The Amiga is a family of home/personal computers originally developed by Amiga Corporation as an advanced home entertainment and productivity machine. 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 sported an custom chipset with advanced graphics and sound capabilities, and a sophisticated pre-emptive multitasking operating system, now known as AmigaOS. Based on the Motorola 68k series of 16-bit and 32-bit microprocessors, the Amiga provided a significant upgrade from 8-bit computers such as the Commodore 64, and the Amiga quickly grew in popularity among computer enthusiasts, especially in Europe. It also found a prominent role in the video production business.

History

The Amiga was originally designed by a small company called Amiga Corporation as the ultimate video games machine. Before the machine was released into the market, the company was bought out by Commodore, and it was redesigned into a real, general-purpose computer. The first model, called the Amiga 1000, was released in 1985 as a successor to the Commodore 64 and a rival to the Atari ST.

Commodore later released several new Amiga models, both for low-end gaming use and high-end productivity use. Throughout the 1980s, the Amiga's combination of hardware and operating system software offered immense power, but in the late nineties and early twenty-first century, other platforms, most of all the PC, reduced or eliminated this advantage.

Hardware

At the time of its introduction in 1985, the Amiga had what was a complex overall architecture, featuring co-processors suited for audio and visual tasks. With its stereo sound, comparatively large colour palette and brisk performance (due largely to the custom chipset) - not to mention its multitasking abilities - the Amiga was considered by some to be superior to all competing systems, despite competitors offering faster CPUs, higher resolution monochrome graphics and (in some cases) built-in MIDI.

The platform had three significant upgrades (not counting non-Commodore technologies), with the Amiga 2000 in 1987, Amiga 3000 in 1990 and the Amiga 4000 in 1992. These upgrades improved the platform's graphical abilities, allowing for more colors and different display modes, and added expansion slots and ports. The best selling models however, were the much cheaper but still remarkably versatile console models, the Amiga 500 (based on the 68000 CPU and OCS chipset, see below) and the later Amiga 1200 (with a 68020 and AGA chipset).

Central Processing Unit

All Commodore Amiga models make use of Motorola CPUs based on the Motorola 68k architecture. Introduced by Motorola in 1979 the 68k CPU family has powered numerous computer and game systems, including the Atari ST, Apple Macintosh, Sega Genesis, Sun Microsystems.

On some Amigas the CPU was fitted on a daughterboard, called a CPU card, which could be replaced with a faster one. Other Amigas came with CPUs either socketed or embedded on the motherboard, but it was possible on virtually all Amiga models to upgrade the CPU via an expansion slot. For example, the standard 7Mhz 68000 CPU in the A500/A2000 could be upgraded with an "accelerator" card containing a 68020 or 68030 CPU, giving greatly increased performance. The most common accelerator cards for the A500/2000 were probably the 68030 25Mhz and 33Mhz models, but '030 cards could be made to run as fast as 50Mhz. Later, 68040, 68060 and even PowerPC-based accelerator cards became available. Commodore sold a limited selection of its own accelerator cards, but third party manufactures offered CPU upgrades for all Amiga models. Accelerator cards often came with both extra RAM slots and SCSI hard drive interfaces in order to maximize performance and value, and were very popular amongst users who were able to afford one.

Trivia:

• It was possible to do a direct socket replacement of the standard 7Mhz 68000 CPU with a 68010 CPU. The 68010 executes instructions slightly faster than the 68000, but the conversion also introduces a small degree of software incompatibility.
• For PowerPC-based accelerator cards, only PPC aware software and libraries were able to take advantage of the PPC CPU.
• The very first model, the Amiga 1000, had a 7.15909 MHz 68000 CPU (7.09 MHz for PAL machines). This is precisely double the 3.58 MHz NTSC color carrier frequency, and was needed by the Amiga chipset when outputting NTSC video. All frequencies in the Amiga 1000 are derived from this frequency as it simplified glue logic and allowed the Amiga 1000 to make do with a single cheap mass-produced crystal.

Custom chipset

The Amiga's custom chipset, as the name implies, consists of a number of chips.

There are three generations of chipsets used in the various Amiga models. The first is OCS, followed by ECS and finally AGA. What all these chipsets have in common is that they handle raster graphics, digital audio and communication with between various peripherals (e.g. CPU, memory and floppy disks) in the Amiga.

