Mac 400K/800K 3.5" low-density disks are an unusual format because they use GCR like an Apple II, do not require an index pulse, have different numbers of sectors per track, and use variable bit rates depending on the track.
For this I used the PCE Tools located here: http://www.hampa.ch/pub/pce/pre/pce-201 ... -win32.zip
and HxC located here: http://hxc2001.com/download/floppy_driv ... t_beta.zip
Basically, the PCE Tools (PSI, PRI, PFI) should be able to do the conversion itself, but it currently has some bugs, or I'm doing something wrong that I haven't figured out yet.
First, start with a sector image of an 800K Mac disk in DiskCopy 4.2 format. At the moment, raw images will need to be converted to DiskCopy 4.2. There should be some tools out there that can do this, but I couldn't find any off hand. According the the change logs, the next release of the PCE tools should support a "MAC" raw sector image type in addtion to "DC42", so conversion should not be needed. Just slapping a header on won't work because it checks the file CRC against that recored in the header.
With the DC42 image named "test" do:
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psi test.dc42 disk1.psi pri -p encode gcr disk1.psi disk1.pri -f -v pfi -p encode pri disk1.pri disk1.pfi pfi disk1.pfi track00.0.raw
So next, open the file in the HxC disk tool and re-save it as a Kryoflux image. Note that the HxC tool does not know how to decode Mac 400K/800k variable bit rate disks, but it will convert the stream file anyway.
THIS stream file can now be written to a floppy disk, although it seems to still have some invalid RPM info.
I tested writing an 800K image to a double density disk and it was readable on a Power Mac. It is possible that the low-level format written has some issues, but it is readable.
Tracks Sectors RPM Clock/KBps
00-15 12 393.3807 381310
16-31 11 429.1723 349510
32-47 10 472.1435 317700
48-63 9 524.5672 285950
64-79 8 590.1098 254190
The Macintosh implements the variable bit rate by spinning the drive motor at different speeds while writing the same data rate at the head.
The Central Point Deluxe Option board implements the variable bit rate by controlling the rate in its digital hardware.
The Kryoflux implements variable bit rate decoding in software. (does not support encoding sector images).
The PCE tools create the stream file as if it were read in a Mac drive with variable RPM. It does this because the PCE emulator simulates a Macintosh drive at a closely accurate hardware level. This is unlike images of real Mac disks read by the Kryoflux, which will always have 300RPM on all tracks.
Kyroflux must write this to a PC drive at constant RPM by varying the write data bit rate. Additionally PC 720K/1.44mb drives are not really designed for anything other than 250Kbps on low-density disks - but it seems to work well enough.
Also, the Apple Lisa 3.5" disk format use extra sector tags, however Apple II Prodos/GSOS 3.5" disks and Macintosh disks do not. This means Lisa images can not be stored as raw sector images, only Mac DiskCopy 4.2 images.