Project Kryoflux – Part 5: Making use of the Images

Okay, so after all of that, you have your images – but what to do next? It may not be obvious to all, so I felt like I should at least make a little note about how to deal with them.

STREAM files

The STREAM files recorded by the Kryoflux may be bulky, and you might wonder why you would keep them if the data you are really interested in is in the sector images anyway (and was read correctly). There are several good reasons to keep your STREAM files if you can –

  • At a later stage you can convert these into DRAFT files which are smaller, and retain the high resolution flux data including gaps, sync bytes, protections and noise which don’t appear in the sector images thus later allowing you to access it “more closely resembling the original”. This may be important for copy protected software for example.
  • You can re-use the STREAM files and reprocess them with different sector image settings – this could be helpful if your emulator of choice happens to “want” a different type of image file, without resorting to further conversions from already-stripped-down (information wise) sources.
  • Later decoding algorithms could possibly remedy decoding flaws or increase decoding performance, and you can benefit from this without re-reading your physical media.
  • You could make several reads and “move” track files between reads with different drives to repair a disk which has non-overlapping bad tracks when read with two different drives.
  • You could possibly analyze the stream files for your own amusement and visualize them.

As the STREAM files are hardware specific (to the Kryoflux), there’s really no reason or incentive for emulators to support the format, as they have to implement a computationally expensive software decoder that emulates the floppy controller and interprets the fluxes into syncs and data. And that if another device happens to come along, the format would be different.

Sector Images

Your sector images often contains the most useful data – the data a properly formatted disk would present to the OS/software when accessed. I’ll concentrate on IBM/PC formatted disks and Mac formatted disks as they were the ones I’ve recovered and I have become familiar with them.

Essentially, you have two options. If the files are what is important to you, and software to read them are still in existence, then you can extract the files from the image. But if it is software on the disk you are interested in, you really have little choice but to emulate the target system and install the software and run it as you would if you had such a system.

IBM/PC Formatted Disks

I’ll start off with the easy ones. IBM/PC formatted disk images are easy to handle since the format has been around since (quite literally) forever! File extraction can be performed with WinImage (a software I have used since the Windows 3.11 days) or even with competent hex editors like WinHex (using the Interpret File as a Disk option under the Tools menu). Doing so under WinHex can even allow you to extract deleted files. Unfortunately, none of these are free …

Another way which is – use Linux. If you have Ubuntu or a similar Linux installed, you can mount the image as a loop device with appropriate offset (you will need to calculate it so that the loop device starts with the file system). The advantage is that this also works for HFS formatted Mac floppy disks as many Linux kernels do support HFS at least for reading.

In terms of emulation, things you would likely be interested in at the time would have likely run under MS-DOS. Almost universally, running old software and games is the domain of DOSBox which is a free emulator which supports speed control as well as sound card emulation. Very handy for old DOS games and very multiplatform as well – even running on Tablets!

But if you have an old PC sitting around, the silly but practical thing could be to write a copy of the disk from the image (if not copy protected) and run that in an actual machine for the most authentic feel.

Mac Formatted Disks

Recovering files from Mac formatted disks is easy if you have a Mac. In fact, you just rename your images from .img to .dmg (disk image) and then double click to mount. Could not be easier.

If, say, you don’t have a Mac, the Linux route of mounting it as a loop device also works just fine. So give that a go.

But if you really must absolutely use a PC – there is a way. Aside from more commercial, and rather abandoned software, there is HFVExplorer – a relatively old software from the Windows 98 days which allows you to open HFS formatted disks from images (provided you rename the image to .dsk) and drag the files off to your hard disk. Aside from some graphical glitches, it does work even on Windows 7 x64 bit edition.

There is a bit of a catch – the older 400k formatted disks likely use MFS which predates HFS. This file system isn’t supported by most things, and support for it was removed from MacOS progressively, so it’s wise to copy it over under emulation instead. HFVExplorer doesn’t support HFS+ (or MacOS Extended), so avoid formatting your virtual hard drives with this despite the efficiency benefits. Also avoid using disks which have been renamed .dmg and mounted on Mac OSX as OSX

There are a few caveats to cross platform copying which should be noted. First of all, Apple files have multiple forks which are associated with one file. Unfortunately, earlier PC filesystems did not support this, and many different incompatible ways were used to store this information (such as the RESOURCE.FRK folder, or embedding it into a ZIP archive) and in many cases this is lost altogether. Files without the resource fork are considered to be somewhat forensically compromised as some data was lost in translation which may not matter too much for a Word document but can mean that applications copied from a Mac disk to a PC and back to a Mac disk fail to function at all. Keep this in mind.

The best thing is just to keep it all Mac if you want to keep the fidelity of the data. Unfortunately, even MacOSX users are in a bit of trouble especially those running the later versions (10.5+) as Classic environment was officially depreciated and dropped. The answer to this is to look into several emulators, namely:

Why the three emulators you ask? Well, I asked myself the same thing until I realized that each of the emulators had unique shortcomings which meant that some things were best done with one rather than the other.

Mini vMac emulates only the older Macs. Itself, it emulates a Macintosh Plus. The screen on it is small, and black and white only – but the benefit is that Mini vMac supports attaching of disks of virtually any kind – 400k, 800k, 1440k or even Syquest images. This makes it the ideal thing to use to read our images. There is a bit of a caveat aside from the black and white screen for “everyday” use – that is, while System 7.5.5 will run on the emulator, it will only boot correctly with extensions off (shift key held down during boot). This necessarily means that multimedia relying on Quicktime is pretty much a no-go.

Basilisk II comes to the rescue by emulating newer Motorola 68xxx Macs and thus having colour and better screen resolutions. System 7.5.5 boots fully with extensions on, sound works, and networking is supported. But since it’s only a 68xxx series CPU, it won’t be able to run anything more modern than OS 8.1.

Which is why I recommend having Sheepshaver which emulates a Power PC Mac. This will support running up to OS 9.0.4 as it does not have an MMU and will not support paging. But for me at least, the sound seems broken under Windows, so I have to use Basilisk II if I really want sound. But neither Basilisk II or Sheepshaver support floppy images other than HD 1.44Mb format.

I won’t go into much detail about setting up the emulators as it’s been covered elsewhere but basically, one has to obtain a suitable ROM, generate a suitable blank drive, obtain the system install media/boot disk, boot the emulator from that and install the OS like how you would on a regular machine.

Several tips include:

  • Ignore the cdenable.sys warning on startup – the CD passthrough drivers do not work on any modern OS.
  • If you’re installing an OS from CD, the install will hang on Updating Apple Hard Disk Drivers. You must click options in the last step and untick this to install correctly.
  • Installs of OS 9.0.4 on Sheepshaver will hang when the Setup Assistant gets to the networking section. Don’t bother with the Setup Assistant – just close it when it starts up.
  • Sheepshaver may be quite crashy from time to time – if it’s sound related, tick the disable sound output checkbox and try again.
  • Sheepshaver and Basilisk II may crash on certain programs but not repeatably – you may increase the compatibility at the cost of speed by disabling the JIT compilation ability, and furthermore under Basilisk II, change to a CPU without an FPU.
  • If Sheepshaver or Basilisk II crash on startup, chances are, you need to clear the PRAM. But since this isn’t a real machine – just delete your preferences file and nvram/pram file in the same directory and you should be sweet.
  • If you’re trying to surf the internet in your emulated Mac – Internet Explorer seems to crash Sheepshaver every time. Consider using Netscape (or even better, Classilla).
  • Of course, you’d like to access data from the other floppies on more modern emulators – my suggestion is to first attach your system disk and then your floppy disks and copy the contents over or do the installation under Mini vMac and then swap over to another emulator. You could even use HFVExplorer and open the disk images and copy from one image to the other.

Demonstration Time

Lets start with our 400k single sided disk. Fuji DD 1SThis one is a special disk, because it would have been a very early Mac disk. It read out correctly, and as it turns out, is an MFS formatted disk which is bootable with the original “Finder” which supports one-app-at-a-time.

Mini vMac is happy …


It even runs MacWrite from the disk …

MacWriteApple Macplus Tour

Lets get a little more fun shall we, by playing with the Mac Plus tour disk. It’s bootable as well, as the Mac Plus didn’t have a hard disk, and it’s an 800k disk (hence the Double Sided designation on the shutter). I remember playing with this and being amazed that figures were animated and in motion. Unfortunately the special effects audio seems to crackle and hum a bit under Mini vMac. It’s glacial in its pace.


Now it’s time for Macintosh Basics. Now this one doesn’t bug up when running under Mini vMac, so I was able to make a video of it in action. Only very few basic sound effects … but much more interesting and interactive compared to the Macintosh Plus Tour.


It’s all thanks to the Kryoflux. There is, of course, more successes – I’ve been able to get many of the software working from original disks, and even other tours, like Clarisworks Hypertour from 1991. But I don’t think the world needs to see much more of this kinda thing as it’s … probably quite boring to most people.


So there we have it. While this may be the last part of the “planned” series, there will be more disks to recover in the future coming from various sources, whether it be friends or the general community. Of course, one doesn’t always look forward to sticking disks into a drive – but until some other stuff happens, I’ll probably not mention much about the Kryoflux … at least, for a while.

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3 Responses to Project Kryoflux – Part 5: Making use of the Images

  1. Pingback: Project Kryoflux – Part 4: The Hidden Secrets | Gough's Tech Zone

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