This information is not current. The concepts
outlined in this page evolved and were implemented in Amiga Forever
2008. Please refer to the
RetroPlatform
Technical Reference for additional
information.
Introduction
Before the launch of Amiga Forever 2005 several parties,
including users, emulation developers and supporters of the
preservation of "Classic" Amiga applications, felt the need to
associate standard configuration information to Amiga application
images (e.g. disk sets in ADF, DMS or other format, CD images, etc.)
Without such information, as memory fades away with the original
hardware, carefully preserved Amiga application media images risk
becoming next to unusable, given a complete lack of information
about the system they were supposed to run on. XADML aims to address
this problem, and several more (e.g. automatic organization of
random collections of unstructured application images, easier access
to application images available online, etc.)
In their simplest form, XADML files provide an XML-structured
short description of a single application, saying something like
"This software ideally requires an A1200 with 8 MB of Fast RAM and
two floppy disk drives, but it also runs on an ECS system. Insert
disk image 1 in drive 0 and disk image 2 in drive 1. The application
supports features such as accelerated CPUs and accelerated floppy
drives." Having this information, an application front-end can list
the application, the user can click on it, and an Amiga emulator can
set up the proper hardware configuration, load the correct ROM and
operating system, and then load the application from floppy in less than one
second, and run it at least 10 times faster than on an A1200. No
configuration is required by the user. Because XADML describes
configurations in terms of "real" combinations of reference
hardware, ROM and operating system, the architecture is shielded from emulation
settings, which are likely to be implementation and version-specific.
A XADML file contains one or more instances of up to five logical
parts:
- Compact Application Description (for display purposes only:
minimal information for front-ends, for maintaining lists of
applications, etc.)
- Media identification data (e.g. file name
and CRC32s of disk images, etc.)
- Configuration Data (describes the system requirements, e.g.
for emulation packages)
- Cataloging data (unique application OID, and OIDs of
entities involved in development and publishing)
- Extended Application Description (extended additional
information)
XADML files are not Amiga-specific. Although the "A"
in "XADML" do bring to mind "Amiga" systems, the "A" may also stand
for a more generic "Application".
XADML Usage Scenarios
XADML files are not emulation-specific. They simply describe an
application in a very compact way (e.g. title, publisher, year,
160x120 thumbnail) and a real computer on which they best run.
Actually, they can describe both an ideal configuration and a
fallback one, e.g. an AGA system and an OCS one, if a game provides
enhanced experience on the former, but also works on the latter, or
two Amiga ROM versions, if a demo works perfectly with a 1.1 Amiga
ROM, but it also works with minor visual problems on a more common
1.3 system. It is then up to an emulation application (e.g. WinUAE,
WinFellow) to convert this information to internal emulation
settings. A few additional tags which may be interpreted as being
emulation-specific are supported in XADML, simply because emulation
is the only means to get features that are very useful (e.g. faster
CPUs, faster drives) and have no equivalent in the original
hardware.
Within the specific Amiga context, it is estimated that over 90%
of games available for download can run using only a handful of
different XADML hardware configuration descriptions. Download sites
are likely to easily and automatically be able to convert their
current configuration instructions, which are often based on
different emulation packages and versions, to more neutral XADML
files.
Although usually an XADML file is included with one application
and its related files (e.g. ADF disk image files), it is possible to
use XADML files without disk images, or a special XADML "advertising"
files describing 100s of games that can be downloaded from a site.
Because XADML files can optionally contain checksum information of
the application image files (e.g. ADFs) they refer to, it becomes
possible to create simple programs that scan an entire hard disk and
automatically associate the correct ADFs with the correct XADML file,
removing duplicates and moving the files in a more organized and
structured way, if so desired.
Using XADML, a game or demo download site can "advertise" the
titles it hosts, so that a front-end application can list all games
or demos even if they are not installed on the local computer.
Installation and running the application then takes only two mouse
clicks. The user does not need to select a download location,
extract the game, or configure the emulation software. Because some
download sites are advertising-supported, or otherwise prefer their
website not to be bypassed from this process, the XADML
specification provides for different ways to respect this, allowing
for XADML-specific links to reside on a web page, which can be opened
in a web browser by the front-end.
XADML in Amiga Forever
XADML as described here is the result of years of experience, work
and exchanges of ideas between, among others, emulation developers,
application preservation experts, and users, and has a first
implementation in Amiga Forever 2005. The success of XADML, which is
at this point is hoped for, would not be possible without the ideas
and material support of Toni Wilen, the lead maintainer of the
WinUAE emulation software, and of numerous additional contributors
(e.g. feedback from the SPS Team). XADML can be seen at work in
the new Demos and Games front-ends of the Amiga Forever 2005
launcher. As emulation developers, download sites and other
interested parties work to better support this, free updates for
Amiga Forever will be made available to extend support for the
system.
Amiga Forever 2005 introduced a new organization of directories
and files on Windows, which includes an "Amiga Files"
folder (support for which was also added by WinUAE 1.0, among others).
Additional Information
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