Amiga 500

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Commodore Amiga 500


Type	Home computer
Released	1987
Discontinued	1991
Processor	Motorola 68000 @ 7.16 MHz 7.09 MHz (PAL)
Memory	512 KiB (9.5 MiB maximum)
OS	Amiga OS 1.2~1.3

The Amiga 500, also known as the A500, was the first "low-end" Commodore Amiga 16/32-bit multimedia home/personal computer. It was announced at the winter Consumer Electronics Show in January 1987, at the same time as the high-end A2000, and competed directly against the Atari 520ST. The A500 was released in mid 1987 at the price of US $595.95 without monitor.

The original A500 proved to be Commodore's best-selling Amiga model [1], enjoying particular success in Europe. Although popular with hobbyists, arguably its most widespread use was as a gaming machine, where its advanced graphics and sound were of significant benefit. In October 1989, the A500 was bundled with the Batman Pack[2], which was sold in the United Kingdom.

In late 1991, an enhanced model known as the A500 Plus replaced the standard A500 in some markets.

The A500 series was discontinued altogether in mid-1992. The similarly-specified and priced A600 was marketed as its replacement, although this new machine had originally been intended as a much cheaper budget model, the A300. In late 1992, Commodore released the "next-generation" A1200, a machine closer in concept to the original A500, but featuring significant technical improvements. Despite this, neither the A1200 nor the A600 replicated the commercial success of its predecessor.

1 Technical specifications
- 1.1 Connectors
- 1.2 Expansions
2 Trivia

[edit] Technical specifications

Motorola 68000 microprocessor running at 7.15909 MHz in the NTSC version or 7.09379 MHz in the PAL version. While this was a 32-bit chip internally, it had a 16-bit data bus and 24-bit address bus, providing a maximum of 16 MiB addressable space.
OCS chipset. Later revisions of the chipset made PAL/NTSC mode switchable in software.
- Graphics could be of arbitrary dimensions, resolution and colour depth, even on the same screen.
- Without using overscan, the graphics could be 320 or 640 pixels wide by 200/256 or 400/512 pixels tall.
- Planar graphics were used, with up to 5 bitplanes (4 in hires), allowing 2, 4, 8, 16 and 32 colour screens, from a palette of 4096 colours. Two special graphics modes where also included: Extra HalfBrite, which used a 6th bitplane as a mask that halved the brightness of any colour seen, and Hold And Modify (HAM), which allowed all 4096 colours on screen at once.
- Sound was 4 hardware-mixed channels of 8-bit sound at up to 28 kHz. The hardware channels had independent volumes (65 levels) and sampling rates, and mixed down to two fully left and fully right stereo outputs. A software controllable low-pass audio filter was also included.
512 KiB of Chip RAM.
AmigaOS 1.2 or 1.3
One double-density floppy disk drive was included, which was completely programmable and thus could read 720 KiB IBM PC disks, 880 KiB standard Amiga disks, and up to 984 KiB with custom formatting (such as Klaus Deppich's diskspare.device).
Built in keyboard.
A two-button mouse was included.

[edit] Connectors

50 Hz PAL and 60 Hz NTSC analogue RGB video output, provided on an Amiga-specific video connector. This could also be genlocked to an external video signal. An RF adapter was bundled with the machine to provide output on regular televisions.
The analogue RGB output on a DB-23 pin can drive a signal at 15.75KHz HSync for standard Amiga video modes. This is not compatible with most VGA monitors. A Multisync monitor is required.
Stereo phono connectors for audio.
A standard RS-232 serial port.
A parallel port.
A floppy drive port, for daisy-chaining up to 3 extra floppy disk drives.
Two Atari DE9 sockets for joysticks or mice.

[edit] Expansions

Expansion ports were limited to a side expansion port and a trapdoor expansion on the underside of the machine. The casing could also be opened up (voiding the warranty), all chips were socketed rather than surface-mounted, so they could be replaced by hand.
The CPU could be upgraded to a 68010 directly or to a 68020, 68030 or 68040 via the side expansion slot.
The Chip RAM could be upgraded to 1 MiB directly on the motherboard, provided a Fat Agnus chip was also installed to support it.
Likewise, all the custom chips could be upgraded to the ECS chipset.
512 KiB of "Slow RAM" or "Trapdoor RAM" could be added via the trapdoor expansion. Such upgrades usually also included a battery-backed clock.
Up to 8 MiB of "Fast RAM" could be added via the side expansion slot.
Hard drive and other peripherals could be added via the side expansion slot.
Several companies provided combined CPU, memory and hard drive upgrades, or provided chainable expansions, as there was only one side expansion slot.
Expansions were configured automatically by AutoConfig software, so multiple pieces of hardware did not conflict with each other.

[edit] Trivia

The A500 designation was also used on an internal Acorn Archimedes development machine [3].
The A500 featured the words "B52/ROCK LOBSTER" written on the motherboard, in reference to a The B-52's popular song of that time period.

v • d • e 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
Motorola 68000-based (16-bit/32-bit)	Amiga 1000 • Amiga 500 • Amiga 2000 • Amiga 2500 • Amiga 1500 • Amiga CDTV • Amiga 3000 • Amiga 3000UX • Amiga 3000T • Amiga 500+ • Amiga 600 • Amiga 1200 • Amiga 4000 • Amiga 4000T