Commodore 500/500+

Met de Amiga zette Commodore in 1987 opnieuw een fantastische computer op de markt. Met het 4 kanalen stereo geluid kon je deze machine perfect voor muziek gebruiken. Ook de grafische kant was op dat moment vooruitstrevend.

De machine was redelijk compact en was zeer krachtig. Al snel was er een harde schijf op de markt en ook niet veel later een CD-rom drive. Deze kunnen aangesloten worden op de poort aan de zijkant van de Amiga 500 zonder verdere aanpassingen of software. De processor is de zogeheten 68000 deze communiceert met de rest van de computer via de address bus, data bus en control lines. De drie custom chips staan niet in direct contact met de 68000. Alleen wanneer de 68000 een bus cycle start voor één van de custom chips of de display RAM zal de control chip constateren of deze beschikbaar is. De 3 custom chips zijn zeer snel in de grafische voorstelling en de audio data. Custom chip 1 heeft als bijnaam Fat Agnus, de andere heten Denise (video) en Paula (Sound & I/O). 

Technische specificaties: Motorola MC68000, 7,16 MHZ, OS 1.2, 1.3, Chipset OCS, 4Channel Stereo-Sound, ChipRAM 512KB, Interfaces voor Memory-uitbreiding, Accelerator-Card, Harddisk. Serieele-, Parallele-, RGB-, muis- en Joystickpoort.
 
In 1991 kwam de Amiga 500/Plus op de markt en deze werd na zes maanden alweer opgevolgd door de Amiga 600. Hij leek van buiten op de “orginele Amiga 500” maar binnenin was toch wel degelijk een hoop veranderd. De machine had nu standaard 1mb RAM, een Enhanced Chip Set (ECS) en bevatte de nieuwe workbench versie 2.0 waardoor de blauwe interface van workbench 1.3 kwam te vervallen voor een wat rustiger grijs en blauw. Ook kunnen de files zonder icon nu gewoon bekeken en bewerkt worden. 
 
Commodore had another success at the homecomputer market with Amiga 500. The 500 was relatively compact had a lot of power and was soon accompanied by hard drive and other “side-car” upgrades, including the Amiga 570 CD-ROM drive in 1992. The 68000 is the CPU of the system. All other resources are under software control via control data issued from it. All 3 custom chips have control registers that are written by the 68000. The 68000 communicates with the rest of the computer via its address bus, data bus and control lines. The 3 custom chips do not reside directly on the 68000 buses. When the 68000 starts a bus cycle that is intended for the custom chips or the display RAM, the bust controll chip detects whether or not the display RAM buses are available. The 3 custom chips provide very fast manipulation of graphics and audio data in the display RAM. Fat Agnus, custom chip #1, contains 25 dedicated purpose DMA counters (the other ones are called: Denise (video) and Paula (Sound & I/O). The 3 chips have control registers which are usually loaded by the 68000. However, Fat Agnus also has the capability of loading control registers in the other 2 custom chips. When Fat Agnus perfoms a bus cycle, it outputs a code on the Register Address Bus telling the other 2 chips the nature of the bus cycle. This is necessary because many of the bus cycles provide data to or from the other 2 chips, thus they must cooperate appropriately.
Technical specifications: Motorola MC68000, 7,16 MHZ, OS 1.2, 1.3, Chipset OCS, 4Channel Stereo-Sound, ChipRAM 512KB, 880KB Floppy Interfaces for Memory-Expansion, Accelerator-Card, Harddisk etc. Serial-, Parallel-, RGB-, Mouse- and Joystickport.
 
In 1991, Commodore released the Amiga 500/Plus and is widely known as the shortest-lived Amiga ever, lasting only 6 months until it was phased out by the A600. This was yet another of Commodores secrets with many people opening their Amigas at Christmas expecting to find a A500 only to find something much better. It looked physically similar to the A500, but updated it with 1mb of RAM, Enhanced Chip Set (ECS) and Workbench 2.0 which turned the horrible blue interface of workbench 1.3 into a much more lovely grey and blue. It also allowed the user to see files that did not have icons without resorting to the CLI and put among other things the FastFileSystem into ROM (Kickstart) allowing you to boot from FFS disks containing 880k of data.