View Full Version : Calling all cross-platform wizzkids!

10-23-2003, 02:01 AM
Hi everyone. I have a problem I need help to solve. I shall try to explain as best I can.

I work mainly on a mac for design work, and then convert the results into DXF for Vector to import on the PC.
I recently have been having problems with the Mac Hard disc. I decided to reformat.

I managed to transfer all my programs and data as follows.

First from the mac into a 100mb Zip, then, via a PC, to a cd.

I used AHEAD software with a drag and drop cd writer.

It took all day, but finally I "Saved" all the software, and reformatted the mac's hard disc.

Now when I come to reload the software, The mac doesnt recognise anything as an application, instead it seems to see everything as a document requiring a program to run it. There are literally dozens of small shareware and freeware programs I have downloaded from the web over the years which I use all the time to make my life easier, and they all come up with a blank icon and cannot open. Most of them are now irreplaceable.

Obviously the process of saving on the CD has changed them in some way, stripped them of some vital bit of code that tells the mac how to treat them.

They all appear to have the same size as before, and their names have not changed in any way.

Does anyone know what to do?

10-23-2003, 04:16 AM
Each file on a Macintosh has two forks: a resource fork and a data fork. The resource fork holds things like icons and string tables and code resources. Your CD writer on the PC did not save the resource fork. When you transfer a Macintosh file to a PC, you will probably lose the resource fork. That is generally true. It is possible to write a CD in Mac format. Your CD writer on your PC was probably set to write in ISO9660 or Joliet format. The best way to transfer files from a Macintosh to a PC is to compress everything into an archive file first on the Macintosh because that will save both the resource and data forks in the archive. If you had done that, you would have been able to transfer the archive from the Mac to the PC and then back to the Macintosh, uncompress it, and everything would have been fine. Since you didn't do that, you lost the resource forks. The Macintosh programs that you transferred will be unusable, and you'll have to install them again from the CD or download them again. However, you should be able to open data files from the program which created them. You won't be able to double-click on the data files to start the program, because you have lost the resource fork to those files. If you launch the Mac program first, and then open the data file from within the program and then save the file, that should restore the resource fork for that data file. It is possible to repair individual data files by opening them in ResEdit or Resorcerer and then setting their TYPE attributes to the program which created them. After that, it should be possible to double click on the data files to open them (if you have the program installed). Sorry for your loss.

10-23-2003, 05:04 AM
Hi Simon,

Assuming you had irreplaceable data/applications, I would try to salvage the data with data recovery software like VirtualLab (http://www.binarybiz.com/vlab/mac.php) - essentially unformatting your disk. Then do what Mike said- compress the data with something like StuffIt (Sit), then burn it on the PC. Format Mac drive, install UnStuffit, & restore the data with UnSit.

If you've written new data to the disk, those sectors may not be recoverable/unformattable.

If the cross platform stuff is getting old, or your tired of finding that apps you want won't work on a Mac, you may want to try Virtual PC for Mac (http://www.microsoft.com/mac/products/virtualpc/virtualpc.aspx?pid=virtualpc). At work, we were shocked to see some apps that we wrote for the PC worked fine on a Mac using this software. Supposedly, it also allows you to use cross platform files directly without conversions.


10-23-2003, 04:20 PM
Hi Mike and John

Thanks for your input. The problem seems to have solved itself by reversing the process, copying onto a zip first, and then back into the mac. The zip seems to reconstruct the applications in the way they were intended.
I noticed that while copying onto the PC, some strange files appeared called resource fork, which were invisible on the mac. Thanks to Mike I now understand what they were.


10-23-2003, 04:47 PM
Great. For a good historical explanation of Mac resource and data forks, click here (http://mail.gnu.org/archive/html/help-cfengine/2003-08/msg00059.html)