Trivia:

• The Amiga was one of the first computers for which one could buy cheap accessories for sound sampling and video digitization. This means that not only can the Amiga produce computer-generated images and sound, but users can input "real" images and sound for editing, composition, and use in computer games.

Graphics

Sound

The sound chip, named Paula, supports four sound channels (2 for the left speaker and 2 for the right) with 8 bit resolution for each channel and a 6 bit volume control. The analogue part of the chip is connected with a low-pass filter, filtering out the many high frequencies often created in computer systems.

Trivia:

• Software such as Octamed use software mixing to allow 8 or more virtual channels, and astute composers can mix two hardware channels to achieve 9 bit resolution, or all four to achieve 10 bit resolution.
• Programmers developed a 14 bit stereo output routine by combining channels and volume controls with the existing 8 bit sound resolution.
• In the PC/Amiga/ST rivalry, the quality of the Amiga's sound output, and the fact that the hardware is ubiquitous and easily addressed by software, were standout features of Amiga hardware that the PC lagged behind for years.
• Paula can read directly from some of the system's memory (chip ram), using direct memory access (DMA), making sound playback without CPU intervention possible.
• There are third party sound cards that provide DSP functions, multitrack direct to disk recording, multiple hardware sound channels and 16 bit and beyond resolutions. Later a retargetable sound API called AHI was developed allowing these cards to be used transparently by the OS and software.
• The brightness of the Amiga's power LED is used to indicate the status of the Amiga’s low-pass filter. The filter is active when the LED is at normal brightness, and deactivated when dimmed. Older Amiga 500's simply turned off the power LED.

Speech synthesis

In the original 1.x AmigaOS releases, a Say program demo included with AmigaBASIC programming examples. For 2.0, Say became a standard utility program which did not need AmigaBASIC.

Third party hardware

The most popular upgrades were memory, SCSI controllers and CPU accelerator cards. These were sometimes combined into the one device, particularly on big box Amigas like the A2000, A3000 and A4000.

Early CPU accelerator cards feature full 32bit CPUs of the 68000 family such as the 68020 and 68030, almost always with 32bit memory and usually with FPUs and MMUs or the facility to add them. Later designs feature the 68040 and 68060. Both CPUs feature integrated FPUs and MMUs. Many CPU accelerator cards also feature integrated SCSI controllers.

Phase5 designed the PowerUp boards (BlizzardPPC and CyberstormPPC) featuring both a 68k (a 68040 or 68060) and a PPC (603 or 604) CPU, which are able to run the two CPUs at the same time (and share the system memory). The PPC CPU on PowerUp boards is usually used as a coprocessor for heavy computations (a powerful CPU is needed to run for example MAME, but even decoding JPEG pictures and MP3 audio was considered heavy computation in those years). It is also possible to ignore the 68k CPU and run Linux on the PPC (project Linux APUS), but a PPC native Amiga OS was not available when the PPC boards first appeared.

There were/are also available 24 bit graphics cards and video cards. Graphics cards are designed primarily for 2D artwork production, workstation use, and later, gaming. Video cards are designed for inputting and outputting video signals, and processing and manipulating video.

Perhaps the most famous video card in the North American market was the Newtek Video Toaster. This was a powerful video effects board which turned the Amiga into an affordable video processing computer which found its way into many professional video environments. Due to its NTSC only design it did not find a market in countries that used the PAL standard, such as in Europe. In PAL countries the Opalvision card was popular, although less featured and supported than the Video Toaster.

Various manufacturers started producing PCI busboards for the A1200 and A4000, allowing standard Amigas to use PCI cards such as Voodoo graphic cards, Soundblaster sound cards, 10/100 ethernet and TV tuners.

PowerPC upgrades with Wide SCSI controllers, and PCI busboards with ethernet, sound and graphics cards, and towerised cases allowed the A1200 and A4000 to survive well into the late nineties as modern and competitive machines.

Models and variants

Classic Amiga models, from the 1000 to the 4000T, were produced from 1985 to 1996. Since then, no new generations of Classic Amigas have been produced. In addition, some companies released unofficial Amiga clones. AmigaOS 4 and beyond will run on both Amigas equipped with CyberstormPPC or BlizzardPPC accelerator boards, and on the PPC Teron series based AmigaOne computers.

