! is the line comment character.
You can use ; instead of a newline to separate statements.
Since $ has no special meaning, you may use it in symbol names.
You can use the predefined symbols r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14, and r15 to refer to the SH registers.
The SH also has these control registers:
procedure register (holds return address)
program counter
high and low multiply accumulator registers
status register
global base register
vector base register (for interrupt vectors)
as understands the following addressing modes for the SH. Rn in the following refers to any of the numbered registers, but not the control registers.
Register direct
Register indirect
Register indirect with pre-decrement
Register indirect with post-increment
Register indirect with displacement
Register indexed
GBR offset
GBR indexed
PC relative address (for branch or for addressing memory). The as implementation allows you to use the simpler form addr anywhere a PC relative address is called for; the alternate form is supported for compatibility with other assemblers.
Immediate data