BACKUP (MS-DOS)
| Line 19: | Line 19: | ||
=== Format details - 3.3 === | === Format details - 3.3 === | ||
Just two files are written to each floppy disk: CONTROL.001 (or .002, etc.), and BACKUP.001 (.002, etc.). The CONTROL file contains information about the file data in the corresponding BACKUP file. | Just two files are written to each floppy disk: CONTROL.001 (or .002, etc.), and BACKUP.001 (.002, etc.). The CONTROL file contains information about the file data in the corresponding BACKUP file. | ||
| + | |||
| + | == Identification == | ||
| + | === Identification - 2.0 === | ||
| + | BACKUPID.@@@: (TODO) | ||
| + | |||
| + | Data files: It's possible to heuristically identify these files from their contents, but they don't really have any distinctive markings. (TODO) | ||
| + | |||
| + | === Identification - 3.3 === | ||
| + | A CONTROL.* file starts with byte {{magic|0x8b}}, followed by ASCII "{{magic|BACKUP }}" (which ends with two spaces). | ||
| + | |||
| + | The BACKUP.* files can't be identified from their contents, as they contain nothing other than the contents of the backed up files. | ||
== Specifications == | == Specifications == | ||
| − | * [ | + | * [https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/dos/restore/brtecdoc.htm Tech docs from FreeDOS] |
| − | * One could presumably learn about the | + | * One could presumably learn about at least one of the formats from the MS-DOS 4.0 source code, listed below. |
== Software == | == Software == | ||
| Line 29: | Line 40: | ||
== Sample files == | == Sample files == | ||
| + | 2.0 format: | ||
* {{DexvertSamples|archive/dosBackupFile}} | * {{DexvertSamples|archive/dosBackupFile}} | ||
| + | * [{{DiscMasterURL|browse/30126/07.iso/c/c006}}] → *.ddi ([[DDI|DiskDupe]] format) → ... | ||
| + | ** Examples of split files are LNALLMS.BAT from parts 1 and 2, and BTPARSE.EXE from parts 2 and 3. | ||
| + | |||
| + | 3.3 format: | ||
| + | * {{{CdTextfiles|pcblueii/PCBLUE/VOL583.ZIP|VOL583.ZIP}}, {{CdTextfiles|pcblueii/PCBLUE/VOL584.ZIP|VOL584.ZIP}}} → ... | ||
== Links == | == Links == | ||
Revision as of 17:59, 4 July 2025
The BACKUP command in MS-DOS backed up the contents of a hard disk to files of a proprietary, undocumented format which could be returned to their original file structure using the RESTORE command.
There are at least two quite different formats:
- The format used by MS-DOS 2.0(?) through 3.2. We'll call it 2.0 format.
- The format used by MS-DOS 3.3 through 5.x. We'll call it 3.3 format.
For the format used by MS-DOS 6.x's MSBACKUP.EXE utility, see Norton Backup.
Contents |
Format details
Format details - 2.0
Backed up files usually keep their original filenames. The data is modified, to add a header. In case of a duplicate filename (because the same filename appeared in different directories), a replacement extension like .@02 is used. A file may be split into multiple backup files, each containing a fragment of its data.
An extra BACKUPID.@@@ file is written to each disk, containing general information about the backup. It doesn't contain any critical information.
Format details - 3.3
Just two files are written to each floppy disk: CONTROL.001 (or .002, etc.), and BACKUP.001 (.002, etc.). The CONTROL file contains information about the file data in the corresponding BACKUP file.
Identification
Identification - 2.0
BACKUPID.@@@: (TODO)
Data files: It's possible to heuristically identify these files from their contents, but they don't really have any distinctive markings. (TODO)
Identification - 3.3
A CONTROL.* file starts with byte 0x8b, followed by ASCII "BACKUP " (which ends with two spaces).
The BACKUP.* files can't be identified from their contents, as they contain nothing other than the contents of the backed up files.
Specifications
- Tech docs from FreeDOS
- One could presumably learn about at least one of the formats from the MS-DOS 4.0 source code, listed below.
Software
Sample files
2.0 format:
- dexvert samples — archive/dosBackupFile
- [1] → *.ddi (DiskDupe format) → ...
- Examples of split files are LNALLMS.BAT from parts 1 and 2, and BTPARSE.EXE from parts 2 and 3.
3.3 format:
- {VOL583.ZIP, VOL584.ZIP} → ...
