ISO-no-HFS: an application to mount the ISO 9660 partition of an hybrid CD
What it does:
Well, it happened in spring 1995: I bought a magazine (the Italian version of CD-ROM today) including a CD. An article in the magazine explained that the disk contained both Mac and PC stuff, but I could see only the Mac stuff. Two partitions ? A quick check: sector 0 contained an Apple-like header and sector 64 contained an ISO 9660 header. So, the PC looks at sector 64 and mounts the ISO 9660 partition. The Mac sees a valid sector 0, mounts the HFS partition and does not explore further.
OK, maybe I'm paranoic. I don't like to own a thing and not being able to use all of it. The PC partition should contain only things useful to PC owners, but why should it be forbidden to look at it, on a machine which can mount a PC disk in ISO 9660 format? I'm being robbed of something I've the right to own.
So, I'we written this little application: when it's running, it cheats the Mac so that reading sectors 0 to 15 of the CD yields incorrect results (obviously, any other device is not affected). So, the Mac believes that this disk has no HFS partitions and continues its explorations, that is it looks at sector 64 and… wow! it mounts the ISO partition. Now, the application simply quits, and everything is restored to its normal state: eject the disk and insert it back, and the Mac partition is regularly mounted.
NOTE: having SoftWindows running does not change the rules: the HFS partition has still the precedence over the PC partition. But if you launch ISOnoHFS, insert the hybrid CD and then switch to SoftWindows, you'll be able to work on the CD as you would have done on a PC.
Version 2 is now compatible with SCSI manager 4.3: I've discovered that now there are 4 ways to read sector 0, and version 1 was blocking only one. Now it should work on all Macs running any software, at least until Copland arrives: according to what I've heard, Copland will change all rules about accessing devices.
Disclaimer
This has been my first experience of patching a trap (a technical term… it's the way all extensions use to modify the behaviour of the Mac) and I hope everything is OK. Anyway, an application causes fewer risks of incompatibility than an extension.
In any case, I take no responsibility for any damage or data loss which may be caused by this program.
There is a known incompatibilty: it does not work with AccessPC, which does not like to be cheated and causes a -36 error, so the Mac stops examining the disk and does not continue its search of a valid header. I had no problems with PC Exchange.
I've done this in 68000 code, but since speed is not important it's just as good on a PowerMac: in fact, I've tested version 2 on an 8100.
Copyright notice
This is freeware. You may give it away, and you may send to any BBS or ftp-able archive in Internet and may put it in shareware collections on floppy disks or CD-ROM, provided that this documentation goes with it.
Probably producers of hybrid CDs should want to include it on their products: it's only a few Kbytes and may give some extra value to the CD for Mac users.
If somebody wants, probably he may get the source, there is nothing special in it.
I've written it taking some code from previous works of mine ("1430k free", "SCSI Eject" and "suntar"): probably part of this code contains some contribution by my brother Sauro.
In case you want to contact me, this is my brother's Internet address:
