               Acorn Risc OS Port of InfoZip's Zip v2.0j
               -------------------------------------------

                                           by: Karl Davis and Sergio Monesi


Introduction
------------

This is a command-line version of the InfoZip group's machine-independent
Zip program.
Why use Zip - Spark is better? The Zip routines in this distribution
are better than Spark in a number of ways:
* Portability - the files produced are able to be de-archived on many
  hundreds of computer platforms
* Speed - the routines in Zip, especially deflate, produce a much better
  compression over a wider variety of files than the ARC-procedures in
  Spark.
* Security - a Non-US distribution of this release will have, or can
  have, a crypt routine, which is much more secure than that used in
  Spark. This is in turn able to be read, with the correct pass phrase,
  on the aforementioned hundreds of computer platforms.

Unfortunately, InfoZip is a CLI (Command Line Interpreter) program. You
will have to learn how to type. Running it in a taskwindow will maintain
multitasking, though.

Source
------
Acorn Risc OS source files will appear as part of the normal infozip
releases. Simply compiling them should suffice, as the machine type
and details are noted on compilation, and the bits for unix, mac etc
are not used.

Executables
-----------
Released versions of Zip and Unzip, with assorted utilities, will
shortly appear as executables at:
ftp://zonk.geko.com.au/pub/acorn/infozip/zip
ftp://zonk.geko.com.au/pub/acorn/infozip/unzip
with everything else in
ftp://zonk.geko.com.au/pub/acorn/infozip/
as zipfiles.
BINARY TRANSFERRING these files to your Acorn (ftp, DOS discs, etc),
filetyping as 'Absolute' and command-line running them should enable
you to de-archive the remaining files, including the source files and
other tools.

Compiling
---------

This release is able to be compiled with Acorn's Desktop C version 4
and hopefully later versions.
    [It has not been tested, but should also work with GNU GCC.]
Before compiling, run the !RunMe1st obey file in the Acorn directory. It
will move the files from the foo/c to the c.foo for the Acorn compiler.
       ( Alternatively, if you already use InfoZip on your Acorn, )
       (  see the specific usage instructions about Unzip$Exts    )
With the Acorn Desktop C compiler and linker, typing 'amu' in the
main zip directory will compile the programs. If you used
the Unzip$exts option to pull out the C code, then make sure you
copy the makefile from the acorn directory to the main zip directory
before attempting amu.

Acorn-specific usage instructions
---------------------------------

An extra option ('I') has been added to the Acorn port: if it is specified
zip will not consider Image files (eg. DOS partitions or Spark archives when
SparkFS is loaded) as directories but will store them as single files. This
means that if you have, say, SparkFS loaded, zipping a Spark archive will 
result in a zipfile containing a directory (and its content) while using the
'I' option will result in a zipfile containing a Spark archive. Obviously
this second case will also be obtained (without the 'I' option) if SparkFS
isn't loaded.

When adding files to a zipfile; to maintain FileCore compliance, all
files named "file/ext" will be added to the archive as "file.ext".
This presents no problem if you wish to use UnZip to unzip them on any
other machine, as the files are correctly named. This also presents no
problem if you use the accompanying UnZip we have ported, as the files
are converted back to "file/ext" format. The only problem appears when 
you use Spark to decompress the files, as a file called "file.ext" will
be extracted as "file_ext", not what it was added as. You must be careful
about this.

Case Specific. Depending on how you type the command, files will be added
exactly as named; in this example:
*zip new/zip newfile
*zip new/zip NewFile
*zip new/zip NEWFILE
will create an archive containing 3 copies of the same Risc OS file 'newfile'
called 'newfile', 'NewFile' and 'NEWFILE'. Please be careful.

The Acorn port conserves file attributes, including filetype, so if you
zip on an Acorn, and unzip on another Acorn, filetypes will be maintained
precisely as if you used uncompressed files. If you de-archive on another
machine (PC, Mac, Unix etc..), filetypes will be ignored, but the files
will be identical despite this.

An additional feature went into this port to cope better with C-code
and extensions. This allows the acorn files "c.foo" to be added to the
archive as "foo/c", eventually appearing in the archive as "foo.c", allowing
for better handling of C or C++ code. Example:
*Set Zip$Exts "dir1:dir2:dir3"
*zip new/zip dir1.file
*zip new/zip dir2.help
*zip new/zip dir3.textfile
Creates a zipfile new/zip, with entries file.dir1, help.dir2, textfile.dir3.
The usual settings for Zip$Exts are "h:o:s:c", allowing C code to be added
to the archive in standard form.

A final note about the Acorn port regards the use of the 'n' option: this is
used to specify a list of suffixes that will not be compressed (eg. .ZIP,
since it is already a compressed file). Since RISC OS uses filetypes instead
of suffixes, this list of suffixes is actually considered as a list of
filetypes (3 hex digit format). By default, Zip doesn't compress filetypes
DDC (Archive, Spark or Zip), D96 (CFS files) and 68E (PackDir).

Bugs
----
Known  :
        None.
Unknown:
        Please feel free to contact the authors regarding Acorn-specific
        Bugs, at either of their email addresses, or the InfoZip-bugs
        group using zip-bugs@wkuvx1.wku.edu.

Updates
-------
5th April 1995:  Documented 'I' and 'n' options in this file. Fixed bug that
                 prevented directories to be removed using the 'm' option.
                 Repackaged distribution archives.
16th April 1995: Added support for DDEUtils module (to allow more than one
                 zip to run in different TaskWindows and different 
                 directories).

Additions/Changes
-----------------
        Suggestions for alterations or additions are welcome, but if
        they're concerned with things to do with the Acorn port
        specifically, please email the authors directly. If, however,
        there is something you'd like to see changed in the overall
        InfoZip senario, or something you want added, then send it to
        info-zip@wkuvx1.wku.edu
        Although there is no specific copyright maintaining over this
        port, we'd prefer it if you didn't release altered versions of
        it, seeing as we have to answer all the questions when things
        go wrong.

Contacting the Authors
----------------------


Sergio Monesi                              Karl 'RiscMan' Davis
Via Trento e Trieste 30                    PO BOX B23
20046 Biassono (MI)                        Boronia Park 2111
Italy                                      AUSTRALIA
----------------------------               --------------------------------
pel0015@cdc8g5.cdc.polimi.it               riscman@geko.com.au
sergio@freebsd.first.gmd.de                http://www.geko.com.au/riscman/
sergio@phantom.com                         RiscMan@f510.n712.z3.fidonet.org
