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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?

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  • As long as the floppies are just using an additional sector per track (often used to increase capacity needed for game files) it should be possible to read them using USB drives.
    – Raffzahn
    Jan 5, 2020 at 22:04
  • @Raffzahn yes but there s more than that. Jan 5, 2020 at 22:08
  • They are however still standard IBM-format floppies, just with an atypical sector count. If they use FAT, as they’d need to if they’re hoping for TOS to do more than just segue into their boot sector, then they might be readable as is even with a non-standard sector count as I think that information goes into the volume description? Though many USB floppy drives hard code the conversion to CHS so maybe not.
    – Tommy
    Jan 6, 2020 at 5:00
  • I’d have to check, but I doubt a USB floppy drive would be able to read extra sectors — USB mass storage supports a very small number of disk formats for floppies, and AFAIK anything else can’t be read at all. Jan 6, 2020 at 8:03
  • @Tommy the games I m talking about don t use filesystems. The atari boot on them directly. The used formatting is written on front of them. Jan 6, 2020 at 17:24

2 Answers 2

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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.

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  • the emulator supports raw dumps and msa. So how can I convert those dumps into dumps like the unix dd command does? I prefer to not use the atari as the 250V plastic inuslation is almost gone. Jan 6, 2020 at 17:22
  • 1
    Alas even MSA uses implicit sector sizes and numbering, so if the protection schemes don't number the sectors in each track sequentially from 1, or if any sector is not 512 bytes in size, or if any track has a different number of sectors from the rest, then those file formats aren't adequate to image your disks (even once the hardware question is resolved). And raw images have the same defects.
    – Tommy
    Jan 6, 2020 at 18:27
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    (and to this fantastic answer I might also throw in the inevitable Rasperry Pi GPIO solution: github.com/picosonic/bbc-fdc — though you'll need some electrical nouse to build it for yourself as I don't think it's available for purchase)
    – Tommy
    Jan 6, 2020 at 18:32
  • @Tommy the games I m talking about aren t commercial. And they are often mixed with craked commercial games. So there should be no protection. Except maybe for the official Tos floppy in French. For raw images, I can specify parameters such as sector size in the Linux 2.4 emulator. Jan 8, 2020 at 15:50
  • I haven't checked for Pasti format specifically, but there are a couple of less expensive open-hardware alternatives to the KryoFlux and SuperCard Pro. Specifically, the Greaseweazle and FluxEngine. Given supply chain issues, the cheapest option for me was to buy a ready-made Greaseweazle V4 from AmigaKit (shipping to Canada was something like $6 CAD) and then take advantage of the superior FluxEngine tools' support for the Greaseweazle hardware.
    – ssokolow
    Jan 29, 2023 at 19:41
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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.

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  • Mots commercial floppies were compatible with Pc floppies. The fact you didn t encountered one doesn t prove anything. The best raw dump tool is Linux block devices (part of every Unix systems) otherwise which allows devices to be read like normal files. The problem is not software, it is physicall. Jan 6, 2020 at 19:28
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    I'm pretty sure a raw dump from a Linux block device would retain only sector contents with an implicit mapping from data to cylinder/head/sector. Which is probably less than you'd get with ImageDisk, that's likely at least to provide data split into sectors with addresses and sizes. Though I think PC hardware with a single drive can't read the data between sectors, which the WD1772 in an Atari ST can to a limited extent, and you'll loose all timing information and any weak bits, and I don't know this tool specifically but declining to preserve sectors with bad CRCs is not uncommon.
    – Tommy
    Jan 6, 2020 at 19:47
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    @user2284570 I've been a Linux user since the 1990s. IMD is a different animal.
    – Brian H
    Jan 6, 2020 at 20:19
  • Would IMD work for reading Amiga disks by chance or only sorta-PC format?
    – bjb
    Jan 7, 2020 at 16:58
  • @bjb No for Amiga disks. It works for other systems because it performs low-level control of the Western Digital FDC and PC type floppy drives to re-create the format of those systems. Amiga doesn't have the same hardware setup since it's an Amiga FDC and slightly different drive.
    – Brian H
    Jan 7, 2020 at 19:29

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