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Anyone who’s still into the Atari after forty years knows the situation. The internet is full of old ST disks, but what exactly is this ST format? These downloadable disk files usually end in something like PDSOFT.ST. ST-images are simple dumps of an entire Atari floppy. The file contains every single sector of the original disk in the correct order, as if someone had poured the whole disk straight into a file. No compression, no extra structure, just the raw data. An emulator like Steem or Hatari treats an ST-image exactly like a real floppy. You select it, the emulator mounts it as if it were in the drive and the Atari software on it starts as usual. Real hardware is a different story. TOS only understands actual floppy formats, so an ST file is just a normal file without any link to a drive. If you want to use an ST-image on a real Atari, you need to write it back onto a physical disk or load it through a Gotek. Once that’s done, the resulting disk behaves exactly like the original and runs on any Atari machine.

ST images on a PC

Here’s some good news. I’m providing a small tool based on MCOPY. It makes unpacking ST images quite easy and the handling is absolutely straightforward. You unpack the ZIP somewhere on your hard drive, copy the ST images you want to extract into that folder, and launch ST-Entpacken.exe. That’s all. It doesn’t matter if you’re extracting one image or a thousand. A thousand just take more time.

Download ST-Extractor.EN.rar

The idea is simple. Each ST image gets unpacked into its own folder, always named after the image itself. If everything goes well, the image file is deleted afterwards, so be careful and don’t move your images into that folder but copy them. The tool shows a warning before unpacking anyway, so you’ll see it. The program is freeware and you may share it, pass it on, give it away, host it on your website, and mention it in any Atari forum. The copyright remains with me, which should be obvious.

Unpacking MSA files on a PC

My tool can’t unpack MSA files, but that’s no problem. There’s a program called MSA-Converter for that. It only speaks English and French, but it’s easy to figure out. Its main features are:

• Browsing disk images with the option to add, delete or view files
• Converting between disk-image formats (ST, MSA, DIM, STT)
• Turning ZIP files into ST or MSA disk-image formats
• Displaying the cluster state of a disk image
• Batch ZIP compression for multiple single files
• Duplicate file search, useful for large disk-image collections
• Creating blank disk images with many configuration options
• Bilingual: French and English
• What it cannot do is unpack several images at once for direct use. It can convert ST images to MSA images and read or save single floppies.
• After launching the tool you’ll see the interface in French. Click the Outils menu, then Options. Set Langue to English, close the window with X.

Now don’t be confused if the language still hasn’t changed. You need to close the program and start it again. After restarting, the interface switches to English. Click on File and select either an ST or an MSA image from your hard drive. If the extraction works, the program shows you the contents of the image in a separate window.

You can now extract these files to your hard drive. You can also delete files inside the ST image, move them, or create a new folder. If you want to copy files, select the ones you need, right-click them, and choose Save. You can save them either to a floppy disk or to your hard drive.

 

Unpacking ST images into MSA

At first that sounds pointless, but many users convert ST images to MSA because MSA is far more common on real Atari hardware. An ST image always has the full floppy size and older programs often don’t recognize it, while MSA runs reliably thanks to built-in compression and error checking. It’s supported by almost all classic tools like MSA II, JayMSA or MCP and usually loads without trouble. Switching to MSA gives you smaller files and much better compatibility, especially if you work on a real ST or use older utilities.

If you want to unpack one or several ST or MSA images, click Tools and choose Convert a Disk Image. Under Source Files (the green plus icon on the right) you load one or more files. Click MSA and the program extracts ST images and creates an MSA image out of them. The other way around works as well. You can load MSA images and turn them back into ST images. What anyone needs that for, I honestly can’t really say.