Commodore Amiga 2000

Type	Personal computer
Release date	1987
Discontinued	1991
Operating system	Amiga OS 1.2/1.3 or 2.0
CPU	Motorola 68000 @ 7.16 MHz (NTSC) 7.09 MHz (PAL)
Memory	1 MB (9 MB maximum)
Predecessor	Amiga 1000
Successor	Amiga 3000

The Amiga 2000, or A2000, is a personal computer released by Commodore in March, 1987.^[1][2][3] It is the successor to the Amiga 1000.

Features [link]

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. Later improved models have redesigned hardware using the more highly integrated A500 chipset, with the additional of a gate-array called "Buster", which integrates the Zorro subsystem.^[4]. This also enabled handoff of the system control to a coprocessor slot device, and implemented the full video slot for add-on video devices.

Like the earlier Amiga 1000 and most typical PCs, and unlike the Amiga 500, the A2000 came in a desktop case with a separate keyboard. The case was taller than the A1000 to accommodate expansion cards, two 3.5" and one 5.25" drive bays and, like a traditional PC, it lacks the "keyboard garage" of the Amiga 1000. The A2000 has space for five Zorro II proprietary expansion slots, two 16-bit and two 8-bit ISA slots, a CPU upgrade slot, a video slot, and includes a battery-backed real-time clock.^[5]

The A2000 offered graphics capabilities only exceeded among its contemporaries by the Macintosh II, a system which sold for about five times the Amiga's price. Also like the A1000, the A2000 was sold only by specialty computer dealers.

The A2000 was largely succeeded by the Amiga 3000 in 1990.

Variants [link]

The Amiga 2000 was always designed as a system platform. Commodore's engineers knew that Commodore would be unsuccessful in matching the rate of system obsolesce and replacement practiced by many in the PC industry, new models every year or so. Thus, Commodore's approach was to build a single system architecture that could span different models.

This architecture was subject to major revisions. The "B2000-CR" motherboard was the most common, showing up as the first major revision. It was designed by Dave Haynie and Terry Fisher (whose names are printed on the board) and, 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 fairly 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 14.3MHz 68020, a 68881 FPU, and a 68851 MMU to the A2000, along with 2MB of 32-bit-wide memory. In 1989, this model was replaced by the Amiga 2500/30, which added an Amiga 2630 CPU card: 25MHz 68030 and the 68882 FPU with up to 4MB of 32-bit memory. The A2630 card could also take a memory expansion daughter card, capable of supporting up to 64MB of additional memory. Commodore built an in-house prototype of this, but never released one.

Somewhat later, Commodore UK sold a variant of the A2000, the A1500, though that model designation was not officially sanctioned by Commodore International. The A1500 shipped with dual floppy drives, and 1 MB of RAM as standard, along with the ECS chipset and AmigaOS 2.04.

Technical information [link]

The majority of A2000 systems shipped with Commodore's Original Chip Set and 1 MB of RAM (512 kB of "chip" RAM and 512 kB additional RAM) and either AmigaOS 1.2 or 1.3. Later revisions shipped with the improved Enhanced Chip Set, 1 MB "chip" RAM and AmigaOS 2.0.^[6]

The A2000 shipped with a Motorola 68000 CPU, running at 7.16 MHz (NTSC) or 7.09 MHz (PAL). The CPU can be upgraded to a 68010 by direct replacement. Official and third-party expansion boards, which fit in the CPU expansion slot, feature 68020, 68030, 68040 or 68060 microprocessors. Such upgrades may also accommodate additional RAM, FPUs, MMUs and even SCSI controllers.

Memory capacity varies according to the hardware revision. Certain revisions of the A2000 can be upgraded to accommodate 1 MB of chip RAM by installing an 8732A Agnus chip. Likewise, 2 MB can be accommodated by fitting an 8372B Agnus chip and adding extra memory. There is a practical limit of 8 MB of additional RAM without the use of a CPU expansion card, due to the 68000's 24-bit address bus.

The A2000 brought a new capability to the Amiga line, the Zorro II bus. This expansion bus allows installation of compatible hardware through the AutoConfig standard, such as, graphic, sound and network cards and Parallel ATA, SCSI and USB controllers.

The ISA slots can be activated by use of a "bridgeboard", which connects the Zorro II and ISA buses. Such bridgeboards typically feature on-board IBM PC Compatible hardware, including Intel 80286, 80386 or 80486 microprocessors allowing emulation of an entire IBM-PC system in hardware. The remaining ISA slots allow can then be used with industry standard hardware of the era, such as, network cards, graphics cards and hard drive controllers. In some A2000 models, the two 8-bit ISA slots can also be upgraded to 16-bit by fitting extension edge connectors.

The video slot presented clocks, all 12-bits of digital video, Genlock signals, and some control lines for use to add-on cards. This allowed use of dedicated genlocks, display de-interlacers, and video switching and effects systems such as NewTek's Video Toaster.

Specifications [link]

Notes [link]

1. ^{^} Model A (revision 3.0-4.0), 1986
2. ^{^} Model B (revision 4.1-5.0), 1986
3. ^{^} Model C (revision 6.0-6.5), 1991

See also [link]

• Amiga models and variants

References [link]

External links [link]

• amigahistory.co.uk/a2000 – History of the Amiga 2000.

Wikimedia Commons has media related to: Amiga 2000