Mac OS Standard is Not So Standard

External Zip

My Quadra 660AV restoration project was going along smoothly. After much effort, I had a caddy based CD ROM drive that would actually ingest AND eject CD’s, and a floppy drive that would do the same for floppies. I had found and installed a very nice 2 GB hard drive (fast and reasonably quiet too!) and loaded Mac OS 7.6 onto it. Everything was going great – time to load up some applications and put this platform to work.

This was a great idea in practice, but how could I make it happen in reality? Most of the software had come from the wonderful Macintosh Garden site, from which I had downloaded a whole series of files to my current Mac, a Mac OS X Lion based iMac. Somehow, those files needed to make it onto the newly installed 2 GB hard drive on my Quadra 660AV. Ideally, I would just create a shared folder between the two computers and copy the files across, but this won’t work because Mac OS X Lion and Mac OS 7.6 don’t share a common version of the AFP protocol needed to let Chooser link up with my iMac. I could go through a common Windows machine, but that would be just more work than would be worth the hassle.

The answer seemed obvious, hence the picture above. The Quadra supports external SCSI, and I just happened to have both an external SCSI ZIP 250 drive and an external USB ZIP 250 drive. Problem solved!

…not so fast. Mac OS 7.6 only understands Mac OS Standard format (Mac OS Extended format hadn’t been invented yet), so I used it to format a Zip 250 cartridge as Mac OS Standard. I popped it in to my USB Zip 250 and my iMac happily mounted it on the desktop and allowed me to view the (empty) contents. It would happily let me READ the contents of the Zip disk, but it would NOT let me WRITE anything to it at all!

It turns out that Mac OS Standard is not quite so Standard any more. In fact, as I discovered after much Google’ing around, Mac OS X Leopard was the last version of Mac OS X to support writing onto Mac OS Standard disks. Happily, my trust PowerMac G5 2.3 GHz Dual Core machine is still running the Mac OS X Tiger that it came with, and I was able to use the network to copy all the software I was planning to install on the Quadra over to the PowerMac G5, and then from there write it onto the Mac OS Standard formatted Zip 250 disk.

So, just a word of wisdom. If you need to write onto Zip disks for consumption on Quadra class machines (or any machine running any version of Mac OS prior to 8.1, which introduced HFS Plus), make sure you have access to a version of Mac OS X up to or earlier than Leopard. As the title implies, Mac OS Standard is not standard equipment any more.

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