Amiga 500 Plus

Commodore Amiga 500 Plus

Release date	1991
Discontinued	1992
Media	880 kB floppy disks
Operating system	AmigaOS v2.04
CPU	Motorola 68000 @ 7.16 MHz (NTSC) 7.09 MHz (PAL)
Memory	1 MB (9.5 MB maximum)
Graphics	640 x 256, 6 bpp @ 25 fps
Sound	4x 8-bit channels at max 28 kHz with 6-bit volume in stereo.
Predecessor	Amiga 500
Successor	Amiga 600

The Commodore Amiga 500 Plus^[1] (often A500 Plus or simply A500+) is an enhanced version of the original Amiga 500 computer. It was notable for introducing new versions of Kickstart and Workbench, and for some minor improvements in the custom chips, known as the Enhanced Chip Set (or ECS).

Introduction

The A500+ was released in several markets (including many European countries), but was never sold officially in the U.S.^[2]

Although officially introduced in 1992, some Amiga 500 Plus units had already been sold (masquerading as Amiga 500 models, and with no prior announcement) during late 1991. It has been speculated that Commodore had already sold out the remaining stocks of Amiga 500s, before the run up to the profitable Christmas sales period. In order to make enough A500s before Christmas, Commodore used stocks of the new 8A revision motherboards destined for the A500+. Many users were unaware that they were purchasing anything other than a standard Amiga 500. Although the Amiga 500+ was an improvement to the Amiga 500, it was minor. It was discontinued and replaced by the Amiga 600 in summer 1992, making it the shortest lived Amiga model

Reason for design

Commodore created the A500+ for a couple of reasons. The first was cost reduction; minor changes were made to the motherboard to make it cheaper to produce. It was also so that Commodore could introduce the new version of the Amiga Operating system, 2.04.

Compatibility problems

Due to the new Kickstart, quite a few popular games (such as SWIV, Treasure Island Dizzy and Lotus Esprit Turbo Challenge) failed to work on the Amiga 500+, and some people took them back to dealers demanding an original Kickstart 1.3 Amiga 500. This problem was solved by third-parties who produced Kickstart ROM switching boards, that could allow the Amiga 500+ to be downgraded to Kickstart 1.2 or 1.3. It also encouraged game developers to use better programming habits, which was important since Commodore already had plans for the introduction of the next-generation Amiga 1200 computer. A program, Relokick, was also released (and included with an issue of CU Amiga) which loaded a Kickstart 1.3 ROM image into memory and booted the machine into Kickstart 1.3, allowing incompatible software to run.

Technical specifications

• Motorola 68000 CPU running at 7.09 MHz (PAL) / 7.16 MHz (NTSC), like its predecessor.
• 1 MB of Chip RAM (Very early versions came with 512 KiB)
• Kickstart 2.04 (v37.175)
• Workbench 37.67 (release 2.04)
• Built in battery backed RTC (Real Time Clock)
• Full ECS Chipset including new version of the Agnus chip and Denise chip.

See also

• Amiga models and variants

Footnotes

1. ^ The case badge reads "Commodore A-500 Plus"[1], with "Amiga" embossed elsewhere. However, as with the Amiga range in general, Commodore do not appear to have been overly concerned with naming consistency, the packaging being one example of this.
2. ^ [2]