View source for BSArc and BSA

{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={{ext|bsa}}, {{ext|bs2}}, {{ext|bsn}}
|released=1991?
}}
'''.BSA''', '''.BS2''', and '''.BSN''' are compressed archive formats associated with a group of archiving utilities that includes ''BSArc'' (or ''BS ARChiver'') and ''BSA''. They were developed by PhysTechSoft (PTS), a Russian software company better known for the PTS-DOS operating system ([[Wikipedia:PTS-DOS|Wikipedia article]]). BSArc is also credited to Serg Babitchew.

BSArc is for DOS. BSA was apparently available for a number of different platforms: It lists DOS, Windows, OS/2, QNX, and Unix.

== Format details ==
The three file extensions seem to correspond to three distinct file formats. But the software name is not always used consistently. Roughly speaking, the "BSArc" software uses .BSA or .BS2 format, and is generally older than the "BSA" software, which (confusingly) uses .BSN format.

It's not just that the software name was changed; there is a BSArc v2.00 (which uses .BS2 format), and a BSA v2.00 (which uses .BSA format).

== Identification ==
A possible signature for .BSA format is {{magic|0x00 0xAE}} at offset 1, followed by a byte with value {{magic|0x02}}, {{magic|0x03}}, or {{magic|0x07}}.

.BS2 files probably begin with {{magic|0xd4 0x03 'S' 'B' '&nbsp;' 0x00}}.

.BSN files probably begin with signature {{magic|0xff 'B' 'S' 'G'}}. [[IDArc]] says this sequence may also start at offset 1 or 3.

== Software ==
* [http://old-dos.ru/index.php?page=files&amp;mode=files&amp;do=show&amp;id=1421 BSArc at old-dos.ru]
* [http://old-dos.ru/index.php?page=files&amp;mode=files&amp;do=show&amp;id=704 BSA at old-dos.ru]
* [https://www.sac.sk/download/pack/bsfx19.exe BSArc V1.9.3] (DOS software, Russian)
* [http://files.mpoli.fi/software/DOS/COMPRESS/BSA200.ZIP BSA 2.00 Rel 0.972] (DOS software, English)
* [https://www.sac.sk/download/pack/bsa.zip BSA 2.0 Rel 1.10] (DOS software, English)

== Links ==
* [http://phystechsoft.ru/ PhysTechSoft website]