Programming:Amiga

This article is about the family of home computers. For other uses, see Amiga (disambiguation).

The Amiga is a family of home/personal computers originally developed by Amiga Corporation as an advanced game console. Development on the Amiga began in 1982 with Jay Miner as the principal hardware designer. Commodore International introduced the machine to the market in 1985, after having bought Amiga Corp. The machine was ahead of its time, sporting a custom chipset with advanced graphics and sound capabilities, and a sophisticated multitasking operating system, now known as AmigaOS. Based on the Motorola 68k series of 32-bit microprocessors, the Amiga provided a significant upgrade from 8-bit computers such as the Commodore 64, the Amiga quickly grew in popularity among computer enthusiasts, especially in Europe. It also found a prominent role in the video production business.

Amiga Corporation

The Amiga's chipset was designed by a small company called Amiga Corporation during the end of the first home video game boom. Wary of industrial espionage, the chipset was codenamed Lorraine during development. Amiga Corp. funded the development of the Lorraine by manufacturing joysticks while seeking investors. The chipset was to be used in a video game machine, but following the video game crash of 1983, the Lorraine was repurposed to be a personal computer. Before Amiga Corp. could bring the machine to market, the company encountered financial difficulties and was purchased by Commodore in August 1984.

Commodore

The first Amiga computer, simply called the Amiga, was released in 1985 by Commodore, who marketed it both as their intended successor to the Commodore 64 and as their competitor against the Atari ST. It was later renamed the Amiga 1000 (or A1000 for short). Revolutionary for its time, it could display 4,096 colors and produce 4 channels of 8-bit stereo digital audio. It is also notable for having the first preemptive multitasking operating system with a color GUI, allowing users to perform multiple tasks at the same time.

In 1987, Commodore released two new Amiga models, the A500 and the A2000. These were marketed as low-end and high-end machines, respectively. The former became the most popular Amiga computer of the decade and served primarily as a games machine, while the latter was marketed as a more serious workstation for graphic purposes, due to the presence of a SCSI controller option, a Genlock slot and a video I/O connector.

In 1990, the A3000 was introduced as the successor to both the A1000 and A2000, with an enhanced chipset (ECS) and the second release of its operating system, which would eventually be called AmigaOS.

In the same year, Commodore released three new low-end machines: the CDTV, aimed to move the platform to the living room; the A500+, with the same enhancements as the A3000; and the A600, basically an A500+ in a smaller box with an IDE controller for hard disks. All of these were commercial failures, mainly due to poor marketing.

Mass-market Amigas were then considerably cheaper than PCs and Macs at the time. This factor helped to boost sales in the more price-conscious European markets, but it also led to Commodore being viewed in U.S. markets as a producer of cheap "game machines". This perception was furthered by the fact that most Commodore retail outlets were toy stores, and marketing campaigns were woefully mismatched with the status-conscious American public. Overall, the Amiga was very successful in Europe, but it sold less than a million units in the U.S..

In 1992, Commodore released their last Amiga computer models, the A1200 and the A4000: Each featured the new AGA chipset and the third release of AmigaOS.

In 1993, menaced by console giants Sega and Nintendo, Commodore marketed the CD32 in a desperate attempt to save their business. The CD32 was one of the earliest CD-based consoles and was also the world's first 32-bit game machine, with specifications similar to the A1200.

Technical features

For its time, the Amiga was quite an advanced computer for the home market. It provided impressive sound and graphics for games, and it was also popular in business environments until around the mid-1990s, aiding users in video editing and 3D graphics.

The very first model, the Amiga 1000, had a 7.14 MHz CPU, designed to work directly with NTSC video. The CPU clock frequency was precisely double the 3.57 MHz color carrier frequency. The A1000 had a built-in composite video output, which allowed the computer to be hooked up directly to a TV or VCR. However, the output signal was considered too "hot" (strong) by many to be useful for anything other than home use (however, this could be remedied by running the A1000's composite output through a video processing amplifier, or "proc amp", to bring the video levels down to a suitable amount).

