Asc2Com
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== Format details == | == Format details == | ||
| − | Version 2.00+ has an option to compress the embedded text with [[LZW]]. | + | |
| + | === Compression scheme === | ||
| + | Version 2.00+ has an option to compress the embedded text with [[LZW]]. Here are some notes on the compression scheme. | ||
| + | |||
| + | Code size is 9 to 10 bits. Special codes: | ||
| + | |||
| + | {| class="wikitable" style="font-size: 85%;" | ||
| + | | 256 || Unused or unknown. | ||
| + | |- | ||
| + | | 257 || Increment code size (from 9 to 10). Seek to the next byte boundary. | ||
| + | |- | ||
| + | | 258 || Stop. | ||
| + | |} | ||
| + | |||
| + | The first dynamic code is 259. The code table is never cleared. | ||
| + | |||
| + | The Asc2Com documentation includes some very minimal information about its LZW format. | ||
== Identification == | == Identification == | ||
| − | + | Most versions (except the very early ones) offer 5 or 6 different "listers", i.e. templates for the generated COM file, with different feature sets. Files made by a particular version, using a particular lister, have a fairly consistent format, and can readily be identified. But there are many versions of Asc2com (some of which might be lost), and a combinatorial explosion of formats. | |
| + | |||
| + | Not every version+lister combination represents a unique format, but there are still a few dozen essentially different formats to deal with. So, precisely identifying and analyzing Asc2Com files can take significant effort. | ||
Generated files usually contain one of the following ASCII strings somewhere in them: | Generated files usually contain one of the following ASCII strings somewhere in them: | ||
| Line 30: | Line 48: | ||
== Software == | == Software == | ||
| + | Encoding/decoding: | ||
| + | |||
* Asc2Com | * Asc2Com | ||
| − | ** {{CdTextfiles|somuch/smsharew/UTIL1/ASC2COM.ZIP|v1.10b}} | + | ** {{CdTextfiles|somuch/smsharew/UTIL1/ASC2COM.ZIP|v1.10b}} (or [https://archive.org/details/msdos_festival_ASC2COM at Internet Archive]) |
** v1.25 and v1.25b (no copy found) | ** v1.25 and v1.25b (no copy found) | ||
** {{CdTextfiles|rbbsv3n1/atnu/asc2com.zip|v1.30}} | ** {{CdTextfiles|rbbsv3n1/atnu/asc2com.zip|v1.30}} | ||
| Line 43: | Line 63: | ||
** {{CdTextfiles|pier01/035a/a2c201.zip|v2.01}} | ** {{CdTextfiles|pier01/035a/a2c201.zip|v2.01}} | ||
** {{CdTextfiles|psl/pslv2nv10/UTILS/DOS/FILEVIEW/ASC2COM.ZIP|v2.05}} | ** {{CdTextfiles|psl/pslv2nv10/UTILS/DOS/FILEVIEW/ASC2COM.ZIP|v2.05}} | ||
| + | * {{Deark}} | ||
| + | |||
| + | Other: | ||
| + | |||
| + | * [https://github.com/jsummers/myfilecmdmagic] - Has brute-force patterns for use with the [[file command]]. | ||
== Sample files == | == Sample files == | ||
| Line 51: | Line 76: | ||
* {{CdTextfiles|cavebbsfiles/tw2002/twplanet.zip|twplanet.zip}} → README.COM | * {{CdTextfiles|cavebbsfiles/tw2002/twplanet.zip|twplanet.zip}} → README.COM | ||
* {{CdTextfiles|pier01/009a/ada301a.zip|ada301a.zip}} → README.COM (Made by v1.25?) | * {{CdTextfiles|pier01/009a/ada301a.zip|ada301a.zip}} → README.COM (Made by v1.25?) | ||
| + | * {{DexvertSamples|document/asc2com}} | ||
Latest revision as of 14:52, 2 December 2024
Asc2Com is a DOS utility that converts a text document to a COM file that, when executed, displays the text in a viewer. It was developed by MorganSoft. It supports a number of different viewing styles and options.
Contents |
[edit] Discussion
The software was originally in the form of a command-line utility named Asc2Com. Later versions include both a menu-driven utility named Asc2Com, and a command-line utility named A2C.
Depending on the version, and the options used when generating the COM file, it may have a feature (Alt-F or Alt-W) to write the text to a disk file. Run the file, and try pressing F1 for help.
[edit] Format details
[edit] Compression scheme
Version 2.00+ has an option to compress the embedded text with LZW. Here are some notes on the compression scheme.
Code size is 9 to 10 bits. Special codes:
| 256 | Unused or unknown. |
| 257 | Increment code size (from 9 to 10). Seek to the next byte boundary. |
| 258 | Stop. |
The first dynamic code is 259. The code table is never cleared.
The Asc2Com documentation includes some very minimal information about its LZW format.
[edit] Identification
Most versions (except the very early ones) offer 5 or 6 different "listers", i.e. templates for the generated COM file, with different feature sets. Files made by a particular version, using a particular lister, have a fairly consistent format, and can readily be identified. But there are many versions of Asc2com (some of which might be lost), and a combinatorial explosion of formats.
Not every version+lister combination represents a unique format, but there are still a few dozen essentially different formats to deal with. So, precisely identifying and analyzing Asc2Com files can take significant effort.
Generated files usually contain one of the following ASCII strings somewhere in them:
- "
Com File Generated by ASC2COM" (Used by older versions.) - "
Com File generated by ASC2COM" - "
File made by ASC2COM"
Known exceptions:
- Compressed v2.01 files contain "
ASC2COM V2.00,COMPRESS". - Compressed v2.05 files contain "
ASC2COM V2.01,COMPRESS".
[edit] Software
Encoding/decoding:
- Asc2Com
- v1.10b (or at Internet Archive)
- v1.25 and v1.25b (no copy found)
- v1.30
- v1.50 (no copy found)
- v1.65 (no copy found)
- v1.66: DISK1948.ZIP → ASC2C166.LZH
- v1.75: Frostbyte's 1980s DOS Shareware Collection → floppyshareware.zip → LUNACY/ASC2C175.ZIP
- v1.76
- v2.00
- v2.00f: a2c20f.exe - Patch to upgrade v2.00 to v2.00f
- v2.01
- v2.05
- Deark
Other:
- [1] - Has brute-force patterns for use with the file command.
[edit] Sample files
- BTX.ZIP → *.COM
- AMORT21.ZIP → *.COM
- TMCAP311.ZIP → *.COM
- FRAMEGRB.ZIP → INFO1.COM
- twplanet.zip → README.COM
- ada301a.zip → README.COM (Made by v1.25?)
- dexvert samples — document/asc2com
