Original chip set
The OCS (abbreviation for O riginal C hip S et) was the chipset of the early Amiga models. It was installed in the Amiga 500 , Amiga 1000 , Amiga 1500 and Amiga 2000 . It consisted of the chips Agnus, Denise and Paula. This division into three chips was due to the limited production possibilities of the 1980s; in principle, the chips are to be understood as a unit.
The OCS has noticeable similarities in the architecture as well as in the division of functions with the core hardware of the Atari 8-bit computer series , which also consists of three chips, ANTIC, GTIA and POKEY , which was launched in 1979. Both chipsets were designed by Jay Miner .
OCS was followed by ECS , AGA , AAA .
Agnus
The name Agnus is derived from the word address generator: A dress G e n erator U nit s .
The chip is responsible for controlling the chip RAM . Among other things, he gets the graphic data from it, which is then displayed by the Denise chip (see below).
Agnus also processes the various video synchronization signals and contains and controls the two coprocessors Blitter and Copper .
Agnus provides the system with a powerful DMA unit which, on the one hand, fetches the video and sound data from the chip RAM and, on the other hand, can also copy data within the chip RAM and process ( blend ) it, but also Can generate data, namely when drawing lines and filling areas with the blitter.
The video data that Agnus fetches from the chip RAM via DMA includes the pixel data, palette and sprite data as well as the copper lists.
Denise
The name is derived from the English words display encoder .
The chip controls the graphics output and displays the sprites and BOBs , among other things .
In the prototype stage of the Amiga this chip was still called Daphne.
Versions
- 8362R6 252126-01 (A500, A1000, A2000)
- 8362R8 252126-02 (A500, A2000, CDTV)
- 8373 390433-01 / -02 Super Denise / Hires Denise (A500 +, A2000, A3000)
- 8373 391061-01 / 391081-01 (PLCC, A600)
- in Advanced Graphics Architecture Denise was Lisa replaced
Paula
The name Paula is derived from the English words peripheral and audio .
The chip controls the following tasks in the Amiga:
- Input and output control for floppy disk drives
- Sound output (D / A converter)
- Query of the analog inputs / outputs
- UART for the serial interface
This chip was also used in the later Amiga chipsets and was the reason why the later Amiga models were no longer up-to-date in the areas covered by Paula. (Limited data transfer rate for floppy disk drives, so that HD drives have to run at half speed; sound output audibly worse than CD quality.)
In the prototype stage of the Amiga this chip was still called Portia (for Ports and Audio).
Individual evidence
- ↑ Agnus 8370 on cbmmuseum.kuto.de
- ↑ Amiga Custom Chip Agnus (English)
- ↑ Denise 8362 on cbmmuseum.kuto.de
- ↑ Amiga Custom Chip Denise (English)
- ↑ Paula 8364 on cbmmuseum.kuto.de
- ↑ Amiga Custom Chip Paula (English)
