It's a tool that will scrub your hard disk, bypassing all the built-in mechanisms to repair sectors on the disk. It can fix many a hard disk that would otherwise be toast because of a few bad sectors here and there, and will in most cases help recover files.
(I've personally never seen DynaStat working, but I guess that makes me lucky.)
SpinRite can run on any PC compatible system with a 32 or 64-bit Intel or AMD processor and a color screen. The previous SpinRite v5.0 is available to v6.0 owners who need to run SpinRite on older 16-bit 8086/80286 systems and/or monochrome screens.
SpinRite is self-contained, including its own bootable FreeDOS operating system. It can be used on any operating system and any file system. This means it can run on drives formatted with Windows XP's/Vista's/Windows 7's NTFS and all other older FAT formats (in addition to all Linux, Novell, and all other file systems.) It can be used to pre-qualify and certify unformatted hard drives before their first use. Drives on non-PC platforms, such as Apple Macintosh or TiVo, may be temporarily relocated to a PC motherboard for data recovery, maintenance and repair by SpinRite.
SpinRite provides complete interaction with IDE-interface PATA (parallel ATA) and SATA (Serial ATA) drives, and it can also be used with any other type of drive — SCSI, USB, 1394/Firewire — that can be made visible to DOS through the addition of controller BIOS or add-on DOS drivers. To obtain the best performance, IDE drives can be temporarily removed from their external USB or Firewire cases and attached directly to the PC motherboard.