Technical Features of MacDisk

Summary: Detailled presentation of the technical features of MacDisk, our program to read/write/format Macintosh media on a PC computer and to transfer data and exchange files between Macintosh and PC.


We present below all features of our MacDisk. Please note that some of those features are of a rather technical nature and that you should not be afraid if you don't understand everything. The daily use of the program doesn't imply to know and understand each of them.
See also at the end some comments on the methods used to access physical drives.


For some items, we include links to other pages of this site presenting some explanations if you need them.

Low-level Disk Access

For a long period, we used the Aspi layer to access the physical drives on the computer at the lowest level. This software layer was very convenient. Its success was so big that some conflicts of interests appeared, and it seems that developments ceased.
This happened at the worst moment (as always), while Windows XP (and, before, Windows 2000) was changing its access methods to drives connected to the parallel port, to the USB bus and to the FireWire (IEEE 1394) bus, that is almost all drives with removable media.
We had therefore to ressort to the access methods recommended by Microsoft, that is IOCTL (In/Out Control) and SPTI (SCSI Pass-Through). Those interfaces are fine and allow to do the same work as the ASPI layer, but the low-level access to disks is reserved to user with administrator rights. This is not always the case, of course.
The solution we implemented uses a service (lsdiorw) running in the local system space and executing commands sent by the main application, running in the user space. When running idle (that is, when MacDisk doesn't run), the service doesn't consume any system resource.
See our page on this service for more technical information.

Pierre Duhem (ex-Logiciels & Services Duhem)
3, rue Pierre Haret - F-75009 Paris (France) - Tel. (+33) [0]149 700 455