SCRXY
                                   =====

Get screen dimensions directly from screen driver - without use of
a channel!

        SCRXY limX%, limY%

Where limX% / limY% are return parameters only

Parameter errors trigger the standard error reponse.


Note:
-----

If the Pointer Interface (PI) is not present the "standard" values, ie
512 and 256, are returned instead. Clearly, this wont be correct if you
have a 768x512 screen size and no PI! This, however, appears to be how
TK2's SDUMP does things, so Im happy with that.


Software status:
----------------

V0.01, pjw, 26 Oct 2018
V0.02, pjw, June 5th 2019, check parameters, now Qdos + PI compatible
V0.03, pjw, 2021 Oct 03, if no PI return "standard" sizes

Conditions and DISCLAIMER as per Knoware.no