Digital Signal Processors (dsp) Information

Digital Signal Processors (DSP) Information
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Digital signal processors (DSP) are special microprocessors designed for digital signal processing, usually in real-time. DSPs can also be used to perform general-purpose computations; however, they are not optimized for this function. Instead, DSPs use an instruction set architecture (ISA) that is optimized for rapid signal processing.
Important ISA features include deep pipelining to enhance microprocessor performance and the ability to act as a direct memory access device (DMA) for the host environment. Digital signal processors also use Harvard architecture with separate program and data memory. In addition, DSPs use saturation arithmetic so that overflow operations accumulate at the maximum or minimum values that the register can hold instead of wrapping around.
With DSPs, the maximum remains the maximum. By contrast, with many general-purpose CPUs, the sum of the maximum plus one equals the minimum. Most digital signal processors are fixed-point devices because in real-world signal processing, extra precision is not required and there is a large speed benefit. