other specialized software. SpinRite is claimed by its developer to have certain unique features, such as disabling of disk write caching, disabling of auto-relocation, compatibility with disk compression, identification of the "data-to-flux-reversal encoder-decoder" used in a drive, and separate testing of buffered and unbuffered disk read performance. Another important feature is direct hardware-level access, whereby the drive's internal controller interacts directly with the program, rather than through the operating system. This, in turn, allows dynamic head repositioning, whereby, when reading a faulty sector, the reading head is deliberately moved backwards and forwards many times, by varying amounts, in the hope that each time it returns to the sector, it may come to rest in a slightly different position. By performing statistical analysis on the succession of results thus obtained, SpinRite is, according to its maker, often able to "reconstruct" data from damaged sectors, and even in those cases in which complete reconstruction proves impossible, SpinRite is able to extract all intact bits from a partially damaged sector, and to copy them to a new block, thereby minimizing the amount of data lost. Some claims by SpinRite's author have proved controversial. The ability to "refresh" aging drives has been met with particular skepticism while the "recovery" of sectors marked as "damaged" is considered by some to be undesirable and counter-productive. SpinRite is written in x86 assembly language, and runs on any PC-compatible computer, regardless of the operating system installed. It can operate on any attached storage device with a compatible interface. Drives in computers with incompatible processors can be tested by attaching the drive to a compatible computer. Spinrite is distributed as a Microsoft Windows executable program which can create a bootable drive containing both the FreeDOS MS-DOS-compatible operating system and the Spinrite program itself. Version 6 is compatible with hard disks containing any logical volume management or file system such as FAT16 or 32, NTFS, Ext3 as well as other Linux file systems, HFS+ For Mac OS X, TiVo and others. Version 6 offers full access to the entire disk surface regardless of partitioning, Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) parameters and control of partial scanning within a specified percentage range. Version 5 was limited to AT Attachment (PATA, IDE) hard drives; version 6 may, on suitable motherboards, work on newer Serial ATA (SATA) and USB hard drives, and with any other type of drive—SCSI, 1394/FireWire—that can be made visible