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MSLI SL SLIMSL IM IM IMSLIMSL LI LIMSLI MS MS IMS LIM IM SL SL SL MS MS MS LI LIM SLI SL SL IM IMSL SLIM LI LI MS MSLIM SLIMS IM IM SL SL MSL SLI SL MSL MS LI LI LIMSLI LI LIMSLIM SL IM IM MSLI IM MSLIMSL LI MS MS LI MS LIM IM SL SL SL MS MS LI LI LI SL SL IM IM IM LI LI MS MS MS IM IM IM SL SL SL MSL IMS MS LI LI LI LIMSLIMS SLIMSLIMSL SLIMSL IM IM MSLIMS LIMSLIMSLI LIMSLI MS MS _______ _______ _____________________ ___________ S L I M F i l e C o m p r e s s i o n S y s t e m _______ _______ _____________________ ___________ U s e r M a n u a l Version 1.10A Copyright (C) Dominic Herity 1988,1991 _______ ____|__ | (R) --| | |------------------- | ____|__ | Association of | | |_| Shareware |__| o | Professionals -----| | |--------------------- |___|___| MEMBER S L I M U s e r M a n u a l Pg 1 Copyright (C) Dominic Herity 1988,1991 All rights reserved This software and manual are supplied "as is" and without warranties as to performance or merchantability. This software is supplied without any expressed or implied warranties whatsoever. No warranty of fitness for a particular purpose is offered. Any liability of seller or manufacturer will be limited exclusively to product replacement or refund of the purchase price. Dominic Herity further reserves the right to alter the specifications of the software and contents of the manual without obligation to notify any person or organization of such alterations. SLIM is a "shareware program", and is provided at no charge to the user for evaluation. Feel free to share it with your friends, but please do no give it away altered or as part of another system. If you find SLIM useful, and that you continue to use it after a reasonable trial period, you must make a registration payment to the author. All registered users will receive a copy of the latest version of SLIM, along with the other benefits of registration. See Section 10 of this manual for more information. Commercial users of SLIM must register and pay for their copies of SLIM within 30 days of first use, or their license is withdrawn. Site license arrangements may be made by contacting Dominic Herity. Anyone distributing SLIM for any kind of remuneration must have authorization from Dominic Herity at the address below. Authorization will be automatically granted to associate members of the Association of Shareware Professionals. Authorized distributors will receive prompt upgrades. Dominic Herity, PO Box 3038, Dublin 4, Ireland. CompuServe: 100016,3477 Internet: 100016.3477@compuserve.com This program is produced by a member of the Association of Shareware Professionals (ASP). ASP wants to make sure that the shareware principle works for you. If you are unable to resolve a shareware-related problem with an ASP member by contacting the member directly, ASP may be able to help. The ASP Ombudsman can help you resolve a dispute or problem with an ASP member, but does not provide technical support for members' products. Please write to the ASP Ombudsman at P.O. Box 5786, Bellevue, WA 98006 or send a Compuserve message via easyplex to ASP Ombudsman 70007,3536 S L I M U s e r M a n u a l Pg 2 A C K N O W L E D G E M E N T S Thanks to LJF Berenson, Adrian Bivar, John Cockings, Kam Ho, Panos Milonas, Alan Pink, Sam Smale, Charles Stross, Peter Tetley, Bertold Tromm and Charles P White, for bug reports and/or suggestions for improvement of SLIM. I was encouraged by their enthusiasm and constructive criticism. Many thanks to Brian Doody, Kevin McGoldrick, Imelda Herity, Michael Feehily, Tony McGinty and Kieran Boyce, each of whom contributed helpful suggestions and observations to this product. All thanks to my wife, Teresa, for all her help, support, encouragement and faith when I spent evenings and weekends stuck in front of a computer with no visible results. S L I M U s e r M a n u a l Pg 3 C O N T E N T S Section Subject Page 1.0 Introduction 4 2.0 Getting Started 5 3.0 Compressing Files 8 4.0 Accessing Compressed Files 11 5.0 De-compressing Files 15 6.0 Technical Information 16 7.0 Error and other Messages 17 8.0 Technical Support 19 9.0 Version History 20 10.0 Registration 21 S L I M U s e r M a n u a l Pg 4 1.0 I N T R O D U C T I O N SLIM is a powerful file compressor with RAM resident transparent expander, which gives painless access to compressed files. This is done by intercepting DOS calls, allowing applications to read compressed files just as before. So there is no need to worry about technicalities like archives. Just put a command to load SLIM into the AUTOEXEC.BAT file and forget it. A proprietary algorithm significantly compresses almost all the files found on PCs and gives big savings on disk space. More than half of SLIM Ver 1.00 and 1.01 users who responded to a questionnaire said that SLIM allowed them to postpone or cancel a hard disk upgrade. A report facility shows which of a group of files are compressed, by how much and with what total savings. SLIM's compact size (less than 24KB) makes it practical for floppy as well as hard disk machines. The RAM resident part of SLIM uses 73KB of main memory. System Requirements: IBM PC or MSDOS machine, MSDOS Ver 2.00+, 256K+ RAM S L I M U s e r M a n u a l Pg 5 2.0 G E T T I N G S T A R T E D This is for people who want to get on with using SLIM and read about it later. If you are new to SLIM, read on. If you are upgrading from an older version of SLIM, go to section 2.2. 