ARJ
(More info about expiration) |
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| Line 18: | Line 18: | ||
Some beta versions inexplicably print "CRC error!" if they're expired. | Some beta versions inexplicably print "CRC error!" if they're expired. | ||
| − | At least one version prints a message about a time delay, but then | + | At least one version prints a message about a time delay, but then seems to hang forever. |
Newer versions have a time delay whose duration depends on how long ago they expired. The delay can be several minutes. | Newer versions have a time delay whose duration depends on how long ago they expired. The delay can be several minutes. | ||
| Line 48: | Line 48: | ||
== Identification == | == Identification == | ||
| − | An ARJ archive starts with signature bytes {{magic|0x60 0xea}}. | + | An ARJ archive starts with signature bytes {{magic|0x60 0xea}}. Byte <code>0x02</code> appears at offset 10. |
The full identification algorithm used by the ARJ software is given in its technical documentation. | The full identification algorithm used by the ARJ software is given in its technical documentation. | ||
| Line 81: | Line 81: | ||
** {{CdTextfiles|simtel/simtel20/MSDOS/ARCHIVRS/UNARJ241.ZIP|v2.41}} (1993-04) - Source code + DOS binary | ** {{CdTextfiles|simtel/simtel20/MSDOS/ARCHIVRS/UNARJ241.ZIP|v2.41}} (1993-04) - Source code + DOS binary | ||
** [https://www.sac.sk/download/pack/unarj265.exe v2.65] (2002-06) - Source code + DOS binary + Windows console binary | ** [https://www.sac.sk/download/pack/unarj265.exe v2.65] (2002-06) - Source code + DOS binary + Windows console binary | ||
| + | * ARJCRYPT - An add-on required to enable the "new" encryption method | ||
| + | ** arjc270.exe: [http://www.filegate.net/pub/compress/arjc270.exe], [https://toogam.com/software/archive/archiver/arj/arjc270.exe] | ||
| + | ** arj32c3i.exe: [http://www.filegate.net/pub/compress/arj32c3i.exe], [https://toogam.com/software/archive/archiver/arj/arj32c3i.exe] | ||
* [[7-Zip]] | * [[7-Zip]] | ||
* [http://arj.sourceforge.net/ Open-source ARJ] | * [http://arj.sourceforge.net/ Open-source ARJ] | ||
Revision as of 17:54, 7 June 2022
ARJ is a compressed archive format, and associated software. It was developed by Robert Jung.
Contents |
Discussion
ARJ was one of the leading compression tools during the 1990s. While it was a bit slower than PKZIP, it sported many more options, some of which were unique during that time (archives over multiple disks/volumes, fine-tuning of the compression algorithms used based on the data that was being compressed, recovery records to recover from simple transmission errors, etc.).
ARJ software expiration
If you wish to use or research the official ARJ software, be aware that some of the free/evaluation and beta versions of ARJ and ARJ32 have a hard-coded expiration date. They do not work, or do not work as well, if they think they are being used after that date. Expiration can manifest in several ways.
The 0.xx versions disable some features, based on the system clock, and the timestamp of the file being archived. Other versions only seem to care about the system clock.
Some beta versions inexplicably print "CRC error!" if they're expired.
At least one version prints a message about a time delay, but then seems to hang forever.
Newer versions have a time delay whose duration depends on how long ago they expired. The delay can be several minutes.
The newest versions that don't expire are apparently ARJ 2.76 and ARJ32 3.09.
Suggest running expired DOS versions in DOSBox-X, which lets you set the clock.
Format details
Compression methods
| ID | Name | Description |
|---|---|---|
| 0 | stored | No compression |
| 1 | compressed most | LZ77+Huffman. For decompression purposes, these are all more-or-less compatible with LHA's "lh6" method. |
| 2 | ... | |
| 3 | ... | |
| 4 | compressed fastest | LZ77 |
| 8 | no data, no CRC | |
| 9 | no data |
Identification
An ARJ archive starts with signature bytes 0x60 0xea. Byte 0x02 appears at offset 10.
The full identification algorithm used by the ARJ software is given in its technical documentation.
See also
Specifications
- The ARJ/UNARJ distributions include detailed format information, in a file named TECHNOTE.TXT or similar.
- A copy of the 2001-09 version (with an addendum of some sort)
- The ARJ Archive File Format, from fileformat.info and Corion.net
Software
- ARJ - Official compression/decompression software for DOS
- ARJ32 - Official compression/decompression software for Windows console
- v3.04 (1999-12-19)
- v3.20 (2012-01-02)
- Various versions at old-dos.ru
- UNARJ - Official software, decompression only
- ARJCRYPT - An add-on required to enable the "new" encryption method
- 7-Zip
- Open-source ARJ
- Konvertor
See also the notes about software expiration, elsewhere on this page.
Sample files
- http://cd.textfiles.com/20mnn/HPTEXT/PHRACK/
- The Silver Collection CDs have many ARJ files
- http://cd.textfiles.com/goldmedal/
