OSDev.org

Posted: **Wed Jan 07, 2015 5:36 pm**

I'm trying to get my environment set up for OS X. My coding was all done in Windows before, so now I'm working on getting scripts in order to make a floppy disk image out of my assembled sources.

Part of my little shell script looks like this

Code: Select all

    #Format image in MSDOS format and mount it
    DISKNAME=`hdiutil attach -nomount bos.img`
    diskutil eraseVolume MS-DOS BOS $DISKNAME

This all works fine... Except. It uses what I suspect is HDD like values for the FAT12 BPB.

/dev/rdisk1: 2829 sectors in 2829 FAT12 clusters (512 bytes/cluster)
bps=512 spc=1 res=1 nft=2 rde=512 sec=2880 mid=0xf0 spf=9 spt=32 hds=16 hid=0 drv=0x00

So..
RDE (root directory size) of 512 instead of standard floppy 224
SPT(sectors per track) 32 instead of standard 18.
HDS(heads) 16 instead of standard 2

Is there something I can do for diskutil to treat this as a floppy and not harddrive? Or any other tips for working with floppy images under OS X?

Posted: **Thu Jan 08, 2015 1:13 am**

I would always recommend mtools for being an OS-independent tool for do the job. I'm also guessing that (knowing Apple) getting access to a mac and personally reading the documentation is going to be little more than duplicated effort.

Posted: **Thu Jan 08, 2015 10:42 am**

While I would prefer to do this with built in tools, I can understand if it's not possible. I've already tried mkdosfs-osx package which didn't work out well, but "mtools" was news to me. Homebrew could fetch it without problems, and mformat seems to do excatly what I need. Thank you!

Posted: **Sun Jan 25, 2015 9:22 pm**

bubach wrote:While I would prefer to do this with built in tools, I can understand if it's not possible. I've already tried mkdosfs-osx package which didn't work out well, but "mtools" was news to me. Homebrew could fetch it without problems, and mformat seems to do excatly what I need. Thank you!

Okay, forgive me if I am thinking a bit too much like Linux but here we go: If I am correct there should be a shell command called mkfs.fat. It works like mkfs.fat [device/file] [sectors], now be careful because it is kind of like dd. It will overwrite everything on the drive. If you are writing it to a file then make sure to specify sector size or it could fill your hard drive.

According to MikeOS it creates a FAT12 system. The exact command used was:

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mkdosfs disk_images/mikeos.flp 1440

I might be off with the directory structure, but it still works. Hope I helped!

OSDev.org

Formatting fat12 floppy image in OS X

Formatting fat12 floppy image in OS X

Re: Formatting fat12 floppy image in OS X

Re: Formatting fat12 floppy image in OS X

Re: Formatting fat12 floppy image in OS X