The Original Amiga chipset, or OCS, was more advanced than other architectures of its time: it had dedicated chips for real-time video effects, allowing users to easily work with genlocks to overlay graphics atop live video. The Amiga's unique overscan feature, the ability to run at custom, user-defined resolutions, allowed it to draw images past the visible borders of a television screen, allowing seamless fly-ins and scrolling from off-frame. Today, many TV stations and broadcast corporations are still using A3000s and A4000s for their real-time video effects. Many programs were also written for creating "fansubs" of foreign films and Japanese animation.

Another unique feature provided by the Amiga was the ability to change display resolutions on the fly — the computer could display different scan lines at different resolutions, allowing for multiple screens of information at different resolutions that could overlap one another without interfering with each other. The chipset also included a blitter, which could copy and manipulate large amounts of graphics data at once (making the Amiga well-suited to arcade action games), and accelerated line-drawing and area-filling functions, which helped advance the popularity of real-time 3D graphics and games. However, the Amiga would later become disadvantaged with the advent of first-person shooter games such as the PC game Doom. This was partly because the Amiga's planar graphics chipsets were less well suited to this type of 3D graphics, compared to the chunky graphics chipsets found on PC and Macintosh computers.

Operating systems

The displayed OS is Kickstart 1.3.The operating system, AmigaOS, was also quite sophisticated for its time, combining an intuitive graphical user interface (GUI) like that of the Apple Macintosh together with an elegant Command Line Interface (CLI) which then eventually evolved into a very powerful Shell. This gives the user of Amiga some of the flexibility of UNIX while retaining a simplicity that made maintenance rather easy. While its operating system was the only preemptive multitasking platform with an efficient message-passing kernel in the consumer marketplace for several years with an efficient memory management, robustness left something to be desired, mainly due to the absence of protected memory, resulting in the famous "Guru Meditation" errors.

The Amiga operating system was resurrected in 2000 as AmigaOS 4, which currently runs only on AmigaOne computers and on A1200s and A4000s with a PowerPC accelerator card.

Other, still maintained, operating systems are available for the classic Amiga platform, including Linux and NetBSD. Older versions of OpenBSD can also be run - the last Amiga release was 3.2. Commodore Amiga Unix (based on AT&T System V Rel. 4) was available only for the A2500 and A3000.

Mac OS on Amiga

Also introduced for the Amiga was the Emplant expansion card, which allowed the Amiga to emulate an Apple Macintosh and run the Macintosh Operating System using the process of translation emulation. It required an Apple Macintosh ROM image, which needed to be obtained from a real Macintosh. The user needed to own the real Macintosh or Mac ROMs to legally run the emulator.

In 1988 an Apple Mac emulator called A-Max was released for the Amiga 500. It needed Mac ROMs to function, and could read Mac disks when used with a Mac floppy drive (Amiga floppy drives are unable to read Mac disks. Unlike Amiga disks Mac floppy disks spin at variable speeds, much like CD ROM drives). It wasn't a particularly elegant solution, but it did provide an affordable Mac experience.

Over time full-software emulation was available, but you still had to get a ROM image. Example emulators include ShapeShifter (not to be confused with the third party preference pane ShapeShifter), later superseded by Basilisk II (both by the same programmer who conceived SheepShaver, Christian Bauer), Fusion and iFusion (the latter ran classic MacOS using translation emulation with a PowerPC "coprocessor" accelerator card).

This form of emulation has been said to equal or better the speed of a Macintosh with the same processor, especialy with respect to the m68k series due to real Macs running in MMU trap mode, hampering performance. Moreover, in the period when no new 68k Mac models were being developed and the majority of Mac software was not natively available on PowerPC Macintosh yet (but only runnable through a slow 68k emulation), the fastest "Macintosh" machines around were actually by far Amiga computers with 68060 CPUs running ShapeShifter or Fusion.

One should note that although Amigas were very successful at emulating Macintoshes, it was never considered to be a Macintosh clone as it could not use MacOS as a primary operating system.

Amiga Emulators

Many Amiga users actually use a system that boots directly into the emulator.

There is the Unix Amiga Emulator (UAE) that can emulate a full system on Macintosh and Intel systems, including undocumented behavior and the custom chips. Also there is a special Windows port, WinUAE.

There is a commercial product Amiga Forever that includes an emulator and the AmigaOS as well as several other important parts.

UAE

WinUAE

Amiga Forever

WinFellow

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