Amiga

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The first Amiga home computer, Commodore-Amiga 1000 (or A1000 for short), was released in 1985 by Commodore. A500 (low-end) and A2000 (high-end) followed in the year 1987. A500 was the most popular Amiga computer.

Generally Amiga was regarded as a game machine. It was also used for commercial entertainment production till mid 1990s (Video editing, 3D graphics rendering etc).

TheAmiga community contributed a lot to a computer subculture known as the Demo Scene. The Demo Scene was more or less a phenomena inherited from Commodore C64 times.

Some technical specifications of A500:

  • Motorola MC68000 (32-bit CISC microprocessor with 16 registers lacking MMU for memory protection and virtual memory)
  • Default operating system AmigaOS 1.3 (having 32-bit pre-emptive multitasking microkernel)
  • 512 kB of general purpose memory by default (sound buffers, graphics buffers and software existed in same memory space)
    • upper limit of 16 MB of memory due to MC68000 limitations
  • OCS/ECS chipset
  • Most multimedia features (sound and graphics) functioned with programmable DMA
  • Graphics capabilities:
    • 50 Hz PAL and 60 Hz NTSC versions available
    • resolutions from 320x256 to 640x512 available
    • X x 256 resolutions were non-interlaced (and so had the full 50/60 Hz vertical refresh rate), and X x 512 resolutions were interlaced (and so effectively had only a 25/30 Hz vertical refresh rate)
    • 32 hardware colours for 320 pixel wide modes and 16 colours for 640 pixel wide modes
    • hardware colours chosen from 4096 colour 12-bit RGB space
    • HAM (hold and modify) mode made possible to display all 4096 simultaneously on the screen
    • framebuffers operated in planar bitfield modes
    • framebuffers were often linear, but not limited to that
    • hardware graphics potential is very hard to explain briefly since it's pretty complicated due to copper co-processor
  • For example, it was possible to use different 32 hardware colours many times during the screen draw.
  • one could have had screen splitted from center to two different screen modes with different 32 colours).
  • 8 separate hardware sprites (used for mouse pointer for example) with 16 pixel width and arbitrary height with 4 colours
    • It was actually possible to have arbitrary width sprites by running sprite hardware with copper co-processor.

Sound capabilities:

  • 4 channel hardware DMA driven stereo output with 8-bit PCM samples and up to 28.1kHz sample rate
  • sample rates and pointers separate for each of 4 DMA channels
  • Possible to emulate 14-bit sounds with hardware DMA by modulating 2 channels with other 2 channels
  • sound dynamics of 8-bits == 48.165 dB

Special features:

  • Blitter (block image transferer had 3 operations: copy, fill and draw lines)
    • copper (3 instruction co-processor running in parallel with main CPU made possible to create special graphics effects with minimal CPU load and intervention)
  • IRQ sharing (like PCI bus)
  • IRQ system had 7 priority levels of interrupts
    • Absolutely no limit on number of interrupts available
    • Resources handled by Autoconfig, very similar to ACPI, resources were not numbered or labelled, just given as amounts and addresses.
  • No specific I/O ports, used memory mapped I/O space separately for each hardware device (thankyou, Jay Miner)

Later Amiga models included:

  • A600, CD-TV
  • A3000 (MC68030 procsessor)
  • AmigaCD32 (MC68020), A1200 (MC680EC20) and A4000 (MC68030/40)

At least the following operating systems are available for Amigas: AmigaOS, Linux and NetBSD

For a long time, Amiga was the most powerful and flexible hardware platform available. The kind of restrictions on other computer systems simply were not present. Amiga could read any format of floppy disk as long as you have the appropriate software, any format of hard disk and even can extract DVD blocks using CD-ROM drives!

Unfortunately, Commodore thought the Amiga was a toaster (and so did Newtek, but that's a different story), so their marketing didn't do the platform justice. Most retail outlets were toy stores. Compatibility with ordinary household television sets was prioritized over professional grade graphics and memory management. Even "amenities" such as a hard drive (on a 500)or a non-interlaced display had to be had from third party vendors. While it was the only multitasking platform in the consumer marketplace for several years, robustness left a lot to be desired, resulting in frequent "Guru Meditations".

In spite of being sold so short, Amiga was originally supported by such prestigious software titles as AutoCAD, WordPerfect and Lattice C.

Different Amiga emulators exist for variety of operating systems. For example UNIX and Microsoft Windows operating systems: