Planet Irata: Is the Jaguar Really a 64-bit System?

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Is the Jaguar Really a 64-bit System?

Imagine that, another hot topic pitting Jaguar owners against Jaguar bashers! The question arose because someone noted that the maximum register size in the programmable processors (the 68000, the graphics processor, and the DMA sound processor)is 32-bits.

This argument, however, is bunk. First of all, the 68000 is used as a general control chip. It boots the machine, controls the control pads/joysticks, and other simple housekeeping functions. There is no need for this to be a 64-bit processor. Second, the Jaguar has a 64-bit memory architecture, and the GPU can acess 64-bits of data if required.

According to Jaguar designer John Mathieson,

"Jaguar has a 64-bit memory interface to get a high bandwidth out of cheap DRAM. Where the system needs to be 64-bit then it is 64-bit, so the Object Processor, which takes data from DRAM and builds the display is 64-bit; and the BLiTTER, which does all the 3D rendering, screen clearing, and pixel shuffling, is 64-bit. Where the system does not need to be 64-bit, it isn't. There is no point in a 64-bit address space in a games console! 3D calculations and audio processing do not generally use 64-bit numbers, so there would be no advantage to 64-bit processors for this."

"Jaguar has the data shifting power of a 64-bit system, which is what matters for games, so can reasonably be considered a 64-bit system. But that doesn't mean it has to be 64-bits throughout."

For the record, the opinion of most third party developers and observers is that the Jaguar is indeed a 64-bit system. The emphasis is on the word "system"; while not every component is 64 bits, the Jaguar architecture, as a COMPLETE SYSTEM, is.

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