PC-Shrink
PC-Shrink a compression/archiving utility, and a component of PC-Install. PC-Install is installation software for DOS and Windows, developed by 20/20 Software.
Its file format is .SHR. The format might also be embedded in some self-extracting installer files -- more research is needed.
It uses PKWARE DCL Implode compression.
There are two known versions of SHR format. We'll call them "old" and "new", on the assumption that the one with generally larger segments and fields is newer.
Contents |
File structure
The information here is based on educated guesswork. It was written for the fileformats.archiveteam.org wiki.
An SHR file starts with a fixed-size archive header. Normally, this is followed by a sequence of member files, each with a fixed-size file header. Multi-part archives are different, though -- best guess is that the data after the archive headers needs to be collected and concatenated.
Old format file structure
The archive header size is 56 bytes. Each file header is 48 bytes.
Archive header:
| Offset | Length | Description |
|---|---|---|
| 0 | 13 | Usually all 0x00 bytes. |
| 13 | 1 | Always 0x74. |
| 14 | 2 | Number of member files. |
| 16 | 1 | Always or usually 0x74. |
| 17 | 39 | Usually all 0x00 bytes. |
New format file structure
The archive header size is 58 bytes. Each file header is 168 bytes.
Archive header:
| Offset | Length | Description |
|---|---|---|
| 0 | 14 | All 0x00 bytes for a single part archive. A filename appears here if the file is part of a multi-part archive. |
| 14 | 2 | Always 0x74 0x00. |
| 16 | 2 | Number of member files. |
| 18 | 2 | 0x74 0x00 for a single-part archive, or the initial file of a multi-part archive. 0x75 0x00 for non-initial files. |
| 20 | 38 | Usually all 0x00 bytes. But, for example, the first byte is 0x05 in some self-extracting installers.
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Software
- PC-Shrink (These items have not all been confirmed to use SHR format.)
- PC-Install 4.0 (at Vetusware) (for DOS). Includes SHRINK.EXE (create SHR files), PEEK.EXE (list contents), SPLIT.EXE (make multi-part archive).
- PC-Install 4.00 Pro (at Vetusware)
- PC-Install Super Combo 5.0 (at Vetusware)
- PC Install (at Vetusware) (v6 for Windows?)
- PC-Install with Internet Extensions 6.03 (at Vetusware)
- PC-Install with Internet Extensions 7.0 (at Vetusware)
- Pelit CD-ROM #2 → PCDB.ISO → OHJELMAT/ATRILOGY.ZIP → SHRINK.EXE - A copy of the compression utility from PC-Install 4.0
- dosdemo.zip - PC-Install demo for DOS. Does not demonstrate SHR format. Unknown if it can be made to decompress SRH files.
Sample files
Old format:
New format:
