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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. (e.g. [[Emulators#Fuse|Fuse]]) | ||
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