MAKECRC
                   32-Bit CRC Utility for ZZAP


As an added line of defense in the war against viruses ZZAP
canautomatically compute the CRC's of the programs it executes
and compare them to a value specified in the configuration file.
CRC short for Cyclical Redundancy Check.  A normal checksum of
files is not very secure because it's simple to modify a file
without changing the checksum.  When using a CRC, however, it's
almost impossible to modify a file and keep the original CRC
value.  The order of the byte values, not just the values are
major factors when computing a CRC.  ZZAP uses a 32-bit checksum,
resulting in over 4 billion (2^32) possible values.

When ZZAP is run with CRC validation enabled the time required to
compute the checksum will not be noticable on a medium to fast
computer.  On slow XT class systems you should run a few tests to
decide if the extra time is tolerable.  A fast hard-disk or a
good disk cache can make the world of difference.

MAKECRC.EXE is used to create a datafile containing the CRC
information for ZZAP to use.  Using any standard text editor,
create a file named FILES.CRC.  For each program you wish
validated, place its filename (with extension) in the file, one
filename per line.  If the program file is not on the
enviroment's PATH you must also include the full path.  After
creating this file simply execute MAKECRC in the same directory
as FILES.CRC.  It will create the file ZZAP.CRC which should be
placed in the same directory as ZZAP.CFG.

If any of the programs you listed in FILES.CRC updated you should
re-execute MAKECRC so that ZZAP.CRC is updated as well.  If you
fail to do this ZZAP the CRC's in ZZAP.CRC will probably not be
correct and ZZAP will refuse to execute the program.

To enable the automatic CRC testing of program files include the
/Y switch on the command line or include it in the SWITCH=
configuration file directive.

To improve performance ZZAP will only compute the CRC of a
program that is about to be executed.  Once the CRC is computed
for a particular program it will not be recomputed during that
run of ZZAP.  Programs that aren't executed by ZZAP will not have
their CRC's verified.