HxC mount

What is HxCmount ?

HxCmount is a piece of software for your Atari ST that transform your HxC Floppy Emulator SD card into a hard disk emulator. Once loaded, you will be able to use a new disk letter (C: for example) exactly as a hard disk partition, the only thing is that the partition resides on a image file on your SD card.



The software requires: It has been tested on a regular Atari STE with 512KB of memory, and on an Atari Falcon.


The software has been tested with a basic configuration (ICD hard disk driver on Atari ST and HDdriver on Atari Falcon). It may me buggy on your computer. Please report your problems if you have any.


As with all new software, this release of HxCmount has not been thorougly tested on a large selection of hardware. Test it before using it and putting important data on your new emulated hard disk. Make backup copies of your image file on a regular basis.


Remember that the hardware is still used to access your partition. Every bytes must go through the FLOPPY disk interface. As it is a slow data bus, do not expect hard disk-like performances. However, thanks to the author of the Hxc FE hardware, the data transfert is used at burst mode. It is much, much faster than a real floppy disk. And, for the most part, the drive head seek are virtually instanteneous, probably faster than on a real hard disk. All in all, HxCmount permits "near-usesable" speed. To further improve read and write performance, you should use a fast SD card. Even if floppy data rate is many times slower than the slowest noname SD card, it has been mesured real timings differences between a Class 4 SD card a Class 6 and Class 10 SD card. If you must choose between a 8 GB, class 4 SD Card and a 1 GB class 10 SD card, choose the class 10. 1 GB is still overkill for the Atari, anyway...

How to use it

The emulator is simply a program named HXCMOUNT.PRG. The easiest way to obtain it is to download a package on this page as the package contain a file named HXCMOUNT.HFE that you can directly put on your SD card. Use AUTOBOOT.HFE of the buttons on your HxC Floppy Emulator device to select the file HCXMOUNT.HFE, then boot your Atari ST. The package also contains two sample image files : IMGFULL.IMA, a full featured hard disk image with a lot of program to test, and IMGBLANK.IMA, a completely blank hard disk image.

You have to put exactly ONE file named IMG*.IMA in the ROOT of your SDCARD. The file must *not* be fragmented, so starting from a blank, freshly formatted SD card is a good idea.

Once on your Atari desktop, open the A: drive and launch HXCMOUNT.PRG.

If the driver loads correctly (i.e. Success. New drive mounted as C:), a new partition will be available. Use the GEM desktop to create a new icon, using the drive letter that HXCmount gave you before exiting. ('Install new icon' or 'Install new disk unit' depending on your TOS version). If your TOS version is >= 2.5, you can press "ALT+C" to get access to your C: drive.


The first version of the program has many limitations. Some of them will be (hopefuly) removed from next releases.

File formats

The SD card can have some partitions, but only the first one is read. The SD card must be formatted with a FAT32 file system. The TOS also has limitations : 65536 sectors, and 32765 clusters. The image files bundled with HxCmount are 32MB. It is possible to have greater partitions, but you must you 512+-byte sectors. This is how the ICD and HD hard diks drivers do. Future releases may be bundled with larger images.

Tips and tricks

It is possible to load desktop accessories. For that, you must change the resolution after starting HxCmount. After changing resolution, the TOS will scan the first drive for desktop accessories. It requires that there is no already present hard disk on the system, and that you can switch resolution. This is not possible on a atari ST in mono resolution.

Even if the data transfert rate is much faster than a standard floppy, it is still slow. To speed up program starting, you should compress them on order to reduce data load time.

In order to speed up even more, a disk cache program will probably improve performance at the cost of memory consumption. Unfortunately, these program often requires a AUTO program. To try it, create a AUTO folder on your floppy disk and put the cache disk program ("Turbo Cache" for example), then put HXCMOUNT.PRG. This has not been tested.

Source code

You can download the source code with svn. Issue svn checkout svn://svn.atomas.com/hxcmount/ hcxmount to download a working copy of the source.

Update: Jeff created a sourceforge repository with a folder dedicated to HxCmount. The source will move into it soon.


These features are not yet implemented: These features are not implemented, and probably never will:


Why I have to use an Image file instead of directly use the files from the SD Card ?
There are three reasons:
  1. because the driver really emulate a hard disk partition, with sectors, exactly like a real hard disk. Doing file emulation is very different and require completely different techniques. Since the partition emulation is raw, any software can use it. It may also be possible to use a different File System (Minix, maybe ?).
  2. the TOS only knows FAT12 and FAT16. It doesn't recognize FAT32 and VFAT. You would have to format your multi-GB SDCARD in FAT16 (with limitation up to 512 MB). Formatting it is really not something easy to do. Even with that, it would require huge memory for the simple 520 ST to handle a partition that large.
  3. finally, I wanted to have access to multiple hard disk images, the same way the original HxC hardware can use multiple .HFE disks. This is not yet implemented, though.
I don't care about M$ Windows. My linux can format anything anyhow. using it that way would allow direct access from my PC Operation System to the files on the SD card !
You can ! Under Linux with FUSE: use mount -t vfat /path/to/the/sdcard/image/file /mnt
How to create a new image file ?
Use Winimage. File, New, "Select custom image format". File System: FAT12/16, total number of sectors: 65000. Recommended sectors per cluster: 4.

Winimage is limited to 512-byte sectors. Atari TOS are limited to 65536 sectors, so it is not possible to create a > 32MB image this way.

How to create a > 32 MB image file ? / I can't use Winimage, how to do it ?
I will provide a way to easily create image files whetever the size or your operating system.

Support / Contact / Questions

Please use the official topic on the official HxC forum.



This product is released under the GNU General Public License.


Version 1.00 (2011-05-13)
Initial release.