TheAmiga 2000, orA2000, is apersonal computerreleased byCommodorein March 1987.It was introduced as a "big box" expandable variant of theAmiga 1000but quickly redesigned to share most of its electronic components with the contemporaryAmiga 500for cost reduction. Expansion capabilities include two 3.5"drive bays(one of which is used by the includedfloppy drive) and one 5.25" bay that can be used by a 5.25" floppy drive (forIBM PCcompatibility), ahard drive, orCD-ROMonce they became available.
The Amiga 2000 is the first Amiga model that allows expansion cards to be added internally.SCSI host adapters,memory cards,CPU cards,network cards,graphics cards,serial portcards, andPC compatibilitycards were available, and multiple expansions can be used simultaneously without requiring an expansion cage like the Amiga 1000 does. Not only does the Amiga 2000 include fiveZorro IIcard slots, the motherboard also has fourPC ISAslots, two of which are inline with Zorro II slots for use with the A2088 bridgeboard, which addsIBM PC XTcompatibility to the A2000.
TheEnhanced Chip Set(ECS) is the second generation of theAmigacomputer's chipset, offering minor improvements over theoriginal chipset(OCS) design. ECS was introduced in 1990 with the launch of theAmiga 3000. Amigas produced from 1990 onwards featured a mix of OCS and ECS chips, such as later versions of theAmiga 500and theCommodore CDTV. Other ECS models were theAmiga 500+in 1991 and lastly theAmiga 600in 1992.
Notable improvements were theSuper Agnusand theHiResDenisechips. The sound and floppy controller chip,Paula, remained unchanged from the OCS design. Super Agnus supports 2MBofChip RAM, whereas the originalAgnus/Fat Agnusand subsequentFatter Agnuscan address 512KBand 1 MB, respectively. The ECS Denise chip offersProductivity(640×480 non-interlaced) andSuperHiRes(1280×200 or 1280×256) display modes (also available in interlaced mode), which are however limited to only 4 on-screen colors. Essentially, a 35nspixel mode was added plus the ability to run arbitrary horizontal and vertical scan rates. This made other display modes possible, but only the aforementioned modes were supported originally out of the box. For example, the Linux Amiga framebuffer device driver allows the use of several other display modes. Other improvements were the ability of the blitter to copy regions larger than 1024×1024 pixels in one operation and the ability to display sprites in border regions (outside of any display window where bitplanes are shown). ECS also allows software switching between 60Hz and 50Hz video modes.