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FAQ: Disk Images

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Even though some visitors want to 'just play' the games (thus we're offering pre-installed versions of the games where possible), many collectors prefer the original format. To transfer this, so-called disk images are necessary, i.e. images of the original floppy disks or CDs.

There are many different formats of such images. Unfortunately, many have just been invented by companies for use with their own programs and these formats haven't been publically documented. Therefore, these formats can only be read with the respective (and sometimes costly) applications. Games archived this way can only be used by a selected few who own the right operating system and application, which is pretty much the antithesis of preservation. That is why we're only using formats which can be read using software which is freely available for any common operating system. Other formats, such as NRG (Nero), CCD (Clone CD) or MDF should never be used.

CD-Images

ISO-9660

As the name suggests, this format is an international standard and it is supported by virtually every application out there. It should always be first choice for CD images if the CD consists only of one track (which is usually the case with games).

To find out about the number of tracks on a CD, you can use various burning applications. Here are two examples using cdrecord and cdrdao respectively:
cdrecord -toc
cdrdao disk-info
Many graphical applications can extract and show track information as well, of course.

ISO files can be created using countless applications. The following example uses the command line tool dd which is available in any Unix-ish system (MS-Windows version here: http://www.chrysocome.net/dd).
dd if=/dev/cdrom of=cd.iso
dd if=\\.\d: of=c:\cd.iso
Graphical burning applications usually use menu items like 'create image'. After that, select the ISO format. On MS-Windows, you might want to give the free CDBurnerXP a try

ISO images you downloaded can either be mounted (i.e. used as a virtual drive) or burned to a physical CD. An example:
mount -o loop cd.iso /mnt/temp
In MS-Windows, you need additional tools (e.g. Daemon Tools) to achieve the same effect. ISO images can be burned with any burning application.

BIN / CUE

If a CD consists of more than one track (for games, that is usually one data track and additional audio tracks), this is the preferred format. It consists of the image itself (BIN) and a text file describing the kind of tracks and their borders (CUE). Application support of this format isn't perfect, but still very good. Note that RAW / CUE and BIN / TOC are basically interchangeable names for the same basic format idea.

Such images can't be created using the common dd tool. Many burning applications have an option for it, though (e.g. something like 'create image' - 'format' - 'BIN/CUE').

Mounting can again be done with Daemon Tools (MS-Windows) or with CDEmu (Unix). Just burning the image might be easier in this case, though.

If, after burning, you only hear noise instead of music, this is most likely a problem of byte order. In cdrdao, you should try the following:
cdrdao --driver generic-mmc:0x20000

Floppy-Images

Floppy disks never have numerous tracks, so making a difference in file formats isn't necessary in this case. Handling everything like ISO-9660 CD images is perfectly sufficient.

Creating floppy images can again be done with dd:
dd if=/dev/fd0 of=disk.img
dd if=\\.\a: of=c:\disk.img bs=1440k

These are the respective commands to write an image back to a disk:
dd if=disk.img of=/dev/fd0
dd if=c:\disk1.img of=\\.\a:

The MS-Windows version of dd is, unfortunately, not quite as intelligent as its Unix counterpart. If reading a disk takes too long, setting the disk capacity manually may help, i.e.:
dd if=c:\disk1.img of=\\.\a: bs=1440k

For those who are generally afraid of command lines, RawWrite is the recommended choice. This tool only reads and writes disks with 1.44MB capacity (i.e. 3.5" HD). This is the most common format of the time period predominantly covered on this site, so in most cases, it should be fine. The flexibility of dd is lost using this alternative tool, however.
Floppy images generated this way can be mounted just like ISO-9660 images:
mount -o loop disk.img /mnt/temp

Because floppy disks are less reliable physically than CDs, many old games may already have become faulty and unreadable. dd_rescue is worth a try in such cases. While the regular dd just quits execution if it encounters a read error, this tool tries again and again:
dd_rescue /dev/fd0 disk.img
If even that doesn't help, you should stop trying to extract the data yourself, because it is most likely you'll just damage the data further. If the disk contains very valuable or rare files, a company specialized in data recovery might help. However, this can obviously become costly and it is, in spite of everything, still unlikely to succeed.
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