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by setting the ARCTEMP environment string with the MS-
DOS SET command.  For example, if drive B: is your
RAMdisk, then you would type:

    set ARCTEMP=B:

Refer to the MS-DOS manual for more details about the
SET command.  You need only set the ARCTEMP string
once, and ARC will use it from then on until you
change its value or reboot your system.


If ARC does not find an environment string named
ARCTEMP, then it looks for one named TEMP to use
instead.  Several packages already use the TEMP string
for exactly this purpose.  If you have need of an
environment string named TEMP for something else, then
you should be sure to define ARCTEMP.


There are a limited number of temporary files created
by ARC.  The Convert command uses a file named
"$ARCTEMP.CVT" to hold each file as it is being
converted.  The Run command also creates a temporary
file, which has the name "$ARCTEMP", and whose
extension matches that of the file being run.





















ARC                                             Page 18
             MARC



MARC is a separate program which is used to merge
archives created by ARC.  MARC moves files from one
archive to another without unpacking them.


MARC is used as follows:

    MARC <target> <source> [<template> . . .]

Where:

    <target> is the name of the archive to add files
    to.

    <source> is the name of the archive to read files
    from.

    <template> is one or more file name templates.
    The wildcard characters "*" and "?" may be used.
    If no template is supplied, then all of the files
    in <source> are added to <target>.

It is not necessary for the target to exist.  If it
does not exist, then it is created.  Thus, MARC can be
used as an "extractor" as well as a "merger".


For example, if you wanted to create an archive named
"JUNK.ARC", which is to contain all of the files with
an extension of ".TXT" which are currently contained
in another archive named "WASTE.ARC", then you could
type:

    MARC junk waste *.txt

If you wanted to create an archive named "JUNK.ARC",
which is to contain all of the files currently in the
archives "WASTE.ARC" and "TRASH.ARC", you could type:

    MARC junk waste
    MARC junk trash


If MARC is invoked with no arguments, then it gives
brief directions in its use.





ARC                                             Page 19
             ARCE



ARCE is a program which is used to extract files from
an archive.  It will *only* extract files, and it will
*not* extract encrypted files.  It doesn't do anything
that ARC can't do, but it is highly optimized for the
sole purpose of archive extraction, so it is very
small and very fast.

ARCE is used in a fashion very similar to the "ARC E"
command (hence the name).  The first argument is the
name of the archive to extract files from, and may
include a drive and path specifier.  Up to sixteen
additional arguments can be supplied, which specify
the files to extract.  The wildcard characters "*" and
"?" are allowed, as with ARC.  If no files are named,
then all files are extracted from the archive.  If the
file being extracted already exists, you are asked
whether or not you want to overwrite it.  You can use
the "/R" option to bypass this.

For example, if you had an archive named "WASTE.ARC"
that you wanted to extract everything from, then you
could type:

    ARCE waste

Or if you just wanted to extract the files with a
filename extension of ".ASM", you could type:

    ARCE waste *.asm

If you already have a few files from the archive that
you want replaced, then you could type:

    ARCE waste *.asm /R

If you run ARCE with no arguments at all, then it will
give you a brief reminder of how to use it.


NOTICE:NOTICE: ARCE is the copyrighted property of Vernon D.
        Buerg and Wayne Chin.  It is included on the
        ARC program disk as a service to ARC users.

        Vernon D. Buerg
        456 Lakeshire Drive
        Daly City, CA  94015
        RBBS: [phone]



ARC                                             Page 20
        VERSION NUMBERS



There seems to be some confusion about our version
numbering scheme.  All of our version numbers are
given as a number with two decimal places.

The units indicate a major revision, such as adding a
new packing algorithm.

The first decimal place (tenths) indicates a minor
revision that is not essential, but which may be
desired.

The second decimal place (hundredths) indicates a
trivial revision that will probably only be desired by
specific individuals or by die-hard "latest version"
fanatics.

ARC also displays its date and time of last edit.  A
change of the date and time without a corresponding
change in version number indicates a truly trivial
change, such as fixing a spelling error.


To sum up: If the units change, then you should get
the newer version as soon as you can.  If the tenths
change, then you may want to get the newer version,
but there's no hurry.  If anything else changes, then
you probably shouldn't bother.























ARC                                             Page 21
 COMMON QUESTIONS AND ANSWERS



Here are some of the more common questions we've
received about ARC, along with their answers:


Q: Why does ARC run out of room if I make an archive
   bigger than about 180k?

A: Because you are working on a floppy disk.  ARC
   creates a copy of your archive, incorporating any
   new files as it goes.  When it is done, it deletes
   the original and renames the new one.  There are a
   number of reasons for doing it this way, one being
   that your original archive is still intact if
   anything happens while ARC is running.

   You can save some space by using drive specifiers
   and having the archive and the files to add on
   separate disks, but you still won't be able to make
   an archive larger than about 180k.  If you need to
   make a larger archive, and if you have a fixed
   disk, then you can create the archive on the fixed
   disk and then copy it to the floppy.


Q: I've seen an ARC.COM and an ARC.EXE.  Which one is
   the right one?

A: ARC.EXE.  One or more people have been running ARC
   through a utility that converts an ".EXE" file to a
   ".COM" file.  But this utility is designed to save
   space, not speed.  On ARC it saves about 250 bytes,
   and makes no measurable difference in program
   speed.  We've decided that the savings are not
   worth the extra step in development in this case.


Q: How can I get the latest version of ARC?

A: ARC updates are distributed through normal
   shareware channels, and by FidoNet.  We also ship a
   program update disk on every order of $50 or more.
   Also, please refer to the next section for
   information about our maintenance contracts.







ARC                                             Page 22
Q: Can I use ARC to distribute my public domain or
   shareware program?

A: Yes, of course.


Q: Can I use ARC to distribute my commercial software
   package?

A: Yes, provided that you obtain a commercial
   distribution license from us.  Please contact us
   for details.


Q: I'm a commercial user.  Why should I pay for
   shareware that others get for free?

A: Because you cannot credibly plead poverty.
              ___   Shareware, all shareware, is an attempt to develop
   a new marketing channel to the benefit of everyone.
   You can still "test drive" shareware for a short
   period, but if you decide to use it in your
   business, then you should pay for it.


Q: Why not allow me to select which method of
   compression I want ARC to use?

A: It would needlessly complicate ARC, both internally
   and in use.  The exact nature of the compression
   methods used are complex, and quite different.  The
   only sure way to tell which will be best in any
   given case is to analyze the data, as ARC does.
   The method chosen may not always be what you
   expect.



















ARC                                             Page 23
     MAINTENANCE CONTRACTS



Registered users of ARC receive 90 days of telephone
support at no extra charge.  If you wish, you can
extend this by pruchasing a maintenance contract.

A maintenance contract costs $50 per year and entitles
you to unlimited telephone support, as well as free
updates to ARC as they come out.











































ARC                                             Page 24
       REVISION HISTORY



CHANGES IN VERSION 3

The function used to calculate the CRC check value in
previous versions has been found to be in error.  It
has been replaced with the proper function.  ARC will
still read archives created with earlier versions of
ARC, but it will report a warning that the CRC value
is in error.  All archives created prior to version
3.0 should be unpacked and repacked with the latest
version of ARC.


Transmitting a file with XMODEM protocol rounds the
size up to the next multiple of 128 bytes, adding
garbage to the end of the file.  This used to confuse
ARC, causing it to think that the end of the archive
was invalidly formatted.  This has been corrected in
version 3.01.  Older archives may still be read, but
ARC may report them to be improperly formatted.  All
files can be extracted, and no data is lost.  In
addition, ARC will automatically correct the problem
when it is encountered.



CHANGES IN VERSION 4

ARC is adding another data compression technique in
this version.  We have been looking for some technique
that could improve on Huffman squeezing in at least a
few cases.  So far, Lempel-Zev compression seems to be
fulfilling our fondest hopes, often achieving
compression rates as much as 20% better than
squeezing, and sometimes even better.  Huffman
squeezing depends on some bytes being more "popular"
than others, taking the file as a whole.  Lempel-Zev
compression is instead looking for strings of bytes
which are repeated at various points (such as an end
of line followed by spaces for indentation).  Lempel-
Zev compression is therefore looking for repetition at
a more "macro" level, often achieving impressive
packing rates.

In the typical case a file is added to an archive once
and then extracted many times, so the increased time
for an update should more than pay for itself in
increased disk space and reduced transmission time.



ARC                                             Page 25
CHANGES IN VERSION 4.1

Lempel-Zev coding has been improved somewhat by
performing non-repeat compression on the data before
it is coded (as was already done with Huffman
squeezing).  This has the two fold advantage of (a)
reducing to some extent the amount of data to be
encoded, and (b) increasing the time it takes for the
string table to fill up.  Performance gains are small,
but noticeable.

The primary changes are in internal organization.  ARC
is now much "cleaner" inside.  In addition to the
aesthetic benefits to the author, this should make
life easier for the hackers out there.  There is also
a slight, but not noticeable, improvement in overall
speed when doing an update.



CHANGES IN VERSION 4.3

Version 4.3 adds the much-demanded feature of using
pathnames when adding files to an archive.

Version 4.3 is also using a slightly different
approach when adding a file to an archive.  The end
result is twofold:

1) Slightly more disk space is required on the drive
   containing the archive.  This should only be
   noticeable to those creating very large archives on
   a floppy based system.

2) A 30% reduction in packing time has been achieved
   in most cases.  This should be noticeable to
   everyone.

As always, version 4.3 is still fully upwards
compatible, and is backwards compatible as far as
version 4.1.













ARC                                             Page 26
CHANGES IN VERSION 4.4

The temporary file introduced in version 4.3
occasionally caused problems for people who had not
added a FILES= statement to their CONFIG.SYS file.
This has now been corrected.  Also, support of the
ARCTEMP environment string was added to allow placing
of the temporary file on a RAMdisk.

A bug was reported in the Run command, which has been
fixed.  From the nature of the bug, and the extreme
time required before the bug was reported, it is
deduced that the Run command is probably the least
used feature of ARC.

The Update command was changed.  It is no longer a
straight synonym for Add.  Instead, Update now only
adds a file if it is newer than the version already in
the archive, as shown by the MS-DOS date/time stamp.



CHANGES IN VERSION 4.5

The Convert command was not making use of RAMdisk
support.  Now it is.

The Freshen command was added.  Our first choice for a
name was Refresh, but we already had a Run command.
Assuming that you have an archive which already
contains everything you want in it (for software
distribution, perhaps), then Freshen would be used to
update the archive.  It was pointed out to us that ARC
already knows what is in the archive, so it should be
able to look on disk for newer versions.  Now it can.

The Suppress compression option was added by popular
demand.  It allows files to be added quickly to an