The Amiga is a family of personal computers introduced by Commodore in 1985. The original model was part of a wave of 16- and 32-bit computers that featured 256 KB or more of RAM, mouse-based GUIs, improved graphics and audio over 8-bit systems; this wave included the Atari ST—released the same year—Apple's Macintosh, the Apple IIGS. Based on the Motorola 68000 microprocessor, the Amiga differed from its contemporaries through the inclusion of custom hardware to accelerate graphics and sound, including sprites and a blitter, a pre-emptive multitasking operating system called AmigaOS; the Amiga 1000 was released in July 1985, but a series of production problems kept it from becoming available until early 1986. The best selling model, the Amiga 500, was introduced in 1987 and became one of the leading home computers of the late 1980s and early 1990s with four to six million sold; the A3000, introduced in 1990, started the second generation of Amiga systems, followed by the A500+, the A600 in March 1992.
As the third generation, the A1200 and the A4000 were released in late 1992. The platform became popular for gaming and programming demos, it found a prominent role in the desktop video, video production, show control business, leading to video editing systems such as the Video Toaster. The Amiga's native ability to play back multiple digital sound samples made it a popular platform for early tracker music software; the powerful processor and ability to access several megabytes of memory enabled the development of several 3D rendering packages, including LightWave 3D, Aladdin4D, TurboSilver and Traces, a predecessor to Blender. Although early Commodore advertisements attempt to cast the computer as an all-purpose business machine when outfitted with the Amiga Sidecar PC compatibility add-on, the Amiga was most commercially successful as a home computer, with a wide range of games and creative software. Poor marketing and the failure of the models to repeat the technological advances of the first systems meant that the Amiga lost its market share to competing platforms, such as the fourth generation game consoles and the dropping prices of IBM PC compatibles which gained 256-color VGA graphics in 1987.
Commodore went bankrupt in April 1994 after the Amiga CD32 model failed in the marketplace. Since the demise of Commodore, various groups have marketed successors to the original Amiga line, including Genesi, Eyetech, ACube Systems Srl and A-EON Technology. AmigaOS has influenced replacements and compatible systems such as MorphOS, AmigaOS 4 and AROS. "The Amiga was so far ahead of its time that nobody—including Commodore's marketing department—could articulate what it was all about. Today, it's obvious the Amiga was the first multimedia computer, but in those days it was derided as a game machine because few people grasped the importance of advanced graphics and video. Nine years vendors are still struggling to make systems that work like 1985 Amigas." Jay Miner joined Atari in the 1970s to develop custom integrated circuits, led development of the Atari 2600's TIA. As soon as its development was complete, the team began developing a much more sophisticated set of chips, CTIA, ANTIC and POKEY, that formed the basis of the Atari 8-bit family.
With the 8-bit line's launch in 1979, the team once again started looking at a next generation chipset. Nolan Bushnell had sold the company to Warner Communications in 1978, the new management was much more interested in the existing lines than development of new products that might cut into their sales. Miner wanted to start work with the new Motorola 68000, but management was only interested in another 6502 based system. Miner left the company, for a time, the industry. In 1979, Larry Kaplan founded Activision. In 1982, Kaplan was approached by a number of investors. Kaplan hired Miner to run the hardware side of the newly formed company, "Hi-Toro"; the system was code-named "Lorraine" in keeping with Miner's policy of giving systems female names, in this case the company president's wife, Lorraine Morse. When Kaplan left the company late in 1982, Miner was promoted to head engineer and the company relaunched as Amiga Corporation. A breadboard prototype was completed by late 1983, shown at the January 1984 Consumer Electronics Show.
At the time, the operating system was not ready, so the machine was demonstrated with the Boing Ball demo. A further developed version of the system was demonstrated at the June 1984 CES and shown to many companies in hopes of garnering further funding, but found little interest in a market, in the final stages of the North American video game crash of 1983. In March, Atari expressed a tepid interest in Lorraine for its potential use in a games console or home computer tentatively known as the 1850XLD, but the talks were progressing and Amiga was running out of money. A temporary arrangement in June led to a $500,000 loan from Atari to Amiga to keep the company going; the terms required the loan to be repaid at the end of the month, otherwise Amiga would forfeit the Lorraine design to Atari. During 1983, Atari lost over $1 million a week, due to the combined effects of the crash and the ongoing price war in the home computer market. By the end of the year, Warner was desperate to sell the company.
