Amiga 4000

Commodore Amiga 4000

An Amiga 4000 desktop
Manufacturer	Commodore
Type	Personal computer
Release date	1992; 25 years ago (1992)
Discontinued	1994 (1994)
Operating system	AmigaOS 3.0
CPU	Motorola 68EC030 or 68040 @ 25 MHz
Memory	2-18 MB
Predecessor	Amiga 3000
Successor	Amiga 4000T

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, and the A4000/030 released in April 1993 with a Motorola 68EC030.

The Amiga 4000 introduces the Advanced Graphics Architecture (AGA) chipset with enhanced graphics and continues the A3000's system architecture. However, the SCSI from previous Amigas was replaced by the lower-cost Parallel ATA, but it is possible to add a SCSI controller as an expansion module.

The original A4000 is housed in a beige horizontal desktop box with a separate keyboard. Later, 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 that was intended to expand the "chip RAM" to 8MB. Later, third-party developers created various CPU expansion boards featuring higher rated 68040, 68060 and PowerPC CPUs. Such hardware also typically offers faster and higher capacity RAM (128 MB or greater).

Unlike previous Amiga models, early A4000 machines have the CPU mounted in an expansion board; the motherboard does not have an integrated CPU. Later 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 (cost-reduced) and the surface-mounted CPU is a 68EC030. The cost-reduced models also make use of a non-rechargeable lithium battery for real-time clock battery backup rather than a rechargeable NiCd battery. The NiCd backup battery is one of the most common causes of problems in an aging device that uses one because it has a tendency to eventually leak. The released fluids are somewhat corrosive and can eventually damage the circuitry.