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Apple disk images that lost their attributes

NeXT

NeXT

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I'm trying to write out a set of Lisa disks and I'm finding that while I am downloading them through Internet Explorer 5 and Netscape directly to a classic mac they are unstuffing from bitsavers as the dreaded "file". The images themselves still work if you fired them over to a Lisa via serial and wrote them using BLU and they are all .image and .dc42 images so they should work with Disk Copy 4.2 but because they don't have a file type attribute, Disk Copy refuses to see them as valid images. I am currently not setup to write every disk out over serial and the only recommended program so far that tweaks attributes (FileType) does not work on 8.1. How can I fix the attribute so I can make Disk Copy work with them?
 
I'm almost positive it can, but I have no clue what it wants me to fill the blanks in with, unless I just need to copy and paste the resources from a good image file?
 
Okay I just went and compared and yes, Disk 1 for LOS 3.1 contains a single resource called dCpy. I can easily recreate or paste that over but this also contains the tag and data checksums. Would those be referenced by the imaging utility to verify integrity or is just so it can display the already calculated checksums?
 
NeXT said:
copy and paste the resources from a good image file?
Click to expand...

Not the resources, just the type (and creator?) attributes. That's what I always do. If there are additional resources with the tag and data checksums, then that may not be sufficient.
 
For Disk Copy 4.2 disk images, all of the data you need to work with the images successfully is in the data fork. You can find all the information you are likely to ever want to know about the format of DiskCopy 4.2 images here:

https://www.discferret.com/wiki/Apple_DiskCopy_4.2

(I can vouch for the quality of this data, which has allowed me to write simple programs that create DC42 files "by hand", like this one.)

Note where it says "Disk Copy 4.2 files have a resource fork, but it only contains a copy of the data and tag checksums and can be safely ignored; files without the fork will still work perfectly." The files from Bitsavers will not have this resource fork data, and that's fine. The data fork has all of the sector data, all of the sector tags, all of the checksums, etc.

As the page shows, Disk Copy 4.2 files have their type field set to dImg (note capital letter I) and their creator field set to dCpy. For the convenience of anyone visiting this thread who's also dealing with these problems, here's a webpage that describes how to set type and creator fields with ResEdit.
 
That was exactly what it was. Switching type to dImg and creator to dCpy instantly made it work under Disk Copy.
 
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