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From: pollarda@physc1.byu.edu
Newsgroups: comp.compression
Subject: Self Extracting Files
Message-ID: <309pollarda@physc1.byu.edu>
Date: 15 Jun 91 00:53:59 GMT
Lines: 45


PKZip as well as several other file compression utilities I have seen
have the option to have the files self extracting.  I understand that
the files have the machine code to self extract along with the data
combined somehow.  But how exactly does it work?

What tells the computer to stop loading in the file as machine code
and handle the rest as data?

What codes are needed to be able to achieve this?  And what changes
are needed to be made to the program in order for it to work on
this kind of file?

Does anyone have any ideas?

While I am at it, a friend has shown me something else quite curious
and I have told him I would try to find out what is going on. . .

Some programs have something embeded in them so that if you "type"
them, they will display the program name and the material will stop
scrolling on the screen and the DOS prompt will appear again.

e.g.

C:> type program.exe

The Software
(c) 19xx The Software Co.

C:>

If there is anyone with the answer (or at least a good guess at one)
to either of these two questions, I would greatly appreciate it
if you could let me know what is going on.  Both of these have me
Stumped...

Thanx a bunch,

Art Pollard

BitNet: PollardA@Xray.Byu.Edu
Uncle Sam's Express:
600 N. 195 E. #31, Provo, UT. 84606
Phone Stuff:
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