Writing 1.44MB floppies for SE/30 on OS Mojave 10.14.4

[ryan9699]

Hi everyone,

I recently got my hands on an old SE/30 and I'm trying to write some System 7.0.1 compatible programs on floppy disks. I'm fairly new to this stuff, so bear with me.

I have an external floppy drive, which I know works, because I can read floppies that are formatted by my SE/30. Only thing is, I can't write to them. I can only write to them if I first unmount the floppy (which nulls the formatting that is done on my SE/30). I'm getting successful results using the terminal command " sudo dd bs=84 skip=1 if=MacWrite.dmg of=/dev/disk2 ", but only after I've used " diskutil unmount /dev/disk2 ".

I know that the programs I'm writing are compatible, because I'm using the disk images on mini vMac, and they all run successfully. However, my main focus here is that I'm trying to avoid having to unmount the floppy, because using intuition, I think that it de-formats the disk, making the floppy unusable with the SE/30. I've loaded the floppies into the SE/30, only to be prompted with the typical "eject/initialize" message. 

Can anyone offer some guidance as to what I should be doing, or where I should go from here? Thanks.

Ryan

 

[pcamen]

A modern Mac can’t write at all to an HFS formatted disk.  When you write with the dd  command you are not writing HFS you are just sector by sector writing an HFS image.  The dd  command doesn’t know anything about the format of the disk, it just sees bytes.  For that, overwriting the entire disk, it can’t be mounted because you are replacing the entire disk contents.

i know I saw someone mention on another thread leaving part of the above dd command out to get it to work.  I think it is the skip=1 part; I think that is only for creating an image from a floppy.  You might try that.

 

[NECyclone]

You don't happen to have Windows on your Mac with bootcamp?  Or Windows running under something like Parallels on your Mac.  I say this cause I had your same problem but now use the program Macdrrive under Windows and its worked quite well for me.

 

[pcamen]

From Low End Mac 

http://lowendmac.com/2007/making-floppies-and-cds-for-older-macs-using-modern-macs-windows-and-linux-pc

see the section on Linux for the dd stuff.  It might be that you have a raw image not a DC42 one.

 

[ryan9699]

Update: was able to get it to work by dismounting the floppy in DiskUtility (not in the terminal window using diskutil unmount, for some reason this never worked) and by typing in:

MacBook-Pro:~ name$ sudo dd if=filenamehere of=devicename bs=84 skip=1

to Terminal.

Not sure why it works for some people and not for others but... if anyone comes across this thread and needs help with this, it's a place to start. Thanks guys