P - C O M P R E S S 2 V1.1   INTRODUCTION  P-Compress2 has been completely re-written in Assembler for System2 (at least 2.04 required) and System3, with a greatly improved user interface and some major new options: * Alternative `SuperC' compression - more efficient, compression slower, decompression a lot slower. * Appicon facility - drop in files, drawers or whole disks for hands-off compression/decompression * Menu alternatives to all gadget inputs. * Configuration file. One facility from the old P-Compress is missing - PACK. This is likely to reappear as a very simple multi-disk archive/backup tool for people who don't like or need the elaborations of current offerings. Compatability with P-Compress (latest version V2.9) is maintained and System 1.3 machines can continue to use this. Like its predecessor it will compress single files, drawers or complete disks, preserving disk and drawer structures. Drawers and disks can be copied from one place to another, selected files or classes of files being compressed and the remainder just copied. P-Compressed files (both standard and SuperC compression), including sounds, pictures and animations, can be displayed by P-Reader V7.1 without prior decompression, and P-Compressed texts (standard compression only) can be loaded into and saved from P-Writer Standard compression is LZH using code by Barthel and Krekel, modified to limit memory requirements. SuperC compression is based on Meixner's innovative SHRINK archiver, with improvement in speed and for most types of file a (very small) gain in efficiency. The penalty for using SuperC is that compression time is considerably increased and roughly equals decompression time.  COMPARISON WITH ALTERNATIVE PROGRAMMES  Archivers: eg LHArc, PKAZip. Archivists are well provided for at present with the fast and efficient LHA and the slower but even more efficient SHRINK. P-Compress2 does not compete in this area, or in the area of HD Backup. General compression tools: eg Power Packer An excellent programme in its day the current PD version of PowerPacker is completely outclassed by practically everything, although the speed of the commercial version may justify some continued use. The NUKE module in the XPK package has a useful balance of speed and efficiency, although the latter is poorer than the standard P-Compress and a long way below SuperC. No two people will ever agree on the optimum balance of speed and efficiency, but it is worth remembering that the PRIMARY function of compression is to save space rather than time.  INSTRUCTIONS  Gadgets and the corresponding menu items are generally interchangeable; the gadgets are described individually, mention only being made of the menu item where its function is different. COMPRESS Click to select compression DECOMPRESS Click to select decompression If neither is selected the input will just be copied to the output FROM Click on the word `FROM' to get a file-requester. TO Click on the word `TO' to get a file-requester. The file names selected will appear in the `from' and `to' string gadgets where they can be modified or changed. Alternately if the file names are known they can be written directly into the string gadgets. Press RETURN after entering each name. If a drawer or disk is entered at FROM, but an existing file at TO, the program will object. If TO is left blank, files will be compressed/decompressd to the current directory. You can compress or decompress back over the original - enter the same reference in both FROM and TO. To give a measure of protection an inter- mediate file is used (ram:m). COMPRESSION SETTINGS DATA FILES The required operation (compression or decompression) will be carried out if the file selected is a data file, or on any data files in the selected drawer. EXEC FILES As above, but for executables (a definition which includes such files as libraries and handlers). ICONS As above, but for icons. Files of types not selected will just be copied. ASK If a drawer or disk is being handled the program will pause at each file and ask for instructions. STRIP Executable files will be stripped of hunks that are not needed in normal operations (such as debug or symbol hunks). Hunks lost cannot be restored. STRIP can be combined with compression, but not with decompression. SUPERC Selects higher efficiency compression. ACTION CHANGE COLORS Clicking the requester cycles through the available colors. Yhat the equivalent menu items select a color-table directly. CANCEL Clears all flags and entries. OVERWRITE Allows existing files to be overwritten with new data. If this flag is not set the program will ask for instructions before overwriting. GO Click to start the operation. A 'Progress' window will open to tell you what is happening. (Fatal warnings, or notices that require an answer will come up in requesters rather than in this window). OPEN COMPICON Clicking this closes the main screen and opens an Appicon (named CompIcon) on WorkBench which can then be used to compress or decompress in accordance with the set flags. See the section COMPICON below. QUIT Quit. There are two additional menu items: Save Flags Saves flag and color settings to a file "P-Compress.pref" in your S: directory. About Puts up a small window with some information about the program.  COMPICON  To use the CompIcon first open P-Compress2 normally, select Compress or Decompress, and if compressing set the compression flags as necessary. Click Open Compicon. The main screen will close and the CompIcon will appear on the Workbench screen (Workbench must be open). If you now drop any icon into into the Compicon the files called by the icon (single file, drawer or disk) will be compressed or decompressed in accordance with the set flags. Note that the Overwrite flag will be set automatically. A window will be opened to keep you informed of progress. When the Compicon is no longer required double-click it to reopen the main window.  GENERAL  The space available on a disk or hard-disk partition is checked when necessary, and if it appears insufficient you will be asked for instructions. For very small files it may be worth continuing (click OK), otherwise click QUIT. Before decompressing compressed files a checksum (CRC) is read and checked - if an error is found an appropriate warning will be given and the offending file passed over. If a file is found to be compressed by PowerPacker (other than self- executing program files) it will automatically be decompressed before the called-for operation - compression, decompression, or just copying - is carried out. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ P-Compress is Freeware. It may be copied and distributed freely and used without charge for non_commercial purposes. Authority for commercial use should be obtained from the author below. No responsibility can be accepted for any loss occasioned by use of these programmes. Comments, suggestions, bug-reports all welcome. Chas A. Wyndham, 1265 Canning Mills Road, Roleystone, WA 6111. Australia