A1000

The A1000, or Commodore Amiga 1000, was Commodore's initial Amiga multimedia home/personal computer, released in 1985. Before follow-up models A500 and A2000 were released in 1987, the A1000 was just called the (Commodore) Amiga.

Technical specifications:

• Motorola 68000 (32-bit CISC microprocessor with 16 registers lacking MMU for memory protection and virtual memory).
• Default operating system AmigaOS 1.0 or 1.1 (having 32-bit pre-emptive multitasking microkernel) depending on the revision; loaded from the Kickstart floppy disk at power-on
• 256 KB of Chip RAM by default (sound buffers, graphics buffers and software existed in same memory space)
  • upper limit of 16 MB of memory due to MC68000 limitations (24-bit external address bus)
• OCS chipset
• 50 Hz PAL and 60 Hz NTSC TV output by default versions available
  • 50/60Hz mode switchable by software, although switching a PAL Amiga to NTSC mode produces a 60Hz PAL display, and vice versa (this would usually suffice for software relying on a particular format)
• hardware-switchable low-pass audio filter (cut/join a track, many people built switches); software-switchable on later models
• 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