The PC's Space Program                                by Gene Plantz

       I've  often wanted just a bit more room on a start-up floppy disk to
    store more of my favorite programs.  Before I installed my hard disk, I
    attempted  to  transfer the utilities that I used most frequently to my
    start-up disk.  Invariably, I'd need a tad more room.  By  not  placing
    the  desired utilities on that basic disk, I wasted time swapping disks
    when I needed a stray utility program.

       This  cumbersome  process  is no longer necessary.  Spacemaker, from
    Realia, lets you compress the .COM and  .EXE  files  of  your  favorite
    programs   to  conserve  space  on  the  disk.   After  the  files  are
    compressed, you can run the programs as you normally would.  Spacemaker
    is  designed  not  for  novices  but  for active PC users who have more
    floppies - and  less  free  space  -  than  they'd  like.   Programming
    expertise  can  help  you  make  the  most of the utility but it is not
    essential.  The program works on just about any .COM or .EXE file  that
    can  be executed from the DOS prompt.  Application programs, of course,
    require at least one of the two files to function.

       Spacemaker can  also  convert  .EXE  files  to  .COM  files  if  the
    compressed  version  takes up less than 64K.  The advantage of doing so
    is that loading and directory searches are generally  faster  for  .COM
    files  than  for  .EXE files.  To make the conversion from .EXE to .COM
    files, you use Spacemaker as you would the DOS utility  EXE2BIN  (which
    performs  a  function  similar  to Spacemaker's but, unlike Spacemaker,
    alters the file's logical format.).COM  files  are  understood  by  the
    computer  at its most basic level and thus differ from files written in
    source code, which is far more accessible.  The computer  always  loads
    .COM  files into a specific location in memory..EXE files, which can be
    loaded anywhere in RAM depending  on  how  much  memory  is  used,  are
    capable  of  supporting  bigger programs.  Functionally the two are the
    same;  the difference is in how DOS handles them.

       Other file compression programs are on the market, but  none  allows
    you  to  leave  the  program  compressed  and  still use it;  most file
    compression programs require that you reconstitute the  program  before
    running  it.   HOW  THE  PROGRAM WORKS:  Spacemaker reads your .COM and
    .EXE files, then produces fresh .COM or  .EXE  files  that  retain  the
    original files' information.  The program compresses binary zeros as ti
    reformats the file.  The result is a smaller file that is equivalent in
    every  way  to  the  original program file except that superfluous disk
    space has been eliminated.

       The Spacemaker process actually adds code  to  the  beginning  of  a
    program  file.   This  code is called the "loader." It reconstructs the
    program file in memory to its precompression form.  This loader routine
    uses little space and is hardly noticeable when the program is running.
    The routine is designed to work when the program is  loaded  under  DOS
    (via  COMMAND.COM).  This means that virtually any program you initiate
    from the DOS command prompt is a candidate for compression.

       You  start  Spacemaker  by   providing   the   program   with   file
    specifications,  such  as  the names of the input and output files.  If
    anything is  missing  the  program  will  ask  you  for  the  necessary
    information.   To  compress  a  program,  you  simply  give the command
    SPACEMKR INFILE OUTFILE, with INFILE representing the name of the input
    file and OUTFILE representing the name of the output file.

       You  must  use a different name for the output file than you've used
    for the input file.  Spacemaker does not alter the input  file  in  any
    way.   Under  the  program's default settings, .EXE files are input and
    .COM files are output.

       SPACE TO SPARE:  The program's results are noteworthy.  When  I  ran
    Spacemaker  with  the  PC-DOS LINK.EXE program, I recorded a 22 percent
    savings in disk space - about 10K -  upon  completion  of  compression.
    The program file now requires less disk space than it formerly did, and
    being smaller, it also loads faster than before compression.  I've used
    the compressed LINK program for four months without a hitch.

       Although  Spacemaker  is  best  suited to help you get the most from
    floppies, it also enables hard disk  users  to  store  more  files  and
    reduce program load time.  My hard disk, for instance, contains roughly
    700 files.  Using Spacemaker, I compressed 17 .COM files  and  25  .EXE
    files.   The  .COM  files  used  an  average  of  8  percent less space
    following compression;  savings for the .EXE files averaged 15 percent.
    Crunching these 42 files freed up slightly more than 500K.

       Ironically, some files grew slightly after compression.  My bulletin
    board  programs,  written  in  Compiled  BASIC  were  larger  following
    compression.  If the program code doesn't contain many groups of binary
    zeros, there won't be much to compress.  Unfortunately, there is no way
    to  tell  in  advance  whether a file will benefit from the compression
    process.  Other Compiled BASIC programs have realized significant space
    savings from Spacemaker's efforts.

       TO  COMPRESS  OR  NOT  TO  COMPRESS:   As  these  examples  suggest,
    Spacemaker is easy to use and the results can be impressive.  The  only
    difficulty is in determining what you can and cannot compress.

       A  few  programs that start from the DOS prompt - including the word
    processing program MultiMate - did  not  run  after  compression.   And
    compression  will prevent some .COM files from running, including 1-2-3
    utilities like FILEMGR.COM.  But of the hundreds  of  programs  that  I
    compressed,  only ten or so failed to run properly after compression by
    Spacemaker.

       Discussions with the utility's author revealed that a problem  could
    occur  if  a  program's  developers use a linker program other than the
    standard DOS LINK.  The rule is, if a .COM or .EXE file is loaded by  a
    program  other than DOS, you should not attempt to compress it.  If you
    do, you'll lock up your system, lose any new data, and need to reboot.

       The documentation  for  Spacemaker  includes  sufficiently  detailed
    explanations  of what the program does and how it works.  The manual is
    concise and particularly insightful for the technically inclined.

       I found it interesting that the files that Spacemaker compresses are
    hard  to debug.  Conceivably, software developers could use the program
    as a copy-protection technique that avoids unconventional disk  formats
    yet  "hides" code from those who know how to use DOS's DEBUG feature to
    disassemble programs.

       Overall, I found Spacemaker to be an effective means of getting more
    from  less.   Active PC users can, with minimal effort, save both space
    and time.

                      Spacemaker
                      Realia, Inc.
                      10 S.Riverside Plaza
                      Chicago, IL  60606
                      312-346-0642
                      Retail price: $75.00

       Note: there are at least three switches   /O  /N   and  /S
             /O is for converting files complied under DOS 1.0 or 1.1
             /N is for converting files compiled under DOS 2.x or 3.x
             /S functions are unknown