2.1 NEW USERS OF SLIM _________________ To get SLIM up and running, you need only one file, SLIM.EXE. This contains all the functions of a working system. Copy SLIM.EXE your hard disk. The root directory is recommended. If you do not have a hard disk, copy SLIM.EXE onto any system (boot) disks you will use to boot your machine before accessing compressed files. It is not necessary to have SLIM.EXE on all disks with compressed files, if you only need to read the files. If your system disk has a file AUTOEXEC.BAT, add a line to the file, with the text : "SLIM ON". This ensures that every time your computer is powered on, compressed files can be accessed normally. If you do not have a file AUTOEXEC.BAT, create one with the same line. C>TYPE AUTOEXEC.BAT SLIM ON C> Re-boot your system (Ctrl-Alt-Del). The following message will appear when AUTOEXEC.BAT runs. C>SLIM ON S L I M F i l e C o m p r e s s i o n S y s t e m V1.10 Copyright (C) 1988,1991 Dominic Herity. Loading SLIM de-compressor C> This indicates that the RAM resident part of SLIM is now loaded. This is needed to allow you to access compressed files. It is also needed to de-compress compressed files (see section 5). As SLIM now occupies 72KB of RAM which was previously available for programs, some larger programs may not run with SLIM loaded. This is more of a problem with systems containing 256K RAM, but if your machine has 512K or more, you should have no difficulty. Watch out for applications reporting "insufficient memory", "program too big to fit in memory" or not running after SLIM is loaded. Lack of RAM is the most likely cause of such a failure. Now your system is ready to handle compressed files. All you have to do now is compress some, and start saving disk space (or expanding your disk, if you prefer to see it that way). S L I M U s e r M a n u a l Pg 6 Pick one or more files for compression. As this is a familiarization exercise, take a small one (say, between 5000 and 30000 bytes), since compressing large files takes a lot of time. The file selected should also be one that you read often, but write to seldom or never. An EXE or COM file is a good candidate on this basis, but these don't compress as well as text or program source code. Spreadsheets and database files compress best, but they tend to be too large for our present purposes. DON'T select a file that you need before SLIM is turned on, e.g. COMMAND.COM or SLIM.EXE, as SLIM will refuse to compress these. (See section 3 for more details.) Also, ensure that you have at least as many bytes free on your disk as the file you wish to compress, because SLIM needs workspace to compress a file. Let's assume you chose to compress the DOS utility program FIND.EXE. (I suggest this because it gives unusually good results, at least in PC-DOS Version 3.00.) Type : C>SLIM FIND.EXE SLIM displays a byte counter when compressing the file and reports the saving when it is finished. C>SLIM FIND.EXE S L I M F i l e C o m p r e s s i o n S y s t e m V1.10 Copyright (C) 1988,1991 Dominic Herity. Original Compressed Save Bytes Bytes (%) File (Press any key to abort) 6363 1019 83% C:FIND.EXE 6363 bytes reduced to 1019 in 1 files saving 5344 (83%) 360448 bytes free out of 20971520. SLIM is RESIDENT and ACTIVE. C> In the unlikely event that SLIM cannot compress the file, pick another one. Most files are compressible. So you have liberated some disk space from FIND.EXE. Now try to use the compressed file. C>FIND "SLIM" <AUTOEXEC.BAT SLIM ON C> As you can see, FIND.EXE works just as before. SLIM works on all sorts of files just as easily, word processor documents, spreadsheets, ASCII files, and peculiar unique files used by various software packages. S L I M U s e r M a n u a l Pg 7 To see if a file or set of files is compressed, and by how much, use the SLIM R command. For example : C>SLIM R DOS\*.* S L I M F i l e C o m p r e s s i o n S y s t e m V1.10 Copyright (C) 1988,1991 Dominic Herity. Original Compressed Save Bytes Bytes (%) File (Press any key to abort) 6363 1019 83% DOS\FIND.EXE 8544 4044 52% DOS\SHARE.EXE 15123 9882 34% DOS\ATTRIB.EXE 3629 2539 30% DOS\SYS.COM 33659 bytes reduced to 17484 in 4 files saving 16175 (48%) 96256 bytes free out of 20971520. SLIM is RESIDENT and ACTIVE. C> But before you get carried away, glance through the rest of this manual. You could read it while SLIM crunches up some of those monstrous files that have been hogging your disk. 2.2 UPGRADING FROM AN EARLIER VERSION OF SLIM _________________________________________ SLIM V1.10 behaves pretty much the same as versions 1.00 and 1.01. It just does it faster and better. Files compressed with the earlier versions can be used the same as before. However, SLIM V1.10 compresses somewhat better than its predecessors, so you might find it worthwhile to expand and re-compress the old files. See Section 9 for more information