SCRNCH
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SCRNCH is fundamentally a [[DOS executable (.com)|COM]] file compressor, but it includes tools that make it possible to compress [[MS-DOS EXE|EXE]] files, using a convoluted method of converting them to a COM or COM-like format that SCRNCH can compress, then back to EXE if necessary. | SCRNCH is fundamentally a [[DOS executable (.com)|COM]] file compressor, but it includes tools that make it possible to compress [[MS-DOS EXE|EXE]] files, using a convoluted method of converting them to a COM or COM-like format that SCRNCH can compress, then back to EXE if necessary. | ||
− | SCRNCH also has a | + | SCRNCH's default COM-to-COM compression mode is called "Run Mode". It also has a mode it calls "Write Mode", which essentially creates self-decompressing files. In the simplest case, Write Mode converts a text file to a COM file that, when executed, prints the text to the screen. With effort, it can be used for other things, like software installation. |
== Identification == | == Identification == | ||
− | + | (Based on limited testing.) | |
+ | |||
+ | SCRNCH v1.00-compressed COM files (both modes) start with bytes {{magic|bb ff ff b4 4a cd 21 81 eb}}. | ||
+ | |||
+ | SCRNCH v1.02-compressed COM files, Run Mode, start with bytes {{magic|eb 13 's' 'C' 'e' 'f'}}. | ||
+ | |||
+ | SCRNCH v1.02-compressed COM files, Write Mode, start with bytes {{magic|eb 13 's' 'C' 'w' 'f'}}. | ||
+ | |||
+ | SCRNCH v1.02-compressed COM files, both modes, also have {{magic|bb ff ff b4 4a cd 21 81 eb}} at offset 21. | ||
== Related formats == | == Related formats == |
Revision as of 18:07, 10 October 2021
SCRNCH is an executable compression utility for DOS. It was developed by Graeme W. McRae, and distributed as shareware.
Contents |
Discussion
SCRNCH is fundamentally a COM file compressor, but it includes tools that make it possible to compress EXE files, using a convoluted method of converting them to a COM or COM-like format that SCRNCH can compress, then back to EXE if necessary.
SCRNCH's default COM-to-COM compression mode is called "Run Mode". It also has a mode it calls "Write Mode", which essentially creates self-decompressing files. In the simplest case, Write Mode converts a text file to a COM file that, when executed, prints the text to the screen. With effort, it can be used for other things, like software installation.
Identification
(Based on limited testing.)
SCRNCH v1.00-compressed COM files (both modes) start with bytes bb ff ff b4 4a cd 21 81 eb
.
SCRNCH v1.02-compressed COM files, Run Mode, start with bytes eb 13 's' 'C' 'e' 'f'
.
SCRNCH v1.02-compressed COM files, Write Mode, start with bytes eb 13 's' 'C' 'w' 'f'
.
SCRNCH v1.02-compressed COM files, both modes, also have bb ff ff b4 4a cd 21 81 eb
at offset 21.
Related formats
Software
- SCRNCH v1.00 (1988-01-31)
- SCRNCH v1.02 (1988-03-28 / 1988-04-04)
- DeSCRE2B - Utility to help decompress SCRNCHed EXE files