The immediate character is $ for Unix compatibility, not # as DEC writes it.
The indirect character is * for Unix compatibility, not @ as DEC writes it.
The displacement sizing character is ` (an accent grave) for Unix compatibility, not ^ as DEC writes it. The letter preceding ` may have either case. G is not understood, but all other letters (b i l s w) are understood.
Register names understood are r0 r1 r2 … r15 ap fp sp pc. Upper and lower case letters are equivalent.
For instance
tstb *w`$4(r5) |
Any expression is permitted in an operand. Operands are comma separated.