on changes. All copies of your earlier version of SLIM should be removed from where they might be used inadvertently. If you have stray extra copies of SLIM.EXE lying around, now would be a good time to get rid of them. The main reason for this is to avoid one version of SLIM being loaded and another being used afterwards. If two versions of SLIM from V1.10 on are mixed in this way, SLIM outputs an error message and refuses to work. The message reads "A different version of SLIM has been loaded. Use one only". Removal of old versions is particularly important for versions 1.00 and 1.01. This is because the method of communicating with a previously loaded RAM resident part (loaded by 'SLIM ON') has been changed in Version 1.10. So, for example, a V1.00 RAM resident part will not realize that SLIM V1.10 is 'family' and will expand files when an access is attempted. This would make SLIM V1.10 take compressed files to be uncompressed. So confusion results. See Section 4 for more information on the function and behavior of the RAM resident part of SLIM. S L I M U s e r M a n u a l Pg 8 3.0 C O M P R E S S I N G F I L E S 3.1 BASIC OPERATION _______________ Before files can be compressed, SLIM must have been loaded by the SLIM ON command. This is because the compression process performs a check using the RAM resident de-compressor, to guard against internal bugs which might prevent later access to a compressed file. Files can be compressed by entering : C>SLIM [n] filespec where 'filespec' is a filename including optional path. More than one file can be compressed if wildcards ('*' or '?') are included in the filespec. SLIM will take each file matching the filespec and attempt to compress it. '[n]' is an optional number 0 to 9 which alters the 'thoroughness' of the attempt to compress the file(s). This will not normally be used, but see section 3.3 below for more information. As SLIM compresses each file, it displays a byte count indicating the progress of compression. If you want SLIM to skip a file, press any key and SLIM will abandon the file on the next counter update and proceed to the next file. When a file has been compressed, the original and compressed sizes are displayed on screen, as in the SLIM R command. If SLIM encounters a file which is already compressed, it will bypass it. When all files have been processed, SLIM displays a summary of bytes saved and total bytes and bytes free on the disk. See example below. C>SLIM DOS\*.* S L I M F i l e C o m p r e s s i o n S y s t e m V1.10 Copyright (C) 1988,1991 Dominic Herity. Original Compressed Save Bytes Bytes (%) File (Press any key to abort) 6363 1019 83% DOS\FIND.EXE 8544 4044 52% DOS\SHARE.EXE 15123 9882 34% DOS\ATTRIB.EXE 3629 2539 30% DOS\SYS.COM 33659 bytes reduced to 17484 in 4 files saving 16175 (48%) 96256 bytes free out of 20971520. SLIM is RESIDENT and ACTIVE. C> S L I M U s e r M a n u a l Pg 9 3.2 DISK SPACE REQUIRED ___________________ SLIM needs some workspace on disk to compress files. When compressing, it reads the original file and produces the compressed file, before deleting the original. To do this, SLIM needs up to as much free disk space as the largest file to be compressed. If SLIM runs out of disk space while compressing a file, it will output an error message, leave the file uncompressed and proceed to the next file. If you are short of free disk space and wish to compress a number of files, some small and some large, compressing the small files first may free enough disk space to allow the large files to be compressed. 3.3 COMPRESSION THOROUGHNESS ________________________ When compressing files, SLIM can be instructed to 'try harder' or 'hurry up' by specifying a compression thoroughness parameter. This is done by inserting a number between 0 and 9 before the filespec. For example : C>SLIM 7 *.EXE will compress all .EXE files in the current directory with a thoroughness parameter of 7. The parameter defaults to 5 if not specified. A higher value means a longer runtime and (possibly) better compression performance. A lower value means shorter runtime and (possibly) worse compression. These results are not guaranteed, however, and it may happen that a file compressed with a parameter of 6 is actually larger than one compressed with a parameter of 5. In addition for larger parameter values, runtime tends to double for each increment in parameter value, with little or no improvement in compression. For these reasons, it is usually best to leave this parameter alone. It should be reserved for when you badly need better compression on a particular file, or use a low value to quickly squash a few files to give you some temporary disk space. 3.4 INCOMPRESSIBLE FILES ____________________ Occasionally, SLIM will encounter a file whose 'compressed' size is actually larger than the original. When this happens, SLIM leaves the file uncompressed and outputs a message saying that it cannot compress the file. 3.5 RUNTIME _______ File compression take a long time compared to the small delay on access. Fortunately, compression is an infrequent task and only needs to be repeated when new files are added to the disk or when files have been written to. Files which are frequently written to should not be compressed. The short term gain of disk space is outweighed by the time taken to re-compress the file and the inconvenience of running compression often. S L I M U s e r M a n u a l Pg 10 Large quantities of files can be compressed overnight using a batch file. If the batch file is still running when you need the machine again, it can be safely interrupted by pressing Ctrl- Break. The batch file can be re-started later and SLIM will quickly skip over files already compressed. Here are some example batch files for compressing large numbers of files. C>TYPE SLIM1.BAT REM COMPRESS ALL FILES IN WS DIRECTORY C:\SLIM C:\WS\*.* C> C>TYPE SLIM2.BAT REM COMPRESS ALL FILES IN : REM WS, WS\DATA, SYMPH, SYMPH\DATA, DBASE, DOS ETC. C:\SLIM \WS\*.* C:\SLIM \WS\DATA\*.* C:\SLIM \SYMPH\*.* C:\SLIM \SYMPH\DATA\*.* C:\SLIM \WS\*.* C:\SLIM \DBASE\*.* C:\SLIM \DOS\*.* C:\SLIM \XTREE\*.* C> C>TYPE SLIM3.BAT REM COMPRESS ALL FILES IN : REM WS, WS\DATA, SYMPH, SYMPH\DATA, ETC. FOR %%X IN ( WS WS\DATA SYMPH ) DO C:\SLIM \%%X\*.* FOR %%X IN ( SYMPH\DATA DBASE DOS XTREE ) DO C:\SLIM \%%X\*.* C> The last of these examples is the most useful. By customizing SLIM3.BAT to your own machine's directory structure, you can compress all the files in some or all of your directories. The batch file can be re-run at intervals to catch any new or rewritten files. When you change your directory structure, edit the batch file accordingly. 3.6 FORBIDDEN FILES _______________ Compressed files can only be correctly read when SLIM is activated, using the SLIM ON command. This command would typically be in the AUTOEXEC.BAT file. But certain files must be read on power up, before SLIM is activated. Examples are COMMAND.COM, CONFIG.SYS and of course, SLIM.EXE. If any of these files were compressed, the computer could not power up properly. To prevent this, SLIM refuses to compress any files with a ".SYS" extension and any files called COMMAND.COM, IBMBIO.COM, IBMDOS.COM, AUTOEXEC.BAT or SLIM.EXE. If SLIM encounters any of these files during compression, it outputs a message saying the file should not be compressed. S L I M U s e r M a n u a l Pg 11 4.0 A C C E S S I N G C O M P R E S S E D F I L E S 4.1 CONFIGURING YOUR SYSTEM WITH SLIM _________________________________ To ensure access to compressed files, enter the command 'SLIM ON' in your AUTOEXEC.BAT file. Make sure that this command occurs before any commands that access compressed files. For example, if you compress SK.COM, and you have the command SK in AUTOEXEC.BAT, you must place the 'SLIM ON' command before the 'SK' command. If you do not wish to have SLIM permanently loaded, which may be the case if you have an application that needs lots of memory, make sure to enter the SLIM ON command before attempting access to any compressed files. Once SLIM is loaded into memory by the SLIM ON command, it cannot be removed, except by restarting the computer (Ctrl-Alt-Del). 4.2 HOW COMPRESSED FILES ARE ACCESSED _________________________________ Once loaded, SLIM gives automatic access on demand to compressed files. It does this by intercepting any calls a program (including COMMAND.COM) makes to DOS. Normally, SLIM passes these calls straight on to DOS, but when a call is detected which opens a compressed file, SLIM reads the file and makes a full size copy on disk for the program to use. It then changes the name of the compressed file to a name it recognizes itself and renames the new full size file to the original file name. Only then does it pass the call on to DOS. Neither DOS nor the program know that this is happening, so operation is completely automatic. When an expanded file is closed without being modified, SLIM (equally quietly) deletes the expanded copy and renames the original compressed file to its original name. If a program modifies an expanded copy of a file, SLIM deletes the compressed original and leaves the expanded new file on disk. Compressed files may be renamed without affecting access. Compressed files can also be deleted. If a compressed file is copied to another file with SLIM ON, the new file will be a full size, not a compressed, copy of the original. 4.3 COPYING AND BACKING UP COMPRESSED FILES _______________________________________ In some circumstances, you may wish to manipulate files without expanding them. Copying and backing up files are such circumstances. The command SLIM OFF is provided for this reason. It prevents SLIM from expanding files when opened, but does not remove SLIM from memory or prevent it expanding a COM or EXE file when it is run. S L I M U s e r M a n u a l Pg 12 Do not forget to turn SLIM ON again when the copying or backup is complete. If in doubt, an extra SLIM ON command will not hurt. To see if SLIM is ON or OFF enter the command SLIM and the status will displayed, INACTIVE meaning OFF and ACTIVE meaning ON. If you mistakenly access a file with SLIM OFF or not loaded, the file will not make sense, but the error will be obvious. Most programs report in a fairly civilized manner when a file is not what they expect. If the compressed file is accessed as an ASCII or text file, the file will seem to contain the message '= sLiM' and nothing else. If a program in a compressed COM file is mistakenly run without SLIM loaded, the program will stop immediately. 