Best way to backup Amiga floppies

[sky76]

Hello everyone,

what is the best way to preserve (and make duplicates of) original Amiga floppy disks?

I have about 70-100 (need to count them one day) of original 880KB Amiga floppy disks and I'd like to make backup copies in order to
* use the copied versions for occasional gaming
* spare the original ones and
* have peace of mind knowing my disks are well preserved for eternity.

So I've found out that there are two formats related to Amiga. There is the *AmigaDOS sector image (ADF)* but how does this one deal with copy protection like long tracks or weak bits and stuff? Is it basically the same as doing a TransADF on an original Amiga or X-Copy-ing the disks?

And there is the *Amiga DiskSpare image* format - what is this? Never heard of before.

I've studied the documentation, but there is no real advice on when exactly to use this.

Greetings from Austria and thanks to Christian & Istvan for making this all possible!

[mr.vince]

Hi there, ADF is good for dos disks, nothing else. Some games, especially later ones, had no on-disk protection, so ADF is fine. For the rest, you need some format that can store anomalies if you want to be _safe_.

If you got a KF, you can look for the IPFs (several contributors have made them available online), or you could save to stream and write stream back to disk. Please note this only works _reliable_ if the disk is index aligned.

Cheers!

[sky76]

Hi! Thanks for your reply. Yes, I have a KF (ordered it 2 weeks ago I think).

So I guess there is no difference between an ADF generated with transadf on my Amiga and an ADF generated by Kryoflux (except that different floppy drives may generate slightly different magnetic particles on disks which could result in different stream files when I'd kryoflux them later, but the indexed ADF should always be the same - under the condition that there are no read errors (and no such thing as "repaired checksums" like DOSCOPY+ in X-Copy does) involved)?

[IFW]

KF will never attempt to er... "fix" your disk by reporting no errors when there are errors
DTC is also more strict than most software - it not only checks the checksums, but also the encoding and timing. If any of those fails it will report bad data, while most other software wouldn't (or actually couldn't since timing data is only available with the flux level samples).
I still wouldn't say it's 100% due to the poor parity used by ADOS based formats, but still better than what you get from the original OS, which is purely checksum based.

So in theory there is no difference is practice it's more likely to be good if the KF software does not complain
I'd also like to highlight that Christian talked strictly about writing stream files back to disk fully reliable only (at the moment) for index synced disks.
If you write back IPF files it does not matter whether the data requires index syncing or any specific start on a track - it will be replicated perfectly.

[IFW]

DiskSpare was a format used by an Amiga magazine to publish their cover disks; it was also available as device library for users to access the disks from AmigaDOS I think. It has a slightly higher capacity than normal ADOS.

[sky76]

Thank you for the good explanation. In the meantime I've dumped several protected Amiga NDOS disks with different floppy drives and only recently I started to write stream files back to disk to see whether they'd run on a real Amiga - and they did.

I used the following command:

Code: Select all

dtc -fGemX/track -w -wi4 -k1

I think the "-k1" Parameter (track distance = 80) is mandatory for Amiga disks.

[Sirswift89]

Thank you for the good explanation. In the meantime I've dumped several protected Amiga NDOS disks with different floppy drives and only recently I started to write stream files back to disk to see whether they'd run on a real Amiga - and they did.

I used the following command:

Code: Select all

dtc -fGemX/track -w -wi4 -k1

I think the "-k1" Parameter (track distance = 80) is mandatory for Amiga disks.

Hi Sky76

What drive are you using to read your Amiga disks with the Kyroflux and what diskettes are you using to write the new images?

[sky76]

Backup and restore with Alps DF354 H168F (similar to another ALPS drive, only with silver front panel) or Mitsumi D359M3 - both are IBM HD floppy drives. For restoring the images I used mint Sony DD floppies. And everything on 3,5" of course.

[Sirswift89]

I thought you had to use a 720k drive to write the tracks to DSDD diskette, otherwise only another HD could read the tracks.

[mr.vince]

No. 3.5" HD drives can write DD disks unless the drive is broken or badly constructed.