Emulating the Amiga

Some modern-day "Amiga users" actually emulate the machine on modern hardware rather than running their software on the original hardware.

Operating systems

AmigaOS

At the time of release AmigaOS gave the average consumer the experience of an OS quite ahead of its time. It was the first commercially available operating system to implement pre-emptive multitasking ^*. Other features included combining a graphical user interface with a command line interface, and allowing long filenames permitting whitespace, not requiring a file extension.

However, like some other operating systems of the time, the OS lacked memory protection. While the decision to omit this feature increased performance, it also made the machine more vulnerable to crashes from badly written programs than it otherwise might have been.

The problem was somewhat exacerbated by Commodore's initial decision to release documentation relating not only to the OS's underlying software routines, but also to the hardware itself, enabling intrepid programmers to "poke" the hardware directly. While the decision to release this documentation was a popular one, it also contributed to system instability as some programmers lacked the expertise to program at this level. For this reason, when the new AGA chipset was released, Commodore declined to release documentation for it, forcing most programmers to adopt the approved software routines.

Whether lack of memory protection actually made Amigas less reliable than other home PCs of the period is perhaps a matter of opinion. With properly written software, it was always very stable. The OS, however, became more stable, and more hardware independent, with each new OS release.

*NIX

Other, still maintained, operating systems are available for the classic Amiga platform, including Linux and NetBSD. Both require a CPU with MMU such as the 68020 with 68551 or full versions of the 68030, 68040 or 68060. There is a version of Linux for PPC accelerator cards. Debian and Yellow Dog Linux have been made to run on the AmigaOne.

There is an official, older version of OpenBSD. The last Amiga release is 3.2.

The bootblock

However, subsequent Amigas hold Kickstart in a ROM chip. When the machine is started, Kickstart displays a hand holding a disk, inviting the user to insert the Workbench disk (or some other disk). The first two sectors of the disk (512 bytes) are loaded into RAM and control is passed to it.

Most entertainment software, especially during the Kickstart 1.* years, contains a bootblock that loads the rest of the software from the disk and then pass control to it. The game or demo then summarily take control of memory and resources to suit itself, effectively disabling AmigaOS. The GUI can never be invoked. Therefore, most games and demos do not use the operating system at all. Alternatively, it can be said that they install their own custom operating system since any such program must install custom interrupt handlers and so on in order to be of any use.

A floppy disk bootblock may alternatively contain code to load the dos.library (AmigaDOS) and then exit to it, invoking the GUI. Any such disk, no matter what the other contents of the disk, is known as a "DOS disk".

The bootblock became an obvious target for virus writers. Custom bootblock loaders started to be created, which check for the presence of routines pointed by the reboot vectors or hooks in libraries before loading the dos.library, in order to detect viruses. If one installs a DOS bootblock (or a virus surreptitiously installs itself) over those custom bootblocks which don't continue the boot process as normal (such as those present in many games), it will ruin the software.

Emulating other systems

The Amiga is able to emulate other computer platforms which were in its same price range, most notably the IBM PC and the Apple Macintosh. There are also emulators available for many 8 bit systems such as the Commodore 64, Apple II and even the TRS-80. MAME (the arcade machine emulator) is also available for Amigas with PPC accelerator card upgrades.

Amiga software

The Amiga was a primary target for productivity and game development during the late 1980s and early 1990s. Software was often developed for the Amiga and the Atari ST simultaneously, since the ST shared a similar architecture.

All Amiga software is 32 bit on all Amiga models including the original 1985 A1000 and the economy A500. All Amiga CPUs contain 16 general purpose 32-bit registers which is more than a 2006 Pentium has. All Amiga CPUs and software may easily move 32 bits of data from point A to point B in a single machine instruction. 32 bit addressing limited the Amiga 1200 to a maximum of 4096 MB of directly addressable ram. Unfortunately the AmigaOS only truly supports 2048 MB, and older Amigas such as Amiga 500 only have 24 bits of addressing, so they can only directly address 16 MB.

Amiga community

When Commodore went bankrupt in 1994, there was still a very active Amiga community, and it continued to support the platform long after mainstream commercial vendors abandoned it. The most popular Amiga magazine, Amiga Format, continued to publish editions until 2000, some six years after Commodore went bust.

