Date   : Thu, 05 Apr 1984 06:55:51-MST
From   : Rick Conn <RCONN@SIMTEL20.ARPA>
Subject: Re: ZCPR3

David,

I am writing a book on ZCPR3, and this will address your questions
in much greater detail.  In a nutshell, ZCPR1/ZCPR2/ZCPR3 do not address
programs which use overlays.  Such would require a BDOS modification.
There is a way around this problem, however, with ZCPR3.  As I mentioned,
one feature of ZCPR3 is the alias.

The alias allows the user to define a sophisticated command line which
is executed in place of a simple command issued by the user.  I am running
WS and dBASE II, as well as BDS C, C/80, and PASCAL/MT+ under ZCPR3,
and, by using a combination of aliases and ZEX command files, all are
fitting into the ZCPR3 environment.

Each commercial program must be addressed independently,
since they all handle things differently.  WS, for instance, will, when
not finding its overlays in the current directory, drop down to disk A,
current user and look there.  Hence, I use WS only from a directory called
TEXT, where TEXT is B7: and WS.COM and its overlays, including a spelling
checker, are in A7:.  The search path is A$ A15 (including current dir
by default), so issuing WS from B7 will find WS.COM in A7 (the A$
part of the path expands into A7 when the command is issued from d7).

When it comes to program editing, I use WM, which requires not overlays
and optionally can use a HLP file (which will be found in A$ if not found
in the current dir).  WM is in the root (A15), so it is found from anywhere on
the system.

dBASE II was quite different in that it had to have its overlays in
the current directory.  To get around this problem, I created an alias
which, in response to the command DB2, will issue the following
command sequence:

               A9:;dbase setup;$d$u:

where:

               A9: -- logs me into the directory containing DBASE.COM
                       and its overlays
               dbase setup -- runs DBASE.COM, and SETUP.CMD contains
                       the command "set default to B:", which places
                       me into B9: to do the work; when I issue the
                       "quit" command, the last command is executed:
               $d$u: -- returns me to the directory I was in originally

Finally, with the three languages I mentioned above, all support the ability
to indicate where the required overlays are located.  ZEX command files are
used to do the compilation, linking, and cleanup.  Also, for each language,
the files supporting the compilers and linkers are in An: while the work areas
are in Bn:, such as A2: containing BDS C compiler and linker while B2:
contains the files I am working on.

You will see more on this when the book comes out.

       Rick