Emotion Engine

The Emotion Engine is a central processing unit developed and manufactured by Sony Computer Entertainment and Toshiba for use in the PlayStation 2 video game console.

The second VPU, VPU1, is dedicated to geometry-transformations and lighting and operates independently, parallel to the CPU core, controlled by microcode.

Contrary to some misconceptions, these SIMD capabilities did not amount to the processor being "128-bit", as neither the memory addresses nor the integers themselves were 128-bit, only the shared SIMD/integer registers.

However the internal data paths were 128-bit wide, and its processors were capable of operating on 4x32bit quantities in parallel in single registers.

Both the instruction and data caches are virtually indexed and physically tagged while the scratchpad RAM exists in a separate memory space.

The majority of the Emotion Engine's floating point performance is provided by two vector processing units (VPU), designated VPU0 and VPU1.

Each VPU features 32 128-bit vector SIMD registers (holding 4D vector data), 16 16-bit fixed-point registers, four floating point multiply-accumulate (FMAC) units, a floating point divide (FDIV) unit and a local data memory.

[5] Communications between the MIPS core, the two VPUs, GIF, memory controller and other units is handled by a 128-bit wide internal data bus running at half the clock frequency of the Emotion Engine but, to offer greater bandwidth, there is also a 128-bit dedicated path between the CPU and VPU0 and a 128-bit dedicated path between VPU1 and GIF.

The Emotion Engine interfaces directly to the Graphics Synthesizer via the GIF with a dedicated 64-bit, 150 MHz bus that has a maximum theoretical bandwidth of 1.2 GB/s.

The Emotion Engine contained 13.5 million metal–oxide–semiconductor (MOS) transistors,[7] on an integrated circuit (IC) die measuring 240 mm2.

However, the second revisions of the PlayStation 3 lacked a physical Emotion Engine in order to lower costs, performing all of its functions using software emulation performed by the Cell Broadband Processor, coupled with a hardware Graphics Synthesizer still present to achieve PlayStation 2 backwards compatibility.