Weak sector data: Difference between revisions
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Some copy protections have what is described as “weak”, “random” or “floated” data. | |||
Each time the “weak” sector is read one or more bytes will change. Their value | |||
Each | |||
may be random between consecutive reads of the same sector. | may be random between consecutive reads of the same sector. | ||
Weak data recorded | Weak data can only be recorded using modified hardware, so you cannot easily copy these disks. | ||
Only | Only the [[DSK format|Extended DSK]] and [[UDI format#UDI: Ultra Disk Image file format Version 1.1|UDI 1.1]] disk image formats record this type of data. | ||
== Copy protection == | == Copy protection == | ||
Weak sectors used by [[Speedlock]] copy protection | Weak sectors are used by the [[Speedlock]] family of copy protection routines for [[ZX Spectrum +3]] disks. | ||
Usually weak sector data combined with other | Usually weak sector data is combined with other techniques for disk copy protection, such as: | ||
* different sector | * different sector lengths for different tracks | ||
* different sector | * different sector lengths within a track | ||
* sectors marked as deleted | * sectors marked as deleted | ||
* sectors with CRC error | * sectors with CRC error | ||
* | * incorrect sector header information e.g.: | ||
** track number | ** incorrect track number | ||
** | ** increased sector length | ||
== Disk images with weak sectors == | == Disk images with weak sectors == | ||
Unfortunately, disk images with | Unfortunately, disk images with the weak sector data recorded are rare, so if a program reads the same sector repeatedly then some emulators assume that this sector has weak data. (which emulators?) | ||
Revision as of 19:55, 21 February 2016
Some copy protections have what is described as “weak”, “random” or “floated” data.
Each time the “weak” sector is read one or more bytes will change. Their value may be random between consecutive reads of the same sector.
Weak data can only be recorded using modified hardware, so you cannot easily copy these disks.
Only the Extended DSK and UDI 1.1 disk image formats record this type of data.
Copy protection
Weak sectors are used by the Speedlock family of copy protection routines for ZX Spectrum +3 disks.
Usually weak sector data is combined with other techniques for disk copy protection, such as:
- different sector lengths for different tracks
- different sector lengths within a track
- sectors marked as deleted
- sectors with CRC error
- incorrect sector header information e.g.:
- incorrect track number
- increased sector length
Disk images with weak sectors
Unfortunately, disk images with the weak sector data recorded are rare, so if a program reads the same sector repeatedly then some emulators assume that this sector has weak data. (which emulators?)