Chip RAM By Model
Most stock Amiga systems were equipped with chip RAM only and shipped with between 256 kB and 2 MB.
Model | Stock chip RAM | Maximum chip RAM | Width |
---|---|---|---|
Amiga 1000 | 256 kiB | 512 kiB | 16-bit |
Amiga 500, Amiga 2000 | 512 kiB - 1 MiB | 512 kiB - 1 MiB | 16-bit |
CDTV, Amiga 500 Plus, Amiga 600 | 1 MiB | 2 MiB | 16-bit |
Amiga 3000 | 1 MiB | 2 MiB | 32-bit |
Amiga 1200, Amiga 4000, Amiga CD32 | 2 MiB | 2 MiB | 32-bit |
The shared RAM data bus is 16-bit on OCS and ECS systems. The later AGA systems use a 32-bit data bus controlled by the Alice coprocessor (replacing Agnus) and 32-bit RAM. The memory clock runs at double the rate on AGA systems. As a result, chipset RAM bandwidth is increased fourfold compared to the earlier 16-bit design. The ECS-based A3000 also has 32-bit shared RAM but access is only 32 bit for CPU operations; the chipset remained 16-bit.
The maximum amount of chip RAM is dependent on the Agnus/Alice version. The original Agnus chip fitted to the A1000 and early A2000 systems is a 48-pin DIP package able to address 512 kiB of chip RAM. Subsequent versions of the Agnus are in an 84-pin PLCC package (either socketed or surface-mounted). All models, except the A1000, are upgradable to 2 MiB of chip RAM. The A500, and later versions of the A2000, with hardware modification can accommodate 1 MiB by installing a later revision Agnus chip (8732A); late-production machines usually already contained that chip, so that only jumper modifications were necessary. Likewise, 2 MB can be installed by fitting an 8372B Agnus and extra memory.
The maximum amount of chip RAM in any model is 2 MiB. The Amiga 4000 motherboard includes a non-functional jumper that claims to accommodate 8 MiB of chip RAM - regardless of its position, the system only recognizes 2 MiB due to the limitations of the Alice chip. However, the software emulator, UAE, can emulate an Amiga system with up to 8 MiB of chip RAM.
Read more about this topic: Amiga Chip RAM
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