MS-DOS installation compression - Revision history

Jsummers: /* See also */

2024-04-28T14:58:25Z

‎See also

Jsummers: /* See also */ There are too many ".??_" formats to try to list them

2024-04-28T14:57:04Z

‎See also: There are too many ".??_" formats to try to list them

Dexvertbot: /* Sample files */

2023-12-28T04:13:56Z

‎Sample files

JTN: /* Software */ fix my markup

2023-02-28T19:33:45Z

‎Software: fix my markup

JTN: /* Software */ note which Linux tools have compression and decompression; link newer version of mscompress (as packaged by Debian)

2023-02-28T19:33:21Z

‎Software: note which Linux tools have compression and decompression; link newer version of mscompress (as packaged by Debian)

Jsummers at 16:47, 7 January 2023

2023-01-07T16:47:40Z

Jsummers at 16:07, 7 January 2023

2023-01-07T16:07:11Z

Jsummers at 17:22, 20 December 2022

2022-12-20T17:22:49Z

Jsummers: /* Format details */

2022-04-28T22:17:02Z

‎Format details

Jsummers: /* See also */

2021-09-18T15:16:07Z

‎See also

@@ Line 11: / Line 11: @@
 == See also ==
 * [[Microsoft KWAJ installation compression]]
 * [[Microsoft SZ installation compression]]
 == Format details ==

@@ Line 13: / Line 13: @@
 * [[Microsoft KWAJ installation compression]]
 * [[Microsoft SZ installation compression]]
 == Format details ==

@@ Line 37: / Line 37: @@
 == Sample files ==
-* https://telparia.com/fileFormatSamples/archive/msCompress/
+* {{DexvertSamples|archive/msCompress}}
 == Links ==

@@ Line 32: / Line 32: @@
 * [ftp://ftp.microsoft.com/softlib/mslfiles/CP0982.EXE Setup Toolkit for Visual C++]
 * [[7-Zip]]
-* [https://github.com/stapelberg/mscompress mscompress] (ftp://ftp.penguin.cz/pub/users/mhi/mscompress/ original version]) → mscompress, msexpand (compression and decompression)
+* [https://github.com/stapelberg/mscompress mscompress] ([ftp://ftp.penguin.cz/pub/users/mhi/mscompress/ original version]) → mscompress, msexpand (compression and decompression)
 * [https://www.winehq.org/ Wine]
 * {{Deark}}

@@ Line 27: / Line 27: @@
 == Software ==
-* [https://www.cabextract.org.uk/libmspack/ libmspack] → msexpand
+* [https://www.cabextract.org.uk/libmspack/ libmspack] → msexpand (decompress only)
 * EXPAND.EXE - utility included with many versions of MS Windows and MS-DOS
 ** [https://archive.org/details/1996-01-13-windows3.1windowsforworkgroups3.11intl Windows for Workgroups 3.11...] → WFW311/ENG_ARA/EXPAND.EXE - File Expansion Utility v2.10 (for DOS). This version of EXPAND.EXE supports SZDD, as well as KWAJ compression types 2 and 3.
 * [ftp://ftp.microsoft.com/softlib/mslfiles/CP0982.EXE Setup Toolkit for Visual C++]
 * [[7-Zip]]
-* [ftp://ftp.penguin.cz/pub/users/mhi/mscompress/ mscompress] → msexpand
+* [https://github.com/stapelberg/mscompress mscompress] (ftp://ftp.penguin.cz/pub/users/mhi/mscompress/ original version]) → mscompress, msexpand (compression and decompression)
 * [https://www.winehq.org/ Wine]
 * {{Deark}}

@@ Line 3: / Line 3: @@
 |subcat=Compression
 |extensions={{ext|??_}}, {{ext|??$}}
-|pronom={{PRONOM|fmt/462}}, {{PRONOM|fmt/469}}
+|pronom={{PRONOM|fmt/462}}
 }}
-A pair of compression formats by Microsoft that appear on MS-DOS and early Windows (3.x) installation disks; the formats have no generally agreed-upon name. Compressed files may be generated by the COMPRESS.EXE program (appearing in Microsoft's Setup Toolkit for Visual C++), and uncompressed with the EXPAND.EXE program distributed with Windows and MS-DOS. Compressed files have the last character of the file extension replaced with an underscore, or sometimes a dollar sign.
+'''MS-DOS installation compression''' refers to a family of compressed file formats formats by Microsoft that appear on MS-DOS and early Windows (3.x) installation disks. The formats have no generally agreed-upon name. This article is primarily about the format whose files start with "SZDD". For the other formats, see [[Microsoft KWAJ installation compression]] and [[Microsoft SZ installation compression]].
 <!-- There are reports of the Google Chrome installer [http://festiva-yourchoice.blogspot.com/2010/01/expandexe-preventing-google-chrome-from.html needing the EXPAND.EXE program]. -->
 == See also ==
 * [[Microsoft SZ installation compression]]
@@ Line 18: / Line 21: @@
 == Format details ==
-There are two major formats, which can be referred to by their file signatures: "SZDD", and "KWAJ". SZDD is more common. Another variant, sometimes known as "SZ", or the "QBasic variant", is covered in a separate article: [[Microsoft SZ installation compression]].
+SZDD's compression format similar, but not identical, to [[LZSS (Haruhiko Okumura)|Okumura's LZSS]]. There is a byte at offset 8 that specifies the exact type of compression. Most sources say that the only known value for this byte is "A" (0x41), but some report[https://www.betaarchive.com/forum/viewtopic.php?t=26161] that there is also a type "B", used by Windows 3.1 builds 026 and 034e.
-−
-=== SZDD ===
 SZDD's compression format similar to [[LZSS (Haruhiko Okumura)|Okumura's LZSS]]. There is a byte at offset 8 that specifies the exact type of compression. Most sources say that the only known value for this byte is "A" (0x41), but some report[https://www.betaarchive.com/forum/viewtopic.php?t=26161] that there is also a type "B", used by Windows 3.1 builds 026 and 034e.
-−
-=== KWAJ ===
-KWAJ format is somewhat more sophisticated than SZDD. There is a 16-bit field at offset 8 that specifies the compression or encoding method.
-−
-{| class="wikitable"
-!Compression code !! Description
-|-
-|0 || Uncompressed
-|-
-|1 || [[Exclusive Or|XOR]]
-|-
-|2 || [[LZSS]]
-|-
-|3 || [[LZ77 with Huffman coding|LZ77 + Huffman]]
-|-
-|4 || [[MSZIP]] (based on [[DEFLATE]])
-|}
 == Identification ==
-File begin with bytes {{magic|53 5A 44 44 88 F0 27 33}} ("SZDD" variant), or {{magic|4B 57 41 4A 88 F0 27 D1}} ("KWAJ" variant).
+An SZDD file begins with bytes {{magic|53 5A 44 44 88 F0 27 33}}.
 == Software ==

@@ Line 14: / Line 14: @@
 * [[FTCOMP]]
 * [[SQUEEZE (AJP Systems)]]
 == Format details ==