One reason for this loyalty is the multiple strengths of the machine: it has a relatively compact, efficient, multitasking OS, it is relatively easy to program for, software has easy access to the hardware (the base hardware was fixed so software could be coded specifically to the hardware), there is wealth of software, and it was an affordable multimedia machine. The Amiga also allows an unusual degree of control over its environment and functions which makes it both highly configurable and remarkably versatile, so that it can be tailored to a user's unique needs and preferences, much like a PC.

However as time wore on, the hardware was overtaken and as the PC improved in software and hardware the Amiga started to look dated. Despite this, its solid user base continues to produce software and get as much as they possibly can out of the machine. Amiga users manage to squeeze every drop of performance and capability out of the machines, with software and hardware expansions to enhance its capabilities. Even today (2nd qtr. 2006) there is enough demand for expansion hardware to keep some small scale manufacturers in business.

After Commodore went bankrupt

Due to the fierce loyalty of some Amiga fans, the 'scene' continued, many years even after the last original Amiga was sold. Inevitably, though, the PC eventually became the undisputed leading home computing technology, and the console wars also left the CD32 for dead.

The rights to the Amiga platform were successively sold to Escom and later Gateway 2000, but Escom almost immediately went bankrupt itself (due to non-Amiga related problems) and Gateway merely vacillated over what to do with its new acquistion. Finally, an entirely new company called Amiga, Inc. (no relation to the original Amiga Corporation) was founded to manage the Amiga product line. Even though Amiga, Inc. has paid considerably more attention to the Amiga product line than Escom or Gateway 2000, because of the extremely small demand in the mainstream market and limited funds, development has been slow and sales poor.

In 2002, Eyetech in cooperation with Amiga Inc, began selling a small number of AmigaOnes. The "AmigaOne SE" was based on Mai Logic's Teron CX motherboard from 2001 based on the POP (PowerPC Open Platform) design, and development to adapt AmigaOS 4 to this hardware began. The AmigaOne SE was succeeded by AmigaOne XE, which was based on the Teron PX, a newer design with a replaceable CPU module which came in G3 and G4 flavours. In 2004, Eyetech began selling the Micro-A1, based on the Teron Mini, a mini-ITX model with a 750GX G3 CPU. The older Amigas are sometimes referred to as "Classic Amigas" to avoid possible confusion with AmigaOnes.

AmigaOnes are not currently being produced or sold. It is not known whether more will be made.

AmigaOS 4 is still under development, and reports are that it is quite stable and usable. It is hoped that it may be ported to other hardware, possibly another evaluation board, the Pegasos or some kind of Cell based device.

AmigaOS clones

Following Commodore's bankruptcy, two main clones of AmigaOS were developed: MorphOS, which runs on Pegasos machines, and the open source AROS project.