4.4 DISK SPACE __________ Because SLIM makes a full size copy of each file that is accessed, there must be enough disk space free to accommodate all the full size copies that will be need at any one time. This does not, however, include full size copies of COM or EXE files that are being run, as these are deleted immediately when their contents are loaded into memory. This can be illustrated by the following example. C>SLIM R *.* S L I M F i l e C o m p r e s s i o n S y s t e m V1.10 Copyright (C) 1988,1991 Dominic Herity. Original Compressed Save Bytes Bytes (%) File 46080 39720 13% WSOVLY1.OVR 25600 19563 23% WS.COM 32256 18004 44% WSMSGS.OVR 19840 8473 57% DOCUMENT.TXT 123776 bytes reduced to 85760 in 4 files saving 38016 (30%) 106596 bytes free out of 20971520. SLIM is RESIDENT and ACTIVE. C> I will run WS.COM (a well known word processor) to edit the file DOCUMENT.TXT. The files WS.COM, WSOVLY1.OVR and WSMSGS.OVR are compressed, as is DOCUMENT.TXT. WS.COM uses data in WSOVLY1.OVR and WSMSGS.OVR, so it accesses these. So my disk must have at least 46080 + 32256 + 19840 = 98176 bytes free. (More accurately, it must have 48K + 32K + 20K = 100K bytes free, since data is stored on the disk in units no smaller then 2K.) I don't need 25600 bytes for WS.COM as this is only expanded transiently, until loaded into memory. But I do need to have 25600 bytes free just to run WS.COM. S L I M U s e r M a n u a l Pg 13 Don't panic! You do NOT need a calculator to use SLIM. The above information is provided so that you will know (a) what is happening, if it happens, and (b) what must be done to stop it happening. If you prefer, do what you did last time you ran out of disk space - start deleting files. When SLIM runs out of disk space on expansion, it returns an 'Access denied' error as a response to the DOS call, but the message on screen may not make this obvious. For example, if you try to execute a compressed .EXE file, and SLIM fails to expand it, the message that appears on screen is 'Bad command or file name'. SLIM will also be unable to expand a file if the file is in the root directory of a disk and the root directory is full. A little known peculiarity of DOS is that the root directory of a disk (for example A:\) can store only a limited number of directory entries (filenames). The limit is normally 112 for a 360K floppy disk and 512 for a hard disk. Since the volume label occupies one directory entry, the practical limit is 111 and 511 respectively. Sometimes people find this out the hard way when they try for example to copy 200 1K files onto a floppy disk. If a compressed file is in a full root directory, SLIM will fail to produce an expanded copy. To check if this is the cause of failure, try copying files (with SLIM turned OFF) and if this fails even though enough disk space is free, a full directory is the probable cause. A remedy to a full root directory is to copy all or some files into a sub-directory (after freeing enough space to create the sub-directory). Even if you do not need the files to be compressed, a nearly full root directory is likely to cause further trouble. Do not put a write protect tab on a floppy disk if you want to access compressed files on that disk, as this prevents generation of an expanded copy. This is not a problem, however, if you only use the disk for file storage. The file may be copied from the write protected disk with SLIM turned OFF, and then accessed on an unprotected disk, with SLIM turned ON. 4.5 TRANSPARENCY FAILURES _________________________ SLIM gives programs the illusion that small files are big files. It does this very successfully and almost all of the software is fooled all of the time. But there are some cases where the illusion cannot be maintained and compression must be either avoided or done carefully. The first case is where a program obtains the size of a file from its directory entry and then reads that number of bytes when it opens the file. The intention is to read the whole file, but if the file is compressed, only the number of bytes that the compressed file occupies are read. This behavior has been seen with the DOS XCOPY command (Ver 3.21 at least) and PKZIP (Ver 1.01 at least) from PKWARE. A solution is to change the name of the offending program and S L I M U s e r M a n u a l Pg 14 replace it with a batch file that turns SLIM off, runs the program, and turns SLIM on again. For example : C>TYPE XCOPY.BAT REM REM XCOPY WITH SLIM OFF. REM PREVENTS TRUNCATION AND PRESERVES COMPRESSION. REM SLIM OFF OLDXCOPY %1 %2 %3 %4 %5 %6 %7 %8 %9 SLIM ON C> The second case where SLIM confuses other software is a particular copy protection method. The method bypasses DOS to read the disk area in which the program is presumed to be stored, to check it is still there. The details of where this is on the user's disk is written into the program by an installation program. If an ordinary copy of the program is run, it will see that its