Questions on dumping low density Macintosh disks

[floppydumper]

I'm backing up some old commercial Mac games which are on LD 3.5" disks. Is there any reason to have the drive set to "High Density" for this, or will "Low Density" capture everything needed?

Also, is there a good way to verify my dumps short of just writing them back to disks immediately? I've been using the scan option of Samdisk to verify my dumped PC stuff, but it apparently only supports MFM and FM encoding, so I can't use it for this task (Mac disks are GCR).

Thanks!

[admin]

I have only used low density for imaging Mac disks. I don't know of any programs (other than what I wrote for the Amiga) for verifying Mac disks.

[SomeGuy]

Really, somebody needs to bug the HxC folks about implementing Mac conversion support. However unless I am mistaken, their emulator hardware won't connect to a Mac, so they probably don't care about Mac.

Mac 400k/800k disks are a real headache. Not only are they CGR encoded, and they don't use the index pulse, but they use variable bit rates!

On a real mac, the drive motor spins at a different speed depending on what track it is on. Of course, the SCP copies whatever bit rate it sees.

The following uses the PCE tools to decode a Mac sector image from an SCP file. It outputs a list of sectors and any errors it has found to a text file.

I'm not sure if the following is 100% correct, I only have a couple of mac disks to test with. If you get about one CRC error on each track, then the disk was probably not written index-aligned, and the disk needs to be read using splice mode.

Code:

pfi "Your File Name Here.scp" disk1.pfi

pfi disk1.pfi -c 00-15 -r 380000 -p decode pri diska.pri
pri diska.pri -p auto-align-gcr -p decode gcr diska.psi -f -v

pfi disk1.pfi -c 16-31 -r 350000 -p decode pri diskb.pri
pri diskb.pri -p auto-align-gcr -p decode gcr diskb.psi -f -v

pfi disk1.pfi -c 32-47 -r 315000 -p decode pri diskc.pri
pri diskc.pri -p auto-align-gcr -p decode gcr diskc.psi -f -v

pfi disk1.pfi -c 48-63 -r 285000 -p decode pri diskd.pri
pri diskd.pri -p auto-align-gcr -p decode gcr diskd.psi -f -v

pfi disk1.pfi -c 64-79 -r 255000 -p decode pri diske.pri
pri diske.pri -p auto-align-gcr -p decode gcr diske.psi -f -v

psi diska.psi -m diskb.psi -m diskc.psi -m diskd.psi -m diske.psi disk1.psi
psi disk1.psi disk1.img
psi disk1.psi -L > disk1.txt

erase disk1.pfi
erase disk1.pri
erase diska.pri
erase diskb.pri
erase diskc.pri
erase diskd.pri
erase diske.pri
erase diska.psi
erase diskb.psi
erase diskc.psi
erase diskd.psi
erase diske.psi

[floppydumper]

SomeGuy,

This is fantastically useful. I'm doing PC disks right now, but this will definitely be useful when I get done with those. Thanks a ton!