Trivia

• The name amiga is the Spanish and Portuguese word for "female friend", from the Latin amica.
• The name Amiga was used by its developers as a sort of decoy to avoid industrial espionage. When in public places the developers used to talk about the prototype referring to it as "our common Amiga", or using the codename "Lorraine".
• The Amiga was originally intended to be a workstation. When the A1000 was released, it was advertised as a business machine, but it didn't make it, until it began to be used as an videogame computer. (Reference about this can be watched in the Amiga 1000 advertising videos).
• As of 2006, the Amiga still has a very strong user community, particularly outside the United States.
• The TV game show Lingo from 1987 used the Amiga computer for the Lingo cards and the randomly selected five-letter words.
• Amiga's three-finger salute, (CTRL plus the two "Amiga" keys), which reboots the system (but doesn't erase or reload the kickstart software) is actually implemented in hardware, unlike the software-based forms in many OSs. If the OS software doesn't acknowledge the key sequence in a short time (perhaps because the OS has crashed), the keyboard hardware will forcibly reset the CPU. Another kind of three-finger salute (CTRL plus the two "Alt" keys) was introduced with AmigaOS 4.0.
• When AmigaOS crashes, it displays a flashing red box with a mysterious Guru Meditation number — two 32-bit hexadecimal values. The number is usually the 68000 exception number or one of a list of error numbers, and some other piece of information, such as the address of the task that was running at the time the crash was detected. Lists of these errors codes were published regularly by Amiga magazines, so experienced users could use it as a useful reference, and the Guru Meditation system still proves nowadays to give the user more precise information than Blue Screen of Death used in Windows.
• During the Commodore era, machines with "thousands" model numbering were marketed as "quality" machines for business use, while the other machines (A500, A500+, A600, A1200) were "consumer" machines.
• The three most popular low-end models of the Amiga - the 500, 600 and 1200 - each have the name of a B-52's song written on their motherboard. The most widely cited reason for this is the designers having been fans of the band. The motherboard of the 500 says "Rock Lobster", that of the 600 says "June Bug" and that of the 1200 says "Channel Z". No other models have song names on their motherboards.
• The Original Amiga - the A1000 - has the signatures of the development team members moulded into the underside of the plastic top casing.
• Steve Jobs was shown the original prototype for the first Amiga (Amiga 1000) before it had been purchased by Commodore, and said there was "too much hardware". He was working on Macintosh at the time.
• Two of the designers of the original Amiga, RJ Mical and Dave Needle, would later go on to design the Atari Lynx, giving it a framebuffer based display with a blitter very similar to that in the Amiga. The two would also go on to work on the 3DO Interactive Multiplayer.
• When Great Valley Products first released their 68030 accelerator board for the Amiga 2000, it ran Apple's MacOS faster than any real Mac. Apple soon caught up, though.
• In 1999 an announcement was made claiming that a German company named iWin was designing new computers that were compatible with both classic Amigas and IBM PCs. The only source of information about these computers was iWin's own website, which contained some technical circuit diagrams about them. Upon closer inspection, the circuit diagrams were revealed to be completely unrealistic. After a few months, the supposed "iWin Amigas" vanished without a trace, without ever being publicly presented or released into the mass market. The general consensus of the Amiga community is that iWin never had done any real design, but were simply trying to pull a hoax on the eagerly-awaiting Amiga fans. ^*
• Today, many TV stations and broadcast corporations are still using A3000s and A4000s for their real-time video effects.
• Many programs have also been written for creating "fansubs" of foreign films and Japanese animation.
• Many competing products have been created for the Amiga's video capabilities ranging from simple genlocks that allow you to simply switch the RGB overlay feed on and off, to more advanced devices like the Supergen which has faders, and the ultimate expression of the Amiga's native power, NewTek's Video Toaster.
• Other interesting products such as Mandala Interactive System from Vivid Group that use the genlock capability enabled users to do motion tracking and interactivity, 20 years before similar products like the Sony EyeToy for the PlayStation 2 video-game console. These systems were used in science museums to study gesture recognition capabilities and also featured in multimedia artistic exhibitions. See also: Vivid Group Mandala System.
• Due to its ability to genlock, that is, adjust its own screen refresh timing to match the signal from a VCR, the Amiga also has a niche market among biologists analyzing video recordings (kinematic analysis) of organisms in motion at a time when other systems capable of doing similar tasks cost an order of magnitude more.
• Amigas were used in some NASA laboratories to keep track of multiple low orbiting satellites, and were still used in 1999. This is another example of long lifetime reliability of Amiga hardware (and one of its ubiquitous capabilities), as well as its professional use. See also: Reportage: l'Amiga à la NASA; Obligement (Fr).
• Amigas are still used in many theme park installations, mainly at Universal Studios in Hollywood and Florida and Disney World, using Richmond Sound Design's show and sound control software (see the related Wikipedia article on Amiga software).
• Early episodes of the television series Babylon 5 were rendered on Amigas running video toasters ^*.
• In the motion picture Waynes World 2 the character Garth is seen wearing a Video Toaster T-Shirt.
• A Japanese composer by the name of Susumu Hirasawa uses Amiga computers to compose some of his songs.

See also

• AmigaOS
• Amiga software
• Amiga emulation
• Unix Amiga Emulator
• SCA virus
• Gateway 2000
• List of arcade games ports to Amiga

References

• John J. Anderson, "Amiga Lorraine: finally, the 'next generation Atari'?" Creative Computing, April 1984 ^*
• Dave Haynie. "The Amiga A3000+ System Specification". 1991 DevCon Release. July 17, 1991. ^*
• Bagnall, Brian (2005) On the Edge: The Spectacular Rise and Fall of Commodore. Variant Press, ISBN 0973864907.

External links

• Amiga, Inc.
• Amiga on DMOZ
• AmigaWelt.de.ms
• Amiga.org
• Amigaworld.net - Official support forum for the AmigaOne.
• The Big Book of Amiga Hardware - Extensive list of various Amiga peripherals

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