WinUAE

In the mid-1990s, as Amiga Shopper put it, Amiga owners had one thing to hold on to: “if your PC is so great, how come the Amiga can emulate the PC but not the other way around?” The Amiga’s custom chips “can be reprogrammed at microsecond intervals”, Amiga Format explained, and copying all of that in software looked hopeless. A computer science student decided to try anyway. “The fact that everyone said it was impossible!” Bernd Schmidt told Amiga Shopper when asked why. His UAE grew into the family of Amiga emulators still in use, and its Windows branch, WinUAE, has been developed by Toni Wilen for more than twenty-five years.

Fast facts

Origin: UAE, started by Bernd Schmidt on 25 February 1995; version 0.1 on 1 September 1995
Windows port: by 1997, first by Mathias Ortmann and Brian King
Developer, credited from 1998: Toni Wilen
Runs on: Windows
Current version: 6.0.3, March 2026
Cross-platform relative: FS-UAE

The unusable Amiga emulator

Schmidt’s own changelog starts on 25 February 1995 with “Work begun”. Two days later his 68000 emulation could run “the first couple of KS1.3 instructions”, and on 9 March “something that bears a striking resemblance to the familiar Kickstart logo now appears in my X window!” Release 0.1 followed on 1 September 1995.

It was not much use yet. According to Amiga Format, “UAE originally stood for Unusable Amiga Emulator, with very good reason. Version 0.1 would not even boot.” (Amiga Shopper remembered the name as the “Useless Amiga Emulator”.) Schmidt, then a 22-year-old computer science student with an A500 bought in 1989, told Amiga Shopper that the first version, which “couldn’t boot and only had black and white graphics”, took under two weeks to write, after a long time spent on the design and on decoding “all the 68000 instructions by hand”. By version 0.6 in 1996 the name had become the Unix Amiga Emulator. It ran Workbench and many games, “if they aren’t copy-protected”.

Schmidt said that “making the source available was maybe the best decision concerning UAE”. Other programmers ported it to MS-DOS, the Macintosh, Acorn machines, BeOS and even the Amiga itself. In March 1998 Amiga Format found that a fast Pentium ran UAE at two or three times the speed of an A500, and that it ran “more than half the available software”. It still could not read Amiga floppies on a PC or detect sprite collisions, and it could not deliver the “exact synchronisation” that real Amiga programs relied on. Protected A500 programs were “inaccessible”.

The Windows 95 version came from Mathias Ortmann, whose UAE page was at the Technical University of Munich, with Brian King writing much of the Windows interface and the Picasso96 graphics-card emulation. By April 1999 Amazing Computing reported that “Brian King maintains the WinUAE package”. Toni Wilen appears in the credits from 1998. Brian King’s credit ends in 2001, and the Windows version’s changelog, which begins in the UAE 0.8.22 era, is Wilen’s own record of his work, entry after entry marked “(me)”. WinUAE 1.0 was released on 6 June 2005.

Under Wilen, WinUAE became the most developed branch of the UAE family, and FS-UAE is built on its emulation code.

Cycle-exact

The biggest change was timing. In one pre-1.0 beta Wilen added “unoptimized near cycle-exact cpu and blitter emulation”, which fixed “most programs that expect correct cpu and blitter speed”. It came with warnings: it needed at least 50 per cent more processing power than the normal mode, an “Athlon XP/Pentium IV” was “highly recommended”, and it was “very experimental, timing is quite far from perfection”. Two decades of releases since have refined it; the 6.1 development notes describe the Copper being rewritten as “a relatively simple 3 stage state machine based on Alice schematics”; Alice is the AGA chipset’s version of Agnus.

Today WinUAE emulates the OCS, ECS and AGA chipsets, 68000 to 68060 processors, CDTV and CD32, graphics cards, PowerPC accelerator boards and a long list of expansion hardware. At Assembly 2006 in Helsinki, the Amiga demo Starstruck won the main demo competition, and its makers later wrote that at the party it ran in WinUAE.