In January 1984, Jack Tramiel resigned from Commodore due to internal battles over the future direction of the company. A number of Commodore employees followed him to Tramiel Technology; this included a number of the senior technical staff, where they began development of a 68000-based machine of the
A blitter is a circuit, sometimes as a coprocessor or a logic block on a microprocessor, dedicated to the rapid movement and modification of data within a computer's memory. A blitter can copy large quantities of data from one memory area to another quickly, in parallel with the CPU, while freeing up the CPU's more complex capabilities for other operations. A typical use for a blitter is the movement of a bitmap, such as windows and fonts in a graphical user interface or images and backgrounds in a 2D video game; the name comes from the bit blit operation of the 1973 Xerox Alto, which stands for bit-block transfer. A blit operation is more than a memory copy, because it can involve data that's not byte aligned, handling transparent pixels, various ways of combining the source and destination data. Blitters have been superseded by programmable graphics processing units. In early computers with raster-graphics output, the frame buffer was held in main memory and updated via software running on the CPU.
For many simple graphics routines, like compositing a smaller image into a larger one or drawing a filled rectangle, large amounts of memory had to be manipulated, many CPU cycles were spent fetching and decoding instructions for short repetitive loops of load/store instructions. For CPUs without caches, the bus requirement for instructions was as significant as data. Further, as a single byte held between 2 and 8 pixels, the data was not aligned for the CPU, so extra shifting and masking operations were required. 1973: The Xerox Alto, where the term bit blit originated, has a bit block transfer instruction implemented in microcode, making it much faster than the same operation written on the CPU. The microcode was implemented by Dan Ingalls.1982: The Robotron: 2084 arcade game from Williams Electronics includes two blitter chips which allow the game to have up to 80 moving objects. Performance was measured at 910 KB/second; the blitter operates on 4-bit pixels where color 0 is transparent, allowing for non-rectangular shapes.
Williams used the same blitters in other games from the time period, including Sinistar and Joust.1984: The MS-DOS compatible Mindset contains a custom VLSI chip to move rectangular sections of a bitmap. The hardware handles transparency and eight modes for combining the destination data; the Mindset was claimed to have graphics up to 50x faster than PCs of the time, but the system was not successful. 1985: Commodore's Amiga launches with a blitter co-processor. The first US patent filing to use the term blitter was "Personal computer apparatus for block transfer of bit-mapped image data," assigned to Commodore-Amiga, Inc; the blitter performs a 4 operand boolean operation. 1986: The TMS34010 is a general purpose 32-bit processor with additional blitter-like instructions for manipulating bitmap data. It is optimized for cases that take extra processing on the CPU, such as handling transparent pixels, working with non-byte aligned data, converting between bit depths; the TMS34010 served as both CPU and GPU for a number of arcade games in the late 1980s and early 1990s, including Hard Drivin', Smash TV, Mortal Kombat, NBA Jam, as well as finding use in PC graphics accelerator boards in the 1990s.
1986: The Intel 82786 is a programmable graphics processor which includes a BIT_BLT instruction to move rectangular sections of bitmaps.1987: The IBM 8514/A display adapter, introduced with the IBM Personal System/2 computers in April 1987, includes bit block transfer hardware. 1987: Atari Corporation introduces a blitter co-processor, stylized as the BLiTTER chip, on the Atari Mega ST 2 computer. It was supported on most machines. 1989: The short-lived Atari Transputer Workstation contains blitter hardware as part of its "Blossom" video system.1993: The last console produced by Atari Corporation, the Jaguar has blitter hardware as part of the custom "Tom" chip. A computer program puts information into certain registers describing what memory transfer needs to be completed and the logical operations to perform on the data; the CPU triggers the blitter to begin operating. The CPU is free for other processing while the blitter is working, though the blit running in parallel uses memory bandwidth.
