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Write HFS floppy with MacOS Sierra or lower

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Year released:
[www].se [ftp].se [mirror].us (270.14 MB)
MD5: 408c4bfe361d92a866872fce9f2acec5
[www].se [ftp].se [mirror].us
This app works with: Mini vMac

Its a known fact, that OS X can not write HFS Standard floppies as of 10.6 and higher.
However there is the dd command available in all *nix systems.
Unix guys will know. For the others, dd and Terminal can do many useful things, including writing to HFS floppies.

What is needed:

Mac OS X 10.12 or lower.
Terminal App from Application/Utilities
USB floppy drive.
Installation of Mini vMac_II with Mac OS 7.5
RAW floppy image
Transport dmg, DOS formatted.
(The last three are included in the DL file.)

Lets assume you want to write the game file MacYahtzee to floppy with your Mac running Sierra.

Its impossible to write to a HFS Standard volume from userland with any recent flavour of OS X.
We may write to DOS volumes though and Mac OS 7.5 does read those volumes too.
Double click the Transport.dmg and copy the downloaded mac_yahtzee.sit to it which we are using as an example here.

Step 1

Drag Transport.dmg into your Sierra dustbin when done. (this is important!)

Double click Mini vMac and drag MacII_HD75 onto it as the screen with the blinking question mark appears.
Next drag Transport.dmg onto Mini vMac´s screen to mount it.

Step 2

Open Transport.dmg, copy the sit file to the TEMP folder and drag and drop the sit onto the StuffIt Expander alias.
Unmount Transport.dmg by dragging it into the Mini vMac dustbin when done.

Step 3

Copy the 1440.dsk file from the DL to the root directory of your boot volume.
Your user pass will be needed to do so with Sierra.

Step 4

The dd command seems to be picky when writing files to floppy,
so you do use the untouched 1440 RAW image from the DL.
Drag the 1440.dsk onto the Mini vMac screen and copy the MacYahtzee app to it.
Shut down Mini vMac when you are done.

Step 5

Insert a floppy and open DiskUtility. Use the Info button to find out the device ID of your floppy. For this example, lets assume the floppy is disk3.
Now select Unmount.

Open Terminal and type in (or copy/paste):
sudo dd if=/1440.dsk of=/dev/disk3

Step 6

Because of sudo, you will have to type in your OS X password.
The copy process will need some time. The whole floppy is written.
As you got a similar output as the above picture, use DiskUtility to mount/unmount the floppy to see it in Finder.

Step 7

Done. Your files should show up in the floppy!

Now eject 1440 and take it to your vintage Mac.

Have fun!

Many thanks to all those tinkering with dd, especially to Max1zzz for pointing to RAW and Mini vMac!

At last a warning to the casual reader:
Though very little can go wrong, if you follow the above to the letter, it is jokingly said that dd stands for "destroy disk" or "delete data", since when used for low-level operations on hard disks, a small mistake such as reversing the input file and output file parameters could result in the loss of some or all data on a disk.
m m )

Edit: I don't have a suitable Mac any more to read the floppy created above.
Basilisk II build 142 for Windows does read HFS floppies though, this is how it looks:

All done.


OSX X86 and X64


MikeTomTom's picture
by MikeTomTom - 2017, January 20 - 2:38am

something seems to have been broken.

... I was able to edit it OK, after your previous edit.

24bit's picture
by 24bit - 2017, January 19 - 10:41pm

Thanks for your time Mike, the procedure looks good now.

I tried to fix some typos of mine, but something seems to have been broken.
I´m not going to touch the guide miracle again!

MikeTomTom's picture
by MikeTomTom - 2017, January 19 - 10:00pm

Easy. Made sticky too Smile

24bit's picture
by 24bit - 2017, January 19 - 3:27pm

An admin could add the pictures in the text file eventually? Wink
Or maybe move the whole thing to the guides section?

The floppy procedure itself is dead simple, but Apple´s security scheme is always throwing sticks between one´s legs. Cant be a big issue to leave write access to HFS Standard enabled if they would choose to do so.

IIGS_User's picture
by IIGS_User - 2017, January 19 - 9:07am

Thank you very much for pointing out. Smile