Old Schoold by Harri Kauhanen

Creating 400k or 800k Macintosh floppy disks

Macintosh
Storage mediaEmulationDisk copy

If grasping the Macintosh file formats for emulations is challenging, creating diskettes for old Macintosh models is really tricky. The main reason is that old Macintosh models only read so-called 400k or 800k disks, and the sectors in these disks are organized differently from the most other systems (such as MS-DOS). Reading a 400k or 800k disk requires variable rotating speeds from floppy driver controller (and it hears if you listen to the vibrations your Macintosh floppy makes). My method utilizes the fantastic BMOW Floppy Emu that allows me to move files to my Macintosh Plus from SD memory card.

The first step is to create a floppy image that we can open in BMOW Floppy Emu. To make such image is not completely trivial, because HFS file system is no longer supported. It’s possible to create HFS files system with tools like HFSExplorer and HFS Disk Maker. The easiest way is probably to use blank disk images and a Macintosh emulator with a particular software for transferring files.

Assuming you have a .sit file containing a piece of software, the process is:

  • Boot Mini vMac with unarchiver tools you need. You could e.g. use this bootable hard disk containing StuffIt.
  • Import .sit file with ImportFI
  • Mount an empty disk image to Mini vMac (Download or create blank disks).
  • Extract the files and copy them to the empty disk image.
  • Rename appropriately (e.g. from 800K.dsk to My Cool Game.dsk)

Alternatively, you could skip the last three steps, and simply extract .sit to a hard disk image you use with an emulator or BMOW floppy emu (yes, it support hard disk images, too).

The next step is to move the My Cool Game.dsk to an SD card, pluck it into Floppy Emu and boot the real Macintosh. Then just copy the files from emulated floppy image to a real floppy disk.

It might be a good idea make the game disk bootable. If you boot from one disk and run the game from another, you might end up to a disk switching hell before the game is actually playable. So, if you are lucky, and there’s enough disk space for operating system files to live on the game disk, the loading experience will be much smoother. Some ideas:

  • What is the oldest OS version game works on? For instance, System 2.1 takes much less disk space than 5.0
  • Was the game originally distributed on non-bootable 400k disk? Use 800k disk image instead of 400k, and you are likely to fit in an OS.
  • Take a floppy with the operating system of your choice.
  • Try removing the unnecessary system files. You basically need to have System and Finder files, but the rest can usually go.
  • Copy the game files to the floppy.
  • Optionally, select the game executable, and choose Special + Set Startup from the drop-down menus.