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(Created page with "= Weak disk data = 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, the v...") |
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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 | |||
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 [[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 == | |||
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. (e.g. [[Emulators#Fuse|Fuse]]) |
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