Copy-protected disks

Copy protection was what kept UAE from running many commercial games, because an ordinary disk image stores only what a normal drive reads back. WinUAE reads the IPF images made by the Software Preservation Society, which record a disk as it was mastered, and its changelog records support for “raw dumps from Softpres Capture Tool and KryoFlux”. A protected original can run in WinUAE as it was sold; disk protection explains why that matters.

Kickstart ROMs and Amiga Forever

To run Amiga software properly, UAE needs a copy of the Amiga’s Kickstart ROM. In 1996 Amiga Shopper explained how to copy one from a real Amiga with a CLI command. The ROMs and Workbench disks are still copyrighted, so emulator authors cannot hand them out. By early 1998 the software company Cloanto was selling Amiga Forever, a CD with UAE for Windows, Workbench and Kickstarts “from 1.0 to 3.0, licensed to Cloanto by Gateway 2000”, the company that then owned the Amiga technology. Amiga Format called it “a commercial product for Amiga nostalgics loath to copy or steal Kickstart and Workbench”. Amazing Computing noted that later editions shipped “the latest version of WinUAE tested by Cloanto”. Amiga Forever is still sold, now in its eleventh version, and WinUAE’s settings still link to it. Without a Kickstart, WinUAE can boot a free replacement ROM from the AROS project, which runs some software but not all.

Released source code

UAE’s source was public from the early releases and is under the GNU General Public License. WinUAE’s source code is published on GitHub by Toni Wilen.

Sources

UAE ChangeLog, carried in the WinUAE source (web, secondary): “Work begun” on 25 February 1995, the Kickstart logo on 9 March 1995, “Release 0.1” on 1 September 1995. https://github.com/tonioni/WinUAE
WinUAE source code, od-win32/win32.cpp credits and od-win32/winuaechangelog.txt (web, secondary): credits for Schmidt, Wilen (from 1998), King (1996–2001) and Ortmann (1996–1999); WinUAE 1.0 on 6 June 2005; the near cycle-exact beta; KryoFlux and Softpres raw dump support; the 6.1 Copper rewrite. https://github.com/tonioni/WinUAE
Amiga Shopper issue 70, Christmas 1996, pp. 12–14, David Taylor, UAE feature and interview with Bernd Schmidt: his age and A500, “Useless Amiga Emulator”, version 0.6 and the Unix Amiga Emulator, copying the Kickstart, the opening question about emulating the Amiga, the quotes on why he wrote it, how long it took, copy protection and making the source available.
Amiga Computing issue 115, August 1997, UAE feature by David Taylor: the Windows 95 version and Ortmann’s page.
Amiga Format issue 108, March 1998, pp. 20–23, UAE and emulation feature: the custom chips “reprogrammed at microsecond intervals”, “Unusable Amiga Emulator”, the ports, speed and compatibility, limitations, Amiga Forever and its licence from Gateway 2000; NetConnect 2 preview, pp. 78–79: “a concerted push of Amiga technology by Gateway 2000 and licenced Amiga developers”.
Amazing Computing, vol. 14 no. 4, April 1999, Amiga Forever review: “Brian King maintains the WinUAE package”; vol. 14 no. 9, September 1999: Amiga Forever 3.0 with “the latest version of WinUAE tested by Cloanto”.
WinUAE home page (web, secondary): version 6.0.3, March 2026. https://www.winuae.net/
Amiga Forever home page (web, secondary): Amiga Forever 11 on sale. https://www.amigaforever.com/
Kalms and Emoon, “Final version of Starstruck”, release notes, 2018 (web, secondary): the demo ran in WinUAE at Assembly 2006. https://files.scene.org/get/parties/2006/assembly06/demo/tbl-starstruck-finalversion.zip
Wikipedia, “UAE (emulator)” (web, secondary): the GPL licence and AROS ROM replacement. https://en.wikipedia.org/wiki/UAE_(emulator)