Date   : Tue, 12 Apr 1988 15:14:40 EDT
From   : <SAGE@LL.ARPA>
Subject: The Highuser Option in ZCPR33

   The maximum user area displayed by SHOW.COM is not the highest one you
can log into but the highest one you are allowed to reference.  SHOW does
display on one of its screens whether or not the Z33 command processor will
log into high user numbers.  Z33 (and Z34) is the only command processor
that optionally allows user numbers above 15 to be logged into, and there is
considerable risk in doing so.  I implemented that feature as an
intellectual challenge for experimenters who do not mind living on the edge. 
I do not recommend logging into high user areas as a matter of course.
 
   The fact that CD33 will not log into them is a reflection of the sanity
normally built into that program.  It is smart enough to check DU and DIR
references for a valid login range.  It was an oversight that it does not
check the HIGHUSER option bit in the Z33 command processor to see if the
high user numbers are allowed.  I will try to get someone to make the
required change (not at all difficult, since there is a Z33LIB library
routine for checking the HIGHUSER flag bit, I believe).
 
   With Z34 and the extended environment, there is a full drive vector to
replace the overly simplistic maxdrive byte.  CD should be upgraded to
observe the limits imposed by that vector in addition to the maxdrive limit. 
In this way, CD can, like the Z34 command processor, respect holes in the
drive map.