AGA

AGA was developed in the early 1990s by Commodore Corporation. It was first introduced in August 1992 . Later, in October of the same year, it was introduced for the entry-level model A1200 .

In the US, the chipset was originally called AA ( Advanced Architecture , there is also a version of the Advanced Amiga decryption). Subsequently, for Europe , it was changed to AGA to reflect the significant improvements in the graphic subsystem (rather than the system as a whole), as well as to avoid problems with the brand. [one]

The AGA chipset was developed in 1992 by Commodore Corporation and significantly expanded the ability to output color images on the Amiga 1200 and Amiga 4000 . Computers built on the basis of AGA were able to display up to 262,144 colors from a 24-bit palette. The new chipset has retained software compatibility: programs correctly written for old chipsets ( OCS and ECS ) are fully functional on AGA.

The idea of HAM ( Hold and Modify ) was further developed. In particular, the new HAM8 mode appeared. Unlike the previous version of HAM , 8 bits of memory were allocated for modifying the pixel color. This made it possible to display up to 262,144 colors simultaneously. Also, as in HAM , in the HAM8 mode, the color of each pixel was either selected from a predefined palette or obtained by modifying one of the RGB components of the adjacent (left) pixel. The HAM8 technique allowed computer users to play in real-time specially prepared video clips in improved (compared to previous versions) quality. The disadvantages of the HAM mode were the complexity of its use for vector graphics, as well as the possibility of specific distortions when playing back some video clips and static images.

The use of AGA chipset modes (in particular, HAM8 ) reduced the memory requirements for storing graphics, as well as the capacity and speed of a hard disk when playing animations from it. To output video clips that are comparable in quality to the analog standard VHS , the usual IDE hard disk drive was enough. In this regard, in the 90s, Amiga 1200 and Amiga 4000 computers with the AGA chipset were widely used in low-budget television studios. They were used as title machines, freeze frame storages, as well as stations for the production and reproduction of computer graphics.

The AGA chipset was used in the following Amiga computer models:

• Amiga 1200
• Amiga 4000
• Amiga 4000T
• Amiga CD32

• Algorithm Hold and Modify (HAM)
• OCS Chipset on the classic Amiga
• ECS Chipset Classic Amiga
• AAA Chipset

• Brief description of AGA on Amiga history guide (The Amiga AGA Chipset)
• AGA Chipset Programming Guide (How to Code the Amiga - AGA Chipset)