@(DIGITS,REGISTER:SIZE:SCALE)'

     or `APC@(REGISTER:SIZE:SCALE)'

"Postindex"
     `APC@(DIGITS)@(DIGITS,REGISTER:SIZE:SCALE)'

     or `APC@(DIGITS)@(REGISTER:SIZE:SCALE)'

"Preindex"
     `APC@(DIGITS,REGISTER:SIZE:SCALE)@(DIGITS)'

     or `APC@(REGISTER:SIZE:SCALE)@(DIGITS)'

"Memory Indirect"
     `APC@(DIGITS)@(DIGITS)'

"Absolute"
     `SYMBOL', or `DIGITS'