own code is not in the expected place on disk. It then 'knows' that an unauthorized copy is being used. Variations on this theme use other files apart from the program file or check the file allocation table instead of the data area of the disk. Programs copy protected by these means tend to have warnings in the documentation against copying the program file or files. When SLIM compresses a file, it reads the original, writes a new file on a different area of disk and deletes the original. This causes the copy protection method to be activated. The obvious remedy here is to not compress files subject to such a copy protection scheme. If you must compress such files, it may be possible to get an unprotected copy of the software from the vendor. Since copy protection has become unpopular, it is not likely that this problem will happen with any new software you acquire. S L I M U s e r M a n u a l Pg 15 5.0 D E - C O M P R E S S I N G F I L E S 5.1 BASIC OPERATION _______________ The SLIM X (eXpand) command de-compresses a file or set of files. This command can only be used if SLIM has been made RAM resident with the SLIM ON command. Example : C>SLIM X DOCUMENT.TXT S L I M F i l e C o m p r e s s i o n S y s t e m V1.10 Copyright (C) 1988,1991 Dominic Herity. Original Compressed Save Bytes Bytes (%) File 19840 8473 57% DOCUMENT.TXT 19840 bytes were reduced to 8473 in 1 files saving 11367 (57%) 83968 bytes free out of 20971520. SLIM is RESIDENT and INACTIVE. C> 5.2 DISK SPACE REQUIRED ___________________ For SLIM X to execute correctly, enough free disk space must be available to store an expanded file as well as the compressed file, because the compressed file is only deleted after the de- compressed file is produced. S L I M U s e r M a n u a l Pg 16 6.0 T E C H N I C A L I N F O R M A T I O N 6.1 FILES USED BY SLIM __________________ Using SLIM, you will occasionally glimpse files with strange names lurking on your disk. SLIM uses files called 'SLIMnnnn.$$$' where nnnn is a four digit decimal number. The other files are the compressed originals of open files (See Section 4.2). These will be seen if, for example, you call up a directory display in a word processor whose working files are compressed. If you see any files of the type 'SLIMnnnn.$$$' when you are SURE that you do not have any compressed files open (for example, on power up), this indicates power loss or other failure when the file was being accessed. Rename the file to something else (e.g. WHATISIT.FOR) and use the SLIM R command to see the original file size. If that size is the same as that of another file in the same directory, then WHATISIT.FOR is probably the compressed original of that file. If you are sure that WHATISIT.FOR is not an older version of a revised file, rename it to the filename of your choice and continue to use it. Otherwise, delete it. 6.2 RAM RESIDENT INTERFACE ______________________ When SLIM is loaded, the RAM resident part is kept in memory. It is necessary for the non-resident part to communicate with it for a number of reasons. One reason is to turn it on and off. Another is to verify (after compressing a file) that a file can be accessed. This is a safety measure to protect against a bug in SLIM, which virtually guarantees that SLIM will never cause loss of data. A third reason is to use the RAM resident part to expand a compressed file (X command). The interface to SLIM's RAM resident part supports the TesSeRact(TM) Standard for Ram-Resident Program Communication. For information about TesSeRact, contact the TesSeRact Development Team at: TesSeRact Development Team c/o Chip Rabinowitz 2084 Woodlawn Avenue Glenside, PA 19038 1-215-884-3373 Compuserve: 70731,20 MCIMAIL: 315-5415 This MCIMAIL Account has been provided to the TesSeRact Development Team by Borland International, Inc. The TesSeRact Development Team is in no way associated with Borland International, Inc. TesSeRact is a trademark of the TesSeRact Development Team. S L I M U s e r M a n u a l Pg 17 7.0 E R R O R A N D O T H E R M E S S A G E S There follows an alphabetically sorted list of error messages produced by SLIM, with (as appropriate) some information on probable cause and references to this manual for further information. MESSAGE : A different version of SLIM has been loaded. CONTEXT : At startup CAUSE : Two versions (at least) of SLIM.EXE are present. One was loaded earlier (SLIM ON) and the other has been run. FURTHER INFORMATION : Section 2.2 MESSAGE : aborted CONTEXT : After failed compression of a file CAUSE : User hit a key, abandoning compression FURTHER INFORMATION : Section 3.1 MESSAGE : Can't compress this file CONTEXT : After failed compression of a file CAUSE : File size can't be reduced FURTHER INFORMATION : Section 3.4 MESSAGE : Can't expand this file CONTEXT : Failed expansion of compressed file CAUSE : Not enough free disk space to make expanded copy. FURTHER INFORMATION : 5.2 MESSAGE : Can't open (filename) CONTEXT : During compression, expansion or reporting CAUSE : File was found but could not be opened. FURTHER INFORMATION : MESSAGE : Can't open new file CONTEXT : At start of file compression CAUSE : Full