To copy data with transparent portions—such as sprites—a color can be designated to be ignored during the blit. On other systems, a second 1 bit per pixel image may be used as a "mask" to indicate which pixels to transfer and which to leave untouched; the mask operates like a stencil. The logical operation is destination:= OR sprite. Hardware sprites are small bitmaps that can be positioned independently, composited together with the background on-the-fly by the video chip, so no actual modification of the frame buffer occurs. Sprite systems are more efficient for moving graphics requiring 1/3 the memory cycles because only image data—not CPU instructions—need to be fetched, with the subsequent compositing happening on-chip; the downside of sprites is a limit of moving graphics per scanline, which can range from three to eight to higher for 16-bit arcade hardware and consoles, the inability to update a permanent bitmap. Direct Memory Access
Original Chip Set
The Original Chip Set is a chipset used in the earliest Commodore Amiga computers and defined the Amiga's graphics and sound capabilities. It was succeeded by the improved Enhanced Chip Set and improved Advanced Graphics Architecture; the original chipset appeared in Amiga models built between 1985 and 1990: the Amiga 1000, Amiga 2000, Amiga CDTV, Amiga 500. The chipset which gave the Amiga its unique graphics features consists of three main "custom" chips. Both the original chipset and the enhanced chipset were manufactured using NMOS logic technology by Commodore's chip manufacturing subsidiary, MOS Technology. According to Jay Miner, the OCS chipset was fabricated in 5 µm manufacturing process while AGA Lisa was implemented in 1.5 µm process. All three custom chips were packaged in 48-pin DIPs. Agnus is the central chip in the design, it controls all access to chip RAM from both the central 68000 processor and the other custom chips, using a complicated priority system. Agnus includes sub-components known as the Copper.
The original Agnus can address 512 KB of chip RAM. Revisions, dubbed'Fat Agnus', added 512 KB pseudo-fast RAM, which for ECS was changed to 1 MB and subsequently to 2 MB chip RAM. Denise is the main video processor. Without using overscan, the Amiga's graphics display is 320 or 640 pixels wide by 200 or 256 pixels tall. Denise supports interlacing, which doubles the vertical resolution, at the cost of intrusive flickering on typical monitors of that era. Planar bitmap graphics are used, which splits the individual bits per pixel into separate areas of memory, called bitplanes. In normal operation, Denise allows between five bitplanes, giving two to 32 unique colors; these colors are selected from a palette of 4096 colors. A 6th bitplane is available for two special video modes: Hold-And-Modify mode. Denise supports eight sprites, single pixel scrolling, a "dual-playfield" mode. Denise handles mouse and digital joystick input. Paula is the audio chip, with four independent hardware-mixed 8-bit PCM sound channels, each of which supports 65 volume levels and waveform output rates from 20 samples per second to 29,000 samples per second.
Paula handles interrupts and various I/O functions including the floppy disk drive, the serial port, analog joysticks. There are many similarities – both in overall functionality and in the division of functionality into the three component chips – between the OCS chipset and the much earlier and simpler chipset of the Atari 8-bit family of home computers, consisting of the ANTIC, GTIA and POKEY chips; the Agnus chip is in overall control of the entire chipset's operation. All operations are synchronised to the position of the video beam; this includes access to the built-in RAM, known as chip RAM. Both the central 68000 processor and other members of the chipset have to arbitrate for access to chip RAM via Agnus. In computing architecture terms, this is Direct Memory Access. Agnus has a complex and priority-based memory access policy that attempts to best coordinate requests for memory access among competing resources. For example, bitplane data fetches are prioritized over blitter transfers as the immediate display of frame buffer data is considered more important than the processing of memory by the blitter.
Agnus attempts to order accesses in such a way so as to overlap CPU bus cycles with DMA cycles. As the original 68000 processor in Amigas tended only to access memory on every second available memory cycle, Agnus operates a system where "odd" memory access cycles are allocated first and as needed to time-critical custom chip DMA while any remaining cycles are available to the CPU, thus the CPU does not get locked out of memory access and does not appear to slow down. However, non-time-critical custom chip access, such as blitter transfers, can use up any spare odd or cycles and, if the "BLITHOG" flag is set, Agnus can lock out the cycles from the CPU in deference to the blitter. Agnus's timings are measured in "color clocks" of 280 ns; this is equivalent to four high resolution pixels. Like Denise, these timings were designed for display on household TVs, can be synchronized to an external clock source; the blitter is a sub-component of Agnus. "Blit" is shorthand for "block image transfer" or bit blit.
The blitter is a parallel memory transfer and logic operation unit. It has three modes of operation: copying blocks of filling blocks and line drawing; the blitter allows the rapid copying of video memory, meaning that the CPU can be freed for other tasks. The blitter was used for drawing and redrawing graphics images on the screen, called "bobs", short for "blitter objects"; the blitter's block copying mode takes zero to three data sources in memory, called A, B and C, performs a programmable boolean function on the data sources and writes the result to a destination area, D. Any of these four areas can overlap; the blitter runs either from the start of the block to the end, known as "ascending" mode, or in reverse, "descending" mode. Blocks are "rectangular".
