This document explains zkpch.dat and the background fast-initialization
process.

A C++ interpreter has to do a lot of initialization of internal tables,
etc., before it can start working.  But an interpreter should start
immediately when you invoke it from the operating system command line.
To make zk start immediately, the initialization is done by the
background process, which keeps the initialization data handy, such
that zk can access it via shared memory.  The data comes from zkpch.dat.

When you use header files for your c++ code, you can input them any
time by using #include, but for maximum convenience it's usually
better to have the header files you use most often precompiled into
zkpch.dat.  You need the pro version of zk to precompile header files.
The first step is to edit newpch.ini to add your header files to it,
then run newpch.bat by typing "newpch" at the operating system command
line.

Also, if you build a new version of zk.exe (see link.txt for details)
you have to build a new version of zkpch.dat, using newpch.bat as
mentioned above, because the old version of zkpch.dat will not be
compatible with your new version of zk.exe, and will probably cause
various messy bug symptoms if you try to use the old version of one with
the new version of the other.  Be sure you archive and delete or rename
the old version of zk.exe before you run newpch.bat in this situation,
to be sure it isn't somehow using the old version instead of the new.

The background fast-initialization process stays up till you log out.
If it gets in your way for any reason, you can get rid of it by using
killzkmd.bat, which you invoke by typing "killzkmd" at the NT command
line.  Then, to start it again, just run zk again, which will start it
when it notices that it's gone.  You can inquire whether the background
process is up by using zkmdup.bat, which you invoke by typing "zkmdup"
at the operating system command line, and it will give you a simple
"up" or "down" answer.

Normally there won't ever be a reason to use killzkmd, because the
background process will normally not get in your way, and in fact you
probably won't even notice it, except when you see zk start it.  It
does use space in your pagefile, and if that turns out to be a problem,
you should increase the size of your pagefile, and/or set zkmb=9
or some other number.  Whether you should increase or decrease zkmb,
or not set it at all, depends on the situation.  Normally you should
not set zkmb at all, and if you run out of memory, you should normally
just increase the size of your pagefile, by going to the program
manager --> control panel --> system --> virtual memory.  But if you
do set zkmb, you have to use killzkmd.bat (mentioned above) to make
the new number take effect.

Also, if you don't have much RAM, you should add more.  NT is a very
RAM intensive operating system, and the amounts recommended are not
really enough for the best performance.  Zk should always feel
responsive and should not take more than a fraction of a second to
start.  If it does, shortage of RAM is the most likely cause.  But
don't confuse RAM with virtual memory.  Virtual memory is determined
by the size of your pagefile, and is what can cause error messages
by not having enough.  RAM causes sluggishness when you don't have
enough, but doesn't normally cause error messages.