disk or directory FURTHER INFORMATION : Section 3.2 MESSAGE : Can't write to output file CONTEXT : During file compression CAUSE : Disk full FURTHER INFORMATION : Section 3.2 MESSAGE : Insufficient Memory CONTEXT : At SLIM startup CAUSE : Not enough memory available for SLIM to run FURTHER INFORMATION : Section 1 MESSAGE : Internal Error : Can't compress this file CONTEXT : At end of file compression CAUSE : SLIM internal error. Should not occur FURTHER INFORMATION : Section 8 - Please contact the author S L I M U s e r M a n u a l Pg 18 MESSAGE : Loading SLIM de-compressor FURTHER INFORMATION : Section 4.1 MESSAGE : No files CONTEXT : At SLIM startup, compressing, expanding or reporting on files. CAUSE : No files were specified for processing. FURTHER INFORMATION : Section 2.0, 3.1, 5.1 MESSAGE : Should not compress this file CONTEXT : At start of file compression. CAUSE : SLIM refuses to compress file. FURTHER INFORMATION : Section 3.6 MESSAGE : SLIM de-compressor already off FURTHER INFORMATION : Section 4.3 MESSAGE : SLIM de-compressor already on FURTHER INFORMATION : Section 3.1, 4.3 MESSAGE : SLIM de-compressor not loaded FURTHER INFORMATION : Section 4.3 MESSAGE : SLIM de-compressor turned off FURTHER INFORMATION : Section 4.3 MESSAGE : SLIM de-compressor turned on FURTHER INFORMATION : Section 3.1, 4.3 MESSAGE : SLIM must be loaded to do compression or expansion. CONTEXT : Attempt to expand or compress files. CAUSE : For these commands to be used, it is necessary for SLIM to be RAM resident first. (SLIM ON command.) FURTHER INFORMATION : Sections 3.1, 5.1 MESSAGE : PC-DOS or MS-DOS Version 2.00 or greater required CONTEXT : SLIM startup. CAUSE : You are using an old version of DOS (Ver1.xx). FURTHER INFORMATION : Section 1 MESSAGE : Write error on output CONTEXT : After file compression. CAUSE : Disk full. FURTHER INFORMATION : Section 3.1 S L I M U s e r M a n u a l Pg 19 8.0 T E C H N I C A L S U P P O R T 8.1 SUPPORT POLICY ______________ I have good reason to believe that my software is more reliable than most in the computer industry, and I intend to keep it that way. If you have a problem with SLIM, that means that either there is a bug in the software or the manual is misleading. In either case, I want to know about it. I gladly offer a free upgrade of SLIM to any registered user for a usable bug report (whether it was reported previously or not). If you don't have a problem, but have suggestions or comments, I'd like to see them. 8.2 WHAT TO SEND ____________ If you are reporting some abnormal behavior by SLIM, I will probably need to see it to be of any help. The more complete the information you provide, the quicker and more helpful my response can be. Ideally, you should send a floppy disk with a README file containing your explanation of the problem. It should also include copies of all files involved. If I can see a bug, I'm most of the way to fixing it. I undertake to use any files received in this way for debugging only and to destroy all copies when that is done. Please make sure the problem still happens when you boot your system without an AUTOEXEC.BAT or CONFIG.SYS file. If you can make it happen using only the files on the floppy disk you are sending, and not your hard disk, then it is fairly sure that I can reproduce the problem. It is usually easier to include a batch file than to explain what to type. Please mention what DOS version you use (MSDOS or PCDOS with numbers), your machine (manufacturer, CPU type, RAM. etc.), and anything else you think may be relevant. S L I M U s e r M a n u a l Pg 20 9.0 V E R S I O N H I S T O R Y Version : 1.00 Released : November 1988 This is the initial release of SLIM. Version : 1.01 Released : April 1989 The shareware version previously demonstrated compressibility of files larger than 64K. Since this can be time-consuming, large files are now skipped over. Licensed version behaves as before. Version : 1.10 Released : February 1991 Compression is typically many times faster for large files (over 64KB approx.). Expansion is at least 50% faster for large files. Bigger savings for small files. Compression is improved significantly. Users of earlier versions should re-compress their files when convenient. Work space on disk used when compressing files reduced to half. SLIM.EXE is reduced from over 30KB to less than 22KB. Shareware edition of SLIM now compresses files of unlimited size. Various bugs fixed. S L I M U s e r M a n u a l Pg 21 10.0 R E G I S T R A T I O N 10.1 THE PITCH _________ Registration of SLIM will entitle you to : * A licensed copy of the version current at registration time * A printed manual for same * Application support from the author * Notification of future upgrades * The chance to order these upgrades at a large discount * Free upgrade if released within 3 months of registration If you believe that SLIM enhances your computer, or if you want the latest update, or if you would like first refusal of future enhancements at a special price, please register now. The next page contains an order form and optional questionnaire which you should print out, fill in and mail to me. You can also order via e-mail