How to backup/dump Atari 520st floppy disks on modern hardware

Question

I know the real answer is to download cracked games but from the era before internet got afordable, I have a lot of community games which never reached the Internet and that I would like to rescue as some floppies start to no longer be readable.

As you know, the Atari system uses standard 3.5 inch floppies and can read PC floppies. But in my case almost all floppies are formatted using the Atari specific method which allowed them to put more data per floppy than on a floppy in a PC.

I have the official external floppy reader but as you might guess, the connector can't be plugged on a modern computer directly.

_{(source: archive.org)}

The Atari still works but the 250-volt electrical insulation is almost gone and many keys on the keyboard stopped working (other than that games are still playable if being careful). So I prefer using the external drive (maybe buying a SCSI/IDE converter).

How can I dump those community games in the MSA or RAW format in order to load them inside my Android phone emulator?

Answer 1

There are two problems here: dumping the disks, and loading them in your emulator.

The general answer

To dump Atari ST disks, you can use Pasti on your Atari computer; the advantage is that it works quite well, and won’t require any extra hardware. Using modern hardware, you’d probably have to look into a KryoFlux or SuperCard Pro, or hardware/software combinations which can produce KryoFlux or SCP raw images (such as Greaseweazle or FluxEngine controllers), and Aufit, which converts KryoFlux or SCP dumps to Pasti format. Note that dumping to Pasti images means you then need to carefully check the result — Pasti can’t determine whether a bad read reflects a bad floppy or dirty head, or a copy-protection mechanism.

To load images into your emulator, assuming this is an emulator you’re writing, you’d have to add support for Pasti images. Otherwise, you’ll have to ask the emulator’s author, if it doesn’t already support them... There’s a Windows DLL (see the first Pasti link above) but that’s not going to be all that easy to use on Android.

For straightforward images, using modern hardware

If your disks use one of the formats supported by USB floppy drives, and you only need to dump the raw sector contents, that’s the simplest option: there are a number of tools for current operating systems which can read a floppy using a USB drive. On Linux, any tool which can read from the block device corresponding to the drive will do: dd, cat...

If you can’t find a USB floppy drive capable of reading your disks (and there might not be one), the next step is again devices such as the KryoFlux or SuperCard Pro. They come with tools to read MFM floppies’ contents, and dump images containing only the sector contents.

Answer 2

I have always gotten good results with ImageDisk (IMD) running on a retro PC under MS-DOS. You need a machine that has a compatible floppy controller, which most of the PC's from the 1980s and 1990s did. From the IMD manual:

ImageDisk is a program to read entire diskette images into files (type .IMD), and to recreate a copy of the diskette from that image. A detailed analysis is performed on the diskette, and information about the formatting is recorded in the image file. This allows ImageDisk to work with virtually any soft- sectored diskette format that is compatible with the PC's type 765 floppy diskette controller and drives.

My testing of IMD with Atari ST images is limited, but it is certainly an easy thing to try if you have access to a sufficiently vintage DOS PC.

You can download IMD from Dave's Old Computers. The ZIP file includes pretty good documentation and the program has built-in help to explain the many things about the disk format that can be tweaked.

I have always found IMD to be very capable with floppies and images that are from machines that used the same basic floppy controller family as was used for PC clones - Atari ST, BBC, TRS-80, etc.