Monday, February 13, 2006



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For the A-road in England, see A500 road.

The A500, also known as the Amiga 500, was the first "low-end" Commodore Amiga 16-bit multimedia home/personal computer model. It was released in 1987, at the same time as the high-end A2000, and competed directly against the Atari 520ST.

An Amiga 500 computer system, with 1084S RGB monitor and A1010 floppy disk drive.
An Amiga 500 computer system, with 1084S RGB monitor and A1010 floppy disk drive.

Technical specifications:

  • Motorola 68000 (32-bit CISC microprocessor with 16 registers lacking MMU for memory protection and virtual memory) running at 7.16 MHz (NTSC version), 7.09 MHz (PAL version)
  • Default operating system AmigaOS 1.2 or 1.3 (having 32-bit pre-emptive multitasking microkernel) depending on the revision
  • 512 KB of Chip RAM by default (sound buffers, graphics buffers and software existed in the same memory space)
    • upper limit of 16 MB of memory due to MC68000 limitations (24-bit external address bus)
  • OCS/ECS chipset
  • 50 Hz PAL and 60 Hz NTSC TV output by default versions available; 50/60Hz mode switchable by software in later revisions
  • software-switchable low-pass audio filter (power LED shows filter status, darker when off)
  • IRQ sharing (like the PCI bus)
  • IRQ system had 7 priority levels of interrupts
    • 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, instead using memory mapped I/O space separately for each hardware device (thanks to Jay Miner)

Amiga 500 was used a lot for gaming, and there were a variety of Atari-style game controllers that could be used. One of the most popular ones was TAC-2, The Totally Accurate Controller mk2 by Suncom.

                List of Commodore microcomputers

MOS Technology 6502-based (8-bit):   MOS/CBM KIM-1 | PET/CBM | CBM-II (aka B/P series) | VIC-20/VC-20 | C64 | SX-64 | C16 & 116 | Plus/4 | C128

M68K-based (16/32-bit):   Amiga 1000 | Amiga 500 | Amiga 2000 | Amiga 500+ | Amiga 2500 | Amiga 3000, UX, T | Amiga 600 | Amiga 1200 | Amiga 4000

The A500 designation was also used on an internal Acorn Archimedes development machine [1].

The A500 often featured the words "The B-52s Rock Lobster" written on the motherboard, in reference to the popular song of that time period.