What is Uae (emulator)?

UAE
E-UAE 0.8.27 configuration and control panel
Developer:	Bernd Schmidt (UAE) Toni Wilen (WinUAE) Richard Drummond (E-UAE)
Preview release:	0.8.25
OS:	cross-platform
Genre:	Emulator
License:	GNU General Public License
Website:	[1]

UAE is a computer emulator which emulates the hardware of the Commodore Amiga range of computers, first released in 1985. Released under the GNU General Public License, UAE is free software.

History

UAE was originally called the Unusable Amiga Emulator, due to it not being able to boot. In its early stages, it was known as Unix Amiga Emulator and later with other names as well. Since none of the popular expansions fit any more, the acronym no longer stands for anything, and the software is simply known as UAE -- this occasionally gets backronymed as Universal Amiga Emulator.

Features

UAE is almost a full featured Amiga emulator. It emulates most of its functions:

• Original Amiga chipset, Enhanced Chip Set and Advanced Graphics Architecture
• I/O devices (floppy disk driver, joystick, mouse and serial ports)
• Processor (Motorola 68k)

For software, UAE may use disk images made from original Amiga floppy disks. These images have the file extension of "ADF" (Amiga Disk File). Images of Amiga formatted hard drives can also be made. UAE also supports mapping host operating system directories to Amiga hard drives.

Portability

UAE has been ported to many host operating systems, including Linux, Mac OS, FreeBSD, DOS, Microsoft Windows, RISC OS, BeOS, the Xbox console, and even AmigaOS and AROS, where it allows software that requires the Amiga chipset to be run on PPC-based AmigaOS machines.

Emulation speed

There have been many threads in the past on Usenet and other public forums where people argued about the possibility of writing an Amiga emulator. Some considered UAE to be attempting the impossible; to be demanding that a system read, process and output 100 MB/s of data when the fastest PC was a 66 MHz 486, while keeping various emulated chips (the Amiga chipset) all in sync and appearing as they were supposed to appear to software.

For a long time, UAE was almost entirely unusable but slowly and step by step, it fleshed out its support of the Amiga chipset and by 1998 was able to more-or-less emulate an Amiga 500 at full speed.

Today, UAE is usable, thanks partly to the effort taken to develop it and partly to the big improvements in technology that brought computers many times faster than those UAE was initially expected to run on. Many Amiga games and applications can run smoothly on a Pentium II-era system. The realization that a useful Amiga emulator could be written contributed to an increase in enthusiasm about emulation, which started or sped-up efforts to write emulators for other and often less popular computer and electronic game architectures.

A major improvement was made in 2000 by Bernd Meyer with the use of Just-in-time compilation, which significantly improved the emulation speed, to the extent that average PCs could now emulate some Amiga software faster than any real Amiga. UAE can use as much of the host's power in native mode as possible, or balance it with other requirements of the host OS, or to accuractely reflect the original speed, depending on a user's choice. UAE also provides an RTG-compatible "video card" for the Amiga side of the emulation which is tailored for display on the host hardware, so as not to be limited to the emulation of the original Amiga video hardware.

Project development

There are currently two main forks of the original program:

• WinUAE, designed to run on Windows
• E-UAE, designed to run on other platforms

Today the most active fork is WinUAE, so active and well-developed that the E-UAE is actually porting back to POSIX platforms from WinUAE. WinUAE has reasonable compatibility for most software but, just like a "real" Amiga, for some old games it requires careful configuration in order to match the originally-supported hardware. For example, 68000 code could cause an exception on an emulated 68040, just like it would perhaps do on an Amiga 4000/040.

References

• Announcement by Bernd Schmidt on Usenet, Message-ID: <[http://groups.google.com/group/comp.emulators.misc/msg/000d6d55799c8fb2?dmode=source&hl=en 421jqo$91h@news.rwth-aachen.de]>.
• Announcement by Bernd Meyer of the Just In Time compiler on Usenet, Message-ID: <[http://groups.google.com/group/comp.sys.amiga.advocacy/msg/7641384925acc7e5?dmode=source&utoken=2mXi4zcAAABT3izeGZqQMEyV6xT3IfTXE2QmY8oDF1sAdvcxt9QZTyMa_sdYz5lVn_2UDP88P857iwONH1Yfp8McFSyNlTKa 8nbkst$ta9$1@wombat.cs.monash.edu.au]>.

See also

• Fellow, another Amiga emulator which was released not too long after the first usable versions of UAE, and generated competition beneficial to both projects.
• POSE, Palm OS emulator that is based on Copilot, which in turn was based on UAE's m68k emulation
• TiEmu, Texas Instruments calculator emulator, which uses UAE for the core m68k emulation

External links

• UAE Website
• WinUAE Website
• E-UAE Website
• Amiga Forever Website
• Checklist - Emulator Compatibility lists
• Free and legal game software resources for UAE