on CompuServe or Internet, with a credit card. SLIM registration costs 45 US dollars per machine with no funny business. That means that disk, manual and shipping worldwide by airmail are included in the price. I rely on your support. Inquiries about site licenses are welcome. If you are a software developer worrying about the size of files your application uses, SLIM could save your time, your money and your sanity. S L I M U s e r M a n u a l Pg 22 10.2 SLIM ORDER FORM _______________ (PLEASE USE BLOCK CAPITALS) Title (Mr/Ms) : ____ Surname : __________________ Personal Name : __________________ Company : __________________ (if license for company, rather than personal use.) Address : _________________________________________ _________________________________________ _________________________________________ _________________________________________ _________________________________________ Number of licensed copies of SLIM required at $45.00 each : ____ Disk (please tick one, 5.25" by default) : 5.25" ____ 3.5" ____ Method of payment (please tick one) : Access/EuroCard/Mastercard/Visa ____ American Express ____ Cheque (your country's currency) ____ Bank Draft (US$) ____ If payment by credit card, please supply following information : Card number ____________________ Expiry Date ______________ Signature (if order on paper) ______________________________ Charge per copy is 45 U.S. dollars or equivalent, including registration, printed manual, postage and packing. If payment is by cheque in your country's currency, please ensure that payment is sufficient and allow for exchange rate variation. Please do NOT send a eurocheque for U.S. dollars OR a U.S. dollar cheque drawn on a non-U.S. bank. This order may be mailed to : Mr Dominic Herity, PO Box 3038, Dublin 4, Ireland. Electronic credit card orders may be sent to : CompuServe 100016,3477 or internet 100016.3477@compuserve.com. Thank you. Please see questionnaire on following pages. S L I M U s e r M a n u a l Pg 23 10.3 QUESTIONNAIRE _____________ This questionnaire is entirely optional. You may ignore it or fill it in partially or fully and return it with your order. But I would be obliged if you would take a few minutes over it to help me improve SLIM to meet your needs better. 10.3.1 YOU What is your profession ? ___________________ How often do you use your computer ? (Please tick one) Occasionally____ Daily____ Much of time____ 10.3.2 YOUR COMPUTER Manufacturer ___________________ Model ___________________ CPU (Circle one) 8088 8086 80286 80386 V20 V30 Other (please specify) ___________________ Speed(MHz) ___________________ RAM(KB) ___________________ Hard Disk Capacity (MB) ___________________ Floppy drives : Number ____ Capacity (KB) ____ Form Factor (Circle one) 5.25" 3.5" 10.3.3 YOUR APPLICATION What do you mainly use your computer for ? (Circle one or more) Word processing Spreadsheets CAD Database Accounts Software Dev't Desktop Publishing Games Other (please specify) ___________________ List the software packages that you use most often 1 ___________________ 4 ___________________ 2 ___________________ 5 ___________________ 3 ___________________ 6 ___________________ 10.3.4 YOUR USE OF SLIM How did you acquire your shareware copy of SLIM ? e.g. friend, shareware company (please specify) ___________________ Approximately how much disk space do you expect to save ? ___________________bytes reduced to ___________________ What types of files do you expect to make the savings on ? (Circle one or more) Word processor ASCII text EXE and COM files Database Spreadsheets Graphics Other (please specify) ___________________ S L I M U s e r M a n u a l Pg 24 Approximately what range of file sizes do you wish to compress ? From ___________________ to ___________________ bytes Please rank these potential improvements for SLIM in your order of choice __ Faster compression __ Faster expansion/access __ Automatic re-compression of files written to __ More compression/smaller compressed files __ Less disk workspace used by SLIM when compressed files are being accessed. __ Other (please specify) ___________________ __ Other (please specify) ___________________ How do you rate this manual (Circle one) Very Bad Bad Fair Good Excellent Please Indicate any parts of this manual which are unclear or difficult : __________________________________________________________ Has SLIM enabled you to postpone or cancel upgrading your hard disk ? (Circle one) Yes No Please list any other file compression utilities you know, whether you have used them, and any comments you have on them. __________________________________________________________ __________________________________________________________ __________________________________________________________ 10.3.5 YOUR COMMENTS Any suggestions for product improvement, complaints about shortcomings, etc. would be much appreciated, however small you may consider them. Attach a separate sheet if necessary. __________________________________________________________ __________________________________________________________ __________________________________________________________ _____________________________