Realia Spacemaker

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(Created page with "{{FormatInfo |formattype=electronic |subcat=Compression |subcat2=Executable compression |released=1982? }} '''Realia Spacemaker''' (or just '''Spacemaker''') is an executable ...")
 
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It compresses [[DOS executable (.com)|COM]] files (to COM), and [[MS-DOS EXE|EXE]] files (to EXE or COM).
 
It compresses [[DOS executable (.com)|COM]] files (to COM), and [[MS-DOS EXE|EXE]] files (to EXE or COM).
 +
 +
== Discussion ==
 +
Two versions have been found: 1.03 and 1.06. They create files that are slightly different. All compressed files found in the wild seem to be consistent with having been made by one of these two versions.
 +
 +
For an EXE file to be compressible by Spacemaker, it should have the following properties:
 +
* The header field at offset 2, "bytes in last page", must ''not'' be 0, due to a bug.
 +
* The header field at offset 12, "max allocation", must be 0xffff.
 +
* The header field at offset 26 must be 0.
 +
* No overlay.
  
 
== Identification ==
 
== Identification ==
−
(Only version 1.06 has been evaluated.)
+
For COM format, the first 18 bytes match the pattern:
  
−
Compressed COM files apparently start with bytes {{magic|9c 55 56 8c cd 83 c5}}, and have ASCII "{{magic|MEMORY$}}" at offset 18.
+
9c 55 56 8c cd 83 c5 10 8d b6 ?? ?? 56 be ?? ??
 +
56 cb
  
−
Compressed EXE files apparently have {{magic|9c 55 56 8c cd 83 c5}} at offset 512, and ASCII "{{magic|MEMORY$}}" at offset 530.
+
In pristine files, this is followed by the ASCII string "{{magic|MEMORY$}}".
 +
 
 +
For EXE format, the same pattern appears at the start of the ''code image'' segment (refer to [[MS-DOS_EXE#Special file positions]]), which is probably always offset 512 in pristine files.
 +
 
 +
It is possible to distinguish between version 1.03 and 1.06.
 +
 
 +
It is possible to determine the original format, COM or EXE. For instance, if the original format was EXE, there are 9 consecutive 0x90 bytes in the decompressor code. Exception: The "<code>/S</code>" option makes it impossible to tell that the original format was EXE.
  
 
== Software ==
 
== Software ==
 +
* Spacemaker v1.03:
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** [https://ftp.hanmesoft.com/HOBBES/DEC/rainbow/msdos/misc/spacemkr.lzh spacemkr.lzh]
 +
** [https://archive.org/details/ftp.update.uu.se.2014.03 archive of ftp.update.uu.se] → pub/rainbow/msdos/misc/spacemkr.lzh
 +
** [{{DiscMasterURL|browse/11758/ftp.update.uu.se.2014.03.zip/ftp.update.uu.se/pub/rainbow/msdos/misc/spacemkr.lzh}}]
 +
** [{{DiscMasterURL|browse/29984/wbiz0000-0009/wbiz0004.tar/wbiz0004/EXE2COM.ARC}}]
 +
** [https://archive.org/details/the-cia-world-fact-book The CIA World Fact Book...] → SEL/12/0048/EXE2COM.EXE
 
* Spacemaker v1.06:
 
* Spacemaker v1.06:
 
** {{OldskoolDOSEXE}} → DOSEXE Executable Tools Pack → packers/spacemaker.106-realia.rar
 
** {{OldskoolDOSEXE}} → DOSEXE Executable Tools Pack → packers/spacemaker.106-realia.rar
 
** [https://vetusware.com/download/Realia%20Spacemaker/?id=4297 At Vetusware]
 
** [https://vetusware.com/download/Realia%20Spacemaker/?id=4297 At Vetusware]
 +
* {{Deark}}
 +
 +
== Sample files ==
 +
* {{CdTextfiles|simtel/stmsdos9709/disk1/DISC1/DIRUTL/DATER11.ZIP|DATER11.ZIP}} → DATER.COM (v1.03 EXE→COM)
 +
* {{CdTextfiles|pcsig08/101_200/DISK0191/DISK0191.ZIP|DISK0191.ZIP}} → DVED.COM (v1.03 COM→COM)
 +
* {{CdTextfiles|pdos9606/GAMES/ROLEPLAY/NHPLUS.ZIP|NHPLUS.ZIP}} → GETYN.COM (v1.03 EXE→COM)
 +
* [https://archive.org/details/shareware-grab-bag Shareware Grab-Bag] → 090/dutils.arc (v1.06; some EXE→COM, some COM→COM)
 +
* {{CdTextfiles|swextrav1993/disk2/business/ck2.zip|ck2.zip}} → C*.EXE (v1.03)
 +
* {{CdTextfiles|swextrav1993/disk3/prntutil/canset11.zip|canset11.zip}} → *.EXE (v1.06)
 +
* {{DexvertSamples|archive/spaceMakerPacked}}
  
 
== Links ==
 
== Links ==

Latest revision as of 17:50, 20 March 2026

File Format
Name Realia Spacemaker
Ontology
Released 1982?

Realia Spacemaker (or just Spacemaker) is an executable compression utility for DOS, developed by Realia. It was possibly the first executable compression utility for DOS to be released.

It compresses COM files (to COM), and EXE files (to EXE or COM).

Contents

[edit] Discussion

Two versions have been found: 1.03 and 1.06. They create files that are slightly different. All compressed files found in the wild seem to be consistent with having been made by one of these two versions.

For an EXE file to be compressible by Spacemaker, it should have the following properties:

  • The header field at offset 2, "bytes in last page", must not be 0, due to a bug.
  • The header field at offset 12, "max allocation", must be 0xffff.
  • The header field at offset 26 must be 0.
  • No overlay.

[edit] Identification

For COM format, the first 18 bytes match the pattern: 

9c 55 56 8c cd 83 c5 10 8d b6 ?? ?? 56 be ?? ??
56 cb

In pristine files, this is followed by the ASCII string "MEMORY$".

For EXE format, the same pattern appears at the start of the code image segment (refer to MS-DOS_EXE#Special file positions), which is probably always offset 512 in pristine files.

It is possible to distinguish between version 1.03 and 1.06.

It is possible to determine the original format, COM or EXE. For instance, if the original format was EXE, there are 9 consecutive 0x90 bytes in the decompressor code. Exception: The "/S" option makes it impossible to tell that the original format was EXE.

[edit] Software

[edit] Sample files

[edit] Links

Retrieved from "http://fileformats.archiveteam.org/index.php?title=Realia_Spacemaker&oldid=51589"
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