The Amiga 2000, or A2000, is a personal computer released by Commodore in March 1987. It was introduced as a "big box" expandable variant of the Amiga 1000 but redesigned to share most of its electronic components with the contemporary Amiga 500 for cost reduction. Expansion capabilities include two 3.5" drive bays and one 5.25" bay that can be used by a 5.25" floppy drive, a hard drive, or CD-ROM once they became available. The Amiga 2000 is the first Amiga model. SCSI host adapters, memory cards, CPU cards, network cards, graphics cards, serial port cards, PC compatibility cards were available, multiple expansions can be used without requiring an expansion cage like the Amiga 1000 does. Not only does the Amiga 2000 include five Zorro II card slots, the motherboard has four PC ISA slots, two of which are inline with Zorro II slots for use with the A2088 bridgeboard, which adds IBM PC XT compatibility to the A2000; the Amiga 2000 was the most versatile and expandable Amiga computer until the Amiga 3000T was introduced four years later.
Aimed at the high-end market, the original Europe-only model adds a Zorro II backplane, implemented in programmable logic, to the custom Amiga chipset used in the Amiga 1000. Improved models have redesigned hardware using the more integrated A500 chipset, with the addition of a gate-array called "Buster", which integrates the Zorro subsystem; this enables hand-off of the system control to a coprocessor slot device, implements the full video slot for add-on video devices. Like the earlier model, the Amiga 1000, most IBM PC compatibles of the era, but unlike the Amiga 500, the A2000 comes in a desktop case with a separate keyboard; the case is taller than the A1000 to accommodate expansion cards, two 3.5" and one 5.25" drive bays. The A2000's case lacks the "keyboard garage" of the Amiga 1000 but has space for five Zorro II expansion slots, two 16-bit and two 8-bit ISA slots, a CPU upgrade slot and a video slot. Unlike the A1000, the A2000's motherboard includes a battery-backed real-time clock.
The Amiga 2000 offers graphics capabilities exceeded among its contemporaries only by the Macintosh II, which sold for about twice the price of a comparably-outfitted Amiga 2000 additionally equipped with the IBM PC Compatible bridgeboard and 5.25" floppy disk drive. Like the A1000, the A2000 was sold only by specialty computer dealers, it was announced at a price of 1495 USDThe A2000 was succeeded by the Amiga 3000 in 1990. The 3000 features fewer options for internal expansion than the 2000 models, so Commodore supplemented the Amiga 3000 with the Amiga 3000T in 1991; the Amiga 2000 was designed with an open architecture. Commodore's engineers believed that the company would be unsuccessful in matching the rate of system obsolesce and replacement common in the PC industry, with new models every year or so. Commodore's approach was to build a single system architecture. Commodore was so successful at this that Info magazine judged that the A2000 would not become obsolete "until well after the turn of the century" at the earliest.
The final design was the result of an internal battle within Commodore, which pitted the USA division, who wanted to build a system more like the Amiga 3000, against the German division, fresh from the successful introduction of the first Commodore PC-compatible systems and planned to include this capability in the Amiga 2000 from the start. The bottom-line practicality of the German design won out, the final A2000 shipped with not only Zorro II slots, but a complement of PC standard ISA slots; this architecture was subject to major revisions. The "B2000-CR" motherboard was the most common, it was designed by Dave Haynie and Terry Fisher, while an A2000 variant, was a redesign of the Amiga 1000 motherboard incorporating some Amiga 500 technological advances to achieve the "CR": Cost Reduction. The original Amiga 2000 shipped with just a single floppy drive for storage; this was followed up early by the Amiga 2000/HD, which bundled an Amiga 2090 hard drive controller and a SCSI-based hard drive.
In 1988, Commodore shipped the Amiga 2500/20, which added the Amiga 2620 CPU card to the CPU slot, a 14.3 MHz 68020, a 68881 FPU, a 68851 MMU to the A2000, along with 2 MB of 32-bit-wide memory. The A2000's original 68000 CPU remained installed on the motherboard of these machines, but is not used. In 1989 this model was replaced by the Amiga 2500/30, which added an Amiga 2630 CPU card: 25 MHz 68030 and the 68882 FPU with up to 4 MB of 32-bit memory; the A2630 card can take a memory expansion daughter card, capable of supporting up to 64 MB of additional memory. Commodore never released one. In 1990, Commodore UK sold a variant of the A2000, the A1500, for £999; the model designation was not sanctioned by Commodore International. The A1500 shipped with dual floppy drives, 1 MB of ChipRAM as standard. Initial units came with Kickstart 1.3, though the Original Chipset onboard includes a Agnus revision allowing the 1MB of ChipRAM. Early machines were bundled with a Commodore 1084SD1 monitor. Machines came with the ECS chipset and AmigaOS 2.04.
The second floppy drive replaces the hard disk drive. The A1500 has no hard disk drive as standard. A1500s are convertible into A2000/HDs by addition of a hard disk controller, simply peeling off the A1500 label revealing the A2
The Commodore Amiga 3000UX is a model of the Amiga computer family, released with Amiga Unix, a full port of AT&T Unix System V Release 4, installed along with AmigaOS. The system is otherwise equivalent to the standard A3000, once a right-click initiates a boot to Kickstart. At one point, Sun Microsystems approached Commodore-Amiga, Inc. with the offer to produce the A3000UX under license as a low- to mid-range alternative to their high-end Sun workstations. That this offer was declined was one of the many management decisions that led to the popular belief that the Amiga platform would have been a real success story but for Commodore management, it is possible that Commodore repurposed A3000UX machines for standard AmigaOS, as some standard A3000 models have been found with labeling suggesting they were to be sold as A3000UX machines. Amiga models and variants
The CDTV is a home multimedia entertainment and video game console – convertible into a full-fledged personal computer by the addition of optional peripherals – developed by Commodore International and launched in April 1991. The CDTV is a Commodore Amiga 500 home computer with a CD-ROM drive and remote control. With the optional keyboard and floppy disk drive, it gained the functionality of the regular Amiga. Commodore marketed the machine as an all-in-one multimedia appliance; as such, it targeted the same market as the Philips CD-i. The expected market for multimedia appliances did not materialize, neither machine met with any real commercial success. Though the CDTV was based on Amiga hardware, it was marketed as a CDTV, with the Amiga name omitted from product branding. Commodore announced the CDTV at the summer 1990 Consumer Electronics Show in Chicago, promising to release it before the end of the year with 100 software titles; the product debuted in North America in March 1991 and in the UK.
It was advertised at £ 499 for remote control and two software titles. The device was released in the United States for $999. In 1990 Computer Gaming World stated that Commodore had a poor reputation among consumers and developers, citing "abysmal record of customer and technical support in the past"; the company chose Amiga-enthusiast magazines as its chief advertising channel, but the Amiga community on the whole avoided the CDTV in the expectation of an add-on CD-ROM drive for the Amiga, which came in the form of the A570. This further hurt sales of the CDTV, as an A570-equipped A500 was electronically the same as a CDTV and could run CDTV software, so there was little motivation for an Amiga owner to buy a CDTV. Commodore would rectify this with CDTV's successor, the A1200-based Amiga CD32, by adding the Akiko chip, enabling developers to produce CD32 games that were playable only on the CD32. However, Nolan Bushnell, one of the chief endorsers of the CDTV, argued the system's high price alone was enough to explain its market failure: "... it's difficult to sell significant numbers of anything at more than $500....
I felt. I thought, and I can tell you that the number of units that we sold in the U. S. at $800 you could put in your eye and not draw tears."The CDTV was supplied with AmigaOS 1.3, rather than the more advanced and user-friendly 2.0 release, launched at around the same time. Notably, the CDXL motion video format was developed for the CDTV, making it one of the earliest consumer systems to allow video playback directly from CD-ROM. By 1994 Computer Gaming World described the CDTV as a "fiasco" for Commodore. Though the company developed an improved and cost-reduced CDTV-II, it was never released. Commodore discontinued the CDTV in 1993 with the launch of the Amiga CD32, which again was based on Amiga hardware but explicitly targeted the games market; the CDTV was intended as a media appliance rather than as a mainstream personal computer. As such, its housing had dimensions and styling that were comparable to most household stereo system components of the period, it came with an infrared remote control.
It was sold without a keyboard or a mouse. The CDTV was based on the same technology as earlier Amiga systems, but featured a single-speed CD-ROM drive and no floppy disk drive as standard. ^ North American model ^ UK model ^ European model The CDTV is compatible with many Amiga peripherals from the same period. In addition, official CDTV peripherals and upgrades included: Wireless infrared mouse Wireless trackball Black styled keyboard SCSI controller providing both an internal and external SCSI connector for hard disk drives and other SCSI devices External black styled hard disk drive External black styled floppy disk drive Proprietary memory cards with a capacity of 64 or 256 kB allowing storage of game scores and progress Genlocks for NTSC or PAL to overlay video signal with a secondary video source CDTV: CDTV unit and remote control/gamepad Pro pack: CDTV unit, remote control/gamepad, keyboard and floppy disk drive, along with Almathera CDPD Public domain software compilation on CD-ROM Philips' CD-i Pioneer's LaserActive Tandy Video Information System NEC PC Engine with Super CD-ROM expansion Nintendo's SNES Sega Mega Drive with CD-ROM expansion The 3DO Company's 3DO Interactive Multiplayer Amiga CD32 Amiga models and variants
The Commodore Amiga 4000, or A4000, is the successor of the A2000 and A3000 computers. There are two models, the A4000/040 released in October 1992 with a Motorola 68040 CPU, the A4000/030 released in April 1993 with a Motorola 68EC030; the Amiga 4000 system design was similar to the A3000's, but introduced the Advanced Graphics Architecture chipset with enhanced graphics. The SCSI system from previous Amigas was replaced by the lower-cost Parallel ATA; the original A4000 is housed in a beige horizontal desktop box with a separate keyboard. Commodore released an expanded tower version called the A4000T; the stock A4000 shipped with either a Motorola 68EC030 or 68040 CPU, 2 MB of Amiga Chip RAM and up to 16 MB of additional RAM in 32-bit SIMMs. There is a non-functional jumper, intended to expand the "chip RAM" to 8MB. Third-party developers created various CPU expansion boards featuring higher rated 68040, 68060 and PowerPC CPUs; such hardware typically offers faster and higher capacity RAM. Unlike previous Amiga models, early A4000 machines have the CPU mounted in an expansion board.
Revisions of the A4000 have the CPU and 2 MB RAM surface-mounted on the motherboard in an effort to reduce costs. These machines are known as the A4000-CR and the surface-mounted CPU is a 68EC030; the cost-reduced models make use of a non-rechargeable lithium battery for real-time clock battery backup rather than a rechargeable NiCad battery. The NiCad backup battery is one of the most common causes of problems in an aging device that uses one because it has a tendency to leak; the released fluids are somewhat corrosive and can damage the circuitry. The A4000 is the first Amiga model to have shipped with Commodore's third-generation Amiga chipset, the 32-bit Advanced Graphics Architecture; as the name implies, AGA introduces improved graphical abilities a palette expanded from 12-bit color depth to 24-bit and new 128, 256 and 262,144 color modes. Unlike earlier Amiga chipsets, all color modes are available at all display resolutions. AGA improves sprite capacity and graphics performance; the on-board sound hardware remains identical to that of the original Amiga chipset, four DMA-driven 8-bit PCM channels, with two channels for the left speaker and two for the right.
The A4000 has a number of Amiga-specific connectors including two DE-9 ports for joysticks and light pens, a standard 25-pin RS-232 serial port and a 25-pin Centronics parallel port. As a result, at launch the A4000 was compatible with many existing Amiga peripherals, such as, MIDI devices, serial modems and sound samplers. Like the just-earlier Amiga model, the 3000, the A4000 has four internal 32-bit Zorro III expansion slots; this expansion bus allows the use of devices which comply with the AutoConfig standard, such as graphic cards, audio cards, network cards, SCSI controllers, even USB controllers. One of the most notable hardware items of the era is the NewTek Video Toaster system which became popular in the 1990s for amateur and commercial desktop video production of standard-definition broadcast quality video, consisting of tools for video switching, chroma keying, character generation and image manipulation; the three ISA slots can be activated by use of a bridgeboard, which connects the Zorro and ISA buses.
Such bridgeboards feature on-board IBM-PC-compatible hardware, including Intel 80286, 80386, or 80486 microprocessors allowing emulation of an entire IBM-PC system in hardware. Compatible ISA cards may be installed into the two remaining ISA slots. In an effort to offer modern expansion options third-party developers created replacement expansion boards for the A4000 which provide PCI slots allowing use of higher performance and available PCI hardware, such as graphic and network cards; the A4000 shipped with AmigaOS 3.0, consisting of Workbench 3.0 and Kickstart 3.0, which together provide a single-user multi-tasking operating system and support for the built-in hardware. Following release of AmigaOS 3.1 it became possible to upgrade the A4000 by installing compatible Kickstart 3.1 ROM chips. The AmigaOS 3.5 and 3.9 releases were software-only updates requiring Kickstart 3.1. AmigaOS 4, a PowerPC-native release of the operating system, can be used with the A4000 provided a CyberStorm PPC board is installed.
MorphOS, an alternative Amiga-compatible operating system, can be used with this hardware. Variants of platform-independent operating systems such as Linux and BSD can be used with the A4000. Amiga models and variants