  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 introduced the advanced graphics architecture (aga) chipset with enhanced graphics and continued the a3000's system architecture. however, the scsi peripheral interface was replaced by lower cost ide. the a4000 is housed in a white desktop box with a separate keyboard. later commodore released an expanded tower version called the a4000t. ==technical information== === processor and ram === the stock a4000 shipped with either a motorola 68ec030 or 68040 cpu, 2&nbsp;mb of amiga chip ram and up to 16&nbsp;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&nbsp;mb or greater). ===a4000-cr version=== 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&nbsp;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 made 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 a4000 because it has a tendency to eventually leak. the released fluids are somewhat corrosive and can eventually damage
Amiga Computer-related_introductions_in_1992