AMIGA
\ɐmˈiːɡə], \ɐmˈiːɡə], \ɐ_m_ˈiː_ɡ_ə]\
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A range of home computers first released byCommodore Business Machines in early 1985 (though they didnot design the original - see below). Amigas were popular forgames, video processing, and multimedia. One notablefeature is a hardware blitter for speeding up graphicsoperations on whole areas of the screen.The Amiga was originally called the Lorraine, and wasdeveloped by a company named "Amiga" or "Amiga, Inc.", fundedby some doctors to produce a killer game machine. After theUS game machine market collapsed, the Amiga company sold somejoysticks but no Lorraines or any other computer. Theyeventually floundered and looked for a buyer.Commodore at that time bought the (mostly complete) Amigamachine, infused some money, and pushed it through the finalstages of development in a hurry. Commodore released itsometime[?] in 1985.Most components within the machine were known by nicknames.The coprocessor commonly called the "Copper" is in fact the"Video Timing Coprocessor" and is split between two chips:the instruction fetch and execute units are in the "Agnus"chip, and the pixel timing circuits are in the "Denise" chip(A for address, D for data)."Agnus" and "Denise" were responsible for effects timed to thereal-time position of the video scan, such as midscreenpalette changes, sprite multiplying, and resolutionchanges. Different versions (in order) were: "Agnus" (couldonly address 512K of video RAM), "Fat Agnus" (in a PLCCpackage, could access 1MB of video RAM), "Super Agnus" (slightly upgraded "Fat Agnus"). "Agnus" and "Fat Agnus" camein PAL and NTSC versions, "Super Agnus" came in oneversion, jumper selectable for PAL or NTSC. "Agnus" wasreplaced by "Alice" in the A4000 and A1200, which allowed formore DMA channels and higher bus bandwidth."Denise" outputs binary video data (3*4 bits) to the "Vidiot".The "Vidiot" is a hybrid that combines and amplifies the12-bit video data from "Denise" into RGB to the monitor.Other chips were "Amber" (a "flicker fixer", used in the A3000and Commodore display enhancer for the A2000), "Gary" (I/O,addressing, G for glue logic), "Buster" (the buscontroller, which replaced "Gary" in the A2000), "Buster II" (for handling the Zorro II/III cards in the A3000, which meantthat "Gary" was back again), "Ramsey" (The RAM controller),"DMAC" (The DMA controller chip for the WD33C93 SCSI adaptorused in the A3000 and on the A2091/A2092 SCSI adaptor card forthe A2000; and to control the CD-ROM in the CDTV), and"Paula" (Peripheral, Audio, UART, interrupt Lines, andbus Arbiter).There were several Amiga chipsets: the "Old Chipset" (OCS),the "Enhanced Chipset" (ECS), and AGA. OCS included"Paula", "Gary", "Denise", and "Agnus".ECS had the same "Paula", "Gary", "Agnus" (could address 2MBof Chip RAM), "Super Denise" (upgraded to support "Agnus" sothat a few new screen modes were available). With theintroduction of the Amiga A600 "Gary" was replaced with"Gayle" (though the chipset was still called ECS). "Gayle"provided a number of improvments but the main one was supportfor the A600's PCMCIA port.The AGA chipset had "Agnus" with twice the speed and a 24-bitpalette, maximum displayable: 8 bits (256 colours), althoughthe famous "HAM" (Hold And Modify) trick allows pictures of256,000 colours to be displayed. AGA's "Paula" and "Gayle"were unchanged but AGA "Denise" supported AGA "Agnus"'s newscreen modes. Unfortunately, even AGA "Paula" did not supportHigh Density floppy disk drives. (The Amiga 4000, though,did support high density drives.) In order to use a highdensity disk drive Amiga HD floppy drives spin at half therotational speed thus halving the data rate to "Paula".Commodore Business Machines went bankrupt on 1994-04-29,the German company Escom AG bought the rights to the Amigaon 1995-04-21 and the Commodore Amiga became the EscomAmiga. In April 1996 Escom were reported to be making theAmiga range again but they too fell on hard times andGateway 2000 (now called Gateway) bought the Amiga brandon 1997-05-15.Gateway licensed the Amiga operating system to a Germanhardware company called Phase 5 on 1998-03-09. Thefollowing day, Phase 5 announced the introduction of afour-processor PowerPC based Amiga clone called the"pre\box". Since then, it has been announced that thenew operating system will be a version of QNX.On 1998-06-25, a company called Access Innovations Ltdannounced plans (http://micktinker.co.uk/aaplus.html) tobuild a new Amiga chip set, the AA+, based partly on the AGAchips but with new fully 32-bit functional core and 16-bit AGAhardware register emulation for backward compatibility.The new core promised improved memory access and video displayDMA.By the end of 2000, Amiga development was under the control ofa [new?] company called Amiga, Inc.. As well as continuingdevelopment of AmigaOS (version 3.9 released in December2000), their "Digital Environment" is a virtual machine formultiple platforms conforming to the ZICO specification.As of 2000, it ran on MIPS, ARM, PPC, and x86processors. (http://amiga.com/).Amiga Web Directory (http://cucug.org/amiga.html).amiCrawler (http://amicrawler.com/).Newsgroups: news:comp.binaries.amiga,news:comp.sources.amiga, news:comp.sys.amiga,news:comp.sys.amiga.advocacy,news:comp.sys.amiga.announce,news:comp.sys.amiga.applications,news:comp.sys.amiga.audio, news:comp.sys.amiga.datacomm,news:comp.sys.amiga.emulations, news:comp.sys.amiga.games,news:comp.sys.amiga.graphics,news:comp.sys.amiga.hardware,news:comp.sys.amiga.introduction,news:comp.sys.amiga.marketplace, news:comp.sys.amiga.misc,news:comp.sys.amiga.multimedia,news:comp.sys.amiga.programmer,news:comp.sys.amiga.reviews, news:comp.sys.amiga.tech,news:comp.sys.amiga.telecomm, news:comp.Unix.amiga.See aminet, Amoeba, bomb, exec, gronk, gurumeditation, Intuition, sidecar, slap on the side,Vulcan nerve pinch.
By Denis Howe
Word of the day
SQ10,643
- A serotonin antagonist with limited antihistaminic, anticholinergic, and immunosuppressive activity.