README

dd

A version of dd, usable in earlier versions of Windows. Based on the original version by John Newbigin, with some of my (Dmitry Brant) own tweaks, as I need them.

Build instructions

• Get a virtual machine going with a clean install of Windows 2000.
• Install Borland Delphi 7 (available on the web).
• In Delphi, select File -> Open Project, and open dd.dpr.

Random use cases

SyQuest SparQ

I needed to recover data from some SyQuest SparQ cartridges, and the SparQ drive (which connects to the parallel port) has drivers that work only with Windows NT and earlier (no support for Linux, of course). Getting the driver installed was actually pretty simple, and it provides an emulated "SCSI" interface that lets Windows access the drive at the block level, i.e. it becomes a standard removable disk. Therefore it should be possible to use a tool like dd to read all the data from it.

With my modifications to this tool, it will attempt to retry reading bad sectors, which can actually result in a successful read after several attempts, similar to "SpinRite" logic. (There doesn't seem to be any caching at the level of the driver or the device, so retrying a read will definitely retry it physically.) And if a read is definitely unsuccessful, it can skip and go to the next sector, while padding the bad sector with zeros, mirroring the behavior of conv=sync,noerror.