Technical Specifications
The PSP's main microprocessor is a multifunction device named "Allegrex" that includes a 32-bit MIPS32 R4k-based CPU (Little Endian), a Floating Point Unit, and a Vector Floating Point Unit. Additionally, there is a processor block known as "Media Engine" that contains another 32-bit MIPS32 R4k-base CPU, hardware for multimedia decoding (such as H.264), and a programmable DSP dubbed "Virtual Mobile Engine". The secondary CPU present in the Media Engine is functionally equivalent to the primary CPU save for a lack of a VPU. The MIPS CPU cores are globally clocked between 1 and 333 MHz. During the 2005 GDC, Sony revealed that it had capped the PSP's CPU clock speed at 222 MHz for licensed software. Its reasons for doing so are unknown, but are the subject of some speculation. Various homebrew tools enable users to operate at 333 MHz, generally leading to a higher frame rate at the expense of battery life. On June 22, 2007, Sony Computer Entertainment confirmed that the firmware version 3.50 does in fact remove this restriction and allows future games to run at the full 333 MHz speed. It does not affect already-released games.
The system has 32 MiB main RAM in the original PSP and 64 MiB in the PSP 2000 (and subsequent series) and 4 MiB embedded DRAM in all models. The 4 MiB of eDRAM consists of 2 MiB dedicated to the graphics processing unit and 2 MB dedicated to the Media Engine secondary processor. There is no memory management unit for either CPU. No evidence of a TLB has been found. The co-processor that normally manages the TLB-based MMU seems to be a custom effort by Sony and has no integrated memory. Both CPUs contain 16 KiB of two-way set associative instruction cache and data cache respectively. There is additionally 16 KiB of scratchpad RAM which, while faster than main RAM, is not nearly as fast as the integrated cache.
The 166 MHz graphics chip has 2 MiB embedded memory and through its 512 bit interface provides hardware polygon and NURBS rendering, hardware directional lighting, clipping, environment projection and texture mapping, texture compression and tessellation, fogging, alpha blending, depth and stencil tests, vertex blending for morphing effects, and dithering, all in 16 or 24 bit color. The graphics chip also handles image output. Specifications state that the PSP is capable of rendering 33 million flat-shaded polygons per second, with a 664 million pixel per second fill rate.
Read more about this topic: Play Station Portable Hardware
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