Hi Attila,
nice to meet another Atari ST-User

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I'd be interested in your rare Atari ST control floppy disk,too.
Creating an image of your Atari ST disk is quite easy. Here's how I would do it:
1. Format two disks on your Atari ST using a format/copy-utility which is able to create a MSDOS-compatible disk (I suggest FCopy 3.0 or FCopy Pro)
2. Insert your newly formated disk in your PC floppy drive
3. Download the Magic Shadow Archiver (MSA)
here and extract the zip file to your newly formated disk

4. Insert the disk in your Atari ST and launch the Magic Shadow Archiver (this is a programm which is able to create an image file containing selected (or all) tracks of a disk)
5. Eject the disk and insert the other newly formated disk.
6. Click on the field where the headline reads "Filename, click to change". I always used the program with multiple drives (floppy disk drive / hard disk), but in case you only use one floppy disk drive, I would suggest, according to the Atari ST manual, to enter B: (for a simulated second disk drive) in the file selector. Enter a name for the disk image, you'd like to create (for example DLCONTRL.MSA) and confirm your choice by clicking on the "OK" button in the fileselector.
7. Eject the disk and insert your Atari ST DL control floppy disk.
8. Make sure, drive A is selected
9. Make sure, the left button in the middle row states "DISK->FILE" (
not "DISK<-FILE")
10. Click on the "ANALYZE" button and write down the disk geometry, which is now displayed
11. Enter the disk geometry (sides, sectors, tracks) in the appropriate fields and make sure, that the field "TRACKS" begins at track 00 and ends at the last track of your disk (watch the informations about the disk geometry, which you'll get after clicking on "ANALYZE"). Entering wrong values here could result in a partial disk image which wouldn't run.
12. Now click on "Do it!" - the program should now start to read your Atari ST DL control floppy disk track by track. Depending of how much RAM your Atari ST has built-in, you'll be requested for a different number of times to exchange the Atari ST DL control floppy disk for your previously newly formated disk.
13. If everything worked fine, you should now have a disk image of your Atari ST DL control floppy disk on your previously formated disk called DLCONTRL.MSA (or whatever name you've chosen).
14. Insert the disk containing the disk image DLCONTRL.MSA in your PC floppy disk drive and upload it to the forum

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I made this step-by-step guide from memory and I hope, I remembered correctly. It reads difficult, but it's quite simple to do.
Follow my guide on your on risk. Always leave your Atari ST DL control floppy disk write-protected.In case you are running into problems, just PM me and I'll try to assist you. I would also offer to do the creation of the disk image for you, if you'd agree to send the Atari ST DL control floppy disk to me (by registered mail).
Your Atari ST DL control floppy disk really is a rarity and is worth to be preserved.
Do you have a control disk for your Software Corner PAL Space Ace laserdisc, too?