by Richard Russell, March 2011
One thing that distinguishes the pseudo-variables (HIMEM, LOMEM, PAGE, PTR# and TIME/TIME$) from regular variables is that writing or reading a pseudo-variable may have a side effect in addition to what you would expect it to do. So for example a statement like:
LOMEM = LOMEM
which you might not expect to do anything, actually does have an effect which could be important.
The main side effects from accessing the pseudo-variables are listed below: