Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!ames!think!bloom-beacon!mit-eddie!bbn!humming!simcha
From: simcha@humming.UUCP (Simcha Lerner)
Newsgroups: comp.sys.ibm.pc
Subject: Re: archive bit
Keywords: say what?
Message-ID: <233@humming.UUCP>
Date: 21 Jul 88 22:23:49 GMT
References: <4873@killer.DALLAS.TX.US>
Reply-To: simcha@humming.UUCP (Simcha Lerner)
Distribution: na
Organization: Kurzweil A.I. Waltham, Mass.
Lines: 36

In article <4873@killer.DALLAS.TX.US> bobc@killer.DALLAS.TX.US (Bob Calbridge) writes:
>Okay, I give up.  What is the function of the archive bit?   Does this
>tell the opsys to do some auditing?  The furschluginner book tells you
>how to set it but not what it's for.
>Also in passing......is there a way to copy protect specific files?
>Even something low level, just to keep the geeks out.
>
>Best,
>Bob

The archive bit is set every time the o/s updates a file.  This is 
useful for backup programs that only want to archive files that have
been modified since the last time they were backed up.  (Read your
DOS manual entry for the backup command for more info.)

There is no easy way to copy protect s/w without getting involved
with non-standard formatting (for floppy disks).  The closest one
can get to copy protecting in a DOS transparent fashion is to have
code that installs the file, and patches some information into the
file that is based on the absolute track/sector location(s) of the
file.  Efforts to copy this file will cause it to be relocated.  Be
aware the disk defragmentation programs will clobber this unless you
set the file's hidden attribute, in which case most will leave it alone.

If you only want to keep novice users from getting at something,
you can mark a file hidden and system, which will keep it out of
dir and copy.

Caveat on these two ideas is that if the file is on a floppy disk, 
diskcopy will still copy it.  (Also, to open a file with hidden or
system attribute, you have to set the file attributes used for the 
open call to match the file's.)


Simcha Lerner
harvard!humming!simcha