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. It was also used in early PlayStation 3 models sold in Japan and North America (Model Numbers CECHAxx & CECHBxx), to provide PlayStation 2 game support. Mass production of the Emotion Engine began in 1999 and ended in late 2012 with the discontinuation of the PlayStation 2.
The Emotion Engine consists of eight separate "units", each performing a specific task, integrated onto the same die. These units are: a CPU core, two Vector Processing Units (VPU), a 10 channel DMA unit, a memory controller, and an Image Processing Unit (IPU). There are three interfaces: an input output interface to the I/O processor, a graphics interface (GIF) to the graphics synthesizer, and a memory interface to the system memory.
The CPU core is tightly coupled to the first VPU, VPU0. Together, they are responsible for executing game code and high-level modeling computations. The second VPU, VPU1, is dedicated to geometry-transformations and lighting and operates independently, parallel to the CPU core, controlled by microcode. VPU0, when not utilized, can also be used for geometry-transformations. Display lists generated by CPU/VPU0 and VPU1 are sent to the GIF, which prioritizes them before dispatching them to the Graphics Synthesizer for rendering.
The CPU core is a two-way superscalar in-order RISC processor. Based on the MIPS R5900, it implements the MIPS-III instruction set architecture (ISA) and much of MIPS-IV, in addition to a custom instruction set developed by Sony which operated on 128-bit wide groups of either 32-bit, 16-bit, or 8-bit integers in single instruction multiple data (SIMD) fashion (i.e. four 32-bit integers could be added to four others using a single instruction). Instructions defined include: add, subtract, multiply, divide, min/max, shift, logical, leading-zero count, 128-bit load/store and 256-bit to 128-bit funnel shift in addition to some not described by Sony for competitive reasons. 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. For comparison, 128-bit wide registers and SIMD instructions had been present in the 32-bit x86 architecture since 1999, with the introduction of SSE. However the internal data paths were 128bit wide, and its processors were capable of operating on 4x32bit quantities in parallel in single registers.
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