Can't PC floppy drives write double density? You'd think they could, having been encumbered with a compulsion for backwards-compatibility ever since RISC processors came out. (Not that I'm the one to talk, whining about Apple dropping AppleTalk from 10.4 to 10.5 and PPC in 10.6)

Click to expand...

PC drives can read and write double density, but they use a different scheme to deal with data on floppies. Macintoshes use GCR (Group Code Recording) while DOS/Windows uses MFM (Modified Frequency Modulation). This is why Apple created the Apple File Exchange or PC Exchange file extension for System 6 and 7. GCR and MFM are two totally different schemes and they don't understand one another.

One thing you can do is use a Windows program like TransMac to put the contents within Apple/Mac disk images onto DOS/Windows floppy disks. This is useful when getting disk images of System 6 or 7 onto multiple floppies to boot up your Mac.

Another way would require you to have a more modern Mac (mid-1990s model, like a Power Macintosh 7500 or 6400, for example) that is Internet ready, download the disk images onto that machine, create the System 6 or 7 floppies there and then use those disks to boot a much older Mac. If you need 800K floppies, but all you have are lots of 1.44MB disks, you can turn them into 800K disks simply by placing a piece of scotch tape or masking tape over one of the holes. You'll want to place the tape over the hole that doesn't write protect the disk. Once you've taped the disks, place each one into the modern Mac's floppy drive and erase the disk. The Mac will assume they are 400K or 800K disks and ask you which one you want to format as. Choose 800K and you'll be all set.

You could also try a zip drive, if you can find a cheap one for both the Mac (SCSI) and the PC (how did they connect zip drives back in the day?), handy storage instead of having to keep track of a stack of DD floppies. But if you can't find these items for cheap, get a second old Mac, one with Ethernet and a SuperDrive to use as a compatibility layer (though you can use it for all kinds of fun stuff).

Click to expand...

The problem with using a zip drive is 2-fold. First, on most retro Macs, you need to have the Iomega driver version 4.2 or greater installed before using the disks. This means your retro Mac must be already running System 6 or 7 and have the driver installed along with the drive already connected. Second, and this is the double-edged sword, if you avoid the driver, you'd still have to have the retro Mac boot off of the hard drive and stick the zip disk in the drive at the "Welcome to Macintosh" message. This means basically you can't boot from the Zip disk into System 6 or 7.

A third problem is that when dealing with zip disks used on DOS/Windows and Mac, they use also different disk partition schemes; DOS/Windows uses FAT or FAT16, while Mac uses HFS or HFS+ (Extended). They are also not recognized when you go cross-platform, unless the Mac has Apple File Exchange installed.

Interceptor2, if you need a set of floppies made, send me a PM and I'll try to help out.

73s de Phreakout. :rambo: