DOUMENTATION FOR SPEC.COM

CP/M command specification:    SPEC filename.COM

where <filename> represents the filename and filetype of a valid
CP/M file containing object code which is loaded at 100h.

The program will abort with an appropriate message if

(1)  No filename is specified, or
(2)  The file does not exist on the default drive.

It is recommended that both SPEC and the target file be on the
default drive.

Also, note that SPEC is limited to files not greater than two
extents. This was both for necessity and to avoid 16-bit arithmetic,
however, if anyone would like to modify the program to include
larger files, I might be willing to provide the source to them.
Leave me a message on the boards...



The program provides two degrees of protection:

(1)  A reference byte is stored on the system track the first time
     the protected file is loaded.  For this reason, the protected
     program must exist on a standard disk format in which the outer
     track (TRK00) is reserved for the operating system.  If the
     disk is copied, without copying the same system tracks, the
     program will terminate with 'UNLAWFUL COPY' and a warm boot.

     This byte is stored in the CP/M proprietary message and should
     not effect the operating system.

(2)  A counter byte is stored and referenced in memory and compared
     against SPEC.  SPEC is requested when the program is first
     called and represents the number of loads you designate for the
     protected file.  When SPEC has been reached, the protected
     program will then self-erase.  Any attempts to unerase will be
     useless since the program will also write over itself.

The purpose of this program was to provide software on a trial basis
for my clients.  If they decided against purchasing, the software
would self-destruct and they would be unable to use it further.  I
thought this was a good idea at the time, and I still think it is a
good idea.  However, it is very difficult to protect CP/M programs
since there does not appear to be any way to absolutely reference
the disk.  SPEC uses direct BIOS calls, against all the edicts of
Digital Research, and they proved, if you'll forgive my French, to
be a royal pain in the butt.  It was necessary to set up alternate
stacks and DMA's within the protected program and even then some
CP/M utilities, like STAT, seem to behave erratically after run
against SPEC.  Ordinary programs, however, seem to run okay and so I
am releasing SPEC to the domain albeit retaining exclusive
copyrights.

It's back to my experiments with the 1793 to see if there is any way
to mark the disk.  If any of you have any insight into referencing
the gap or ID, I would sure like to hear about it!!!!

J. Fremont
Los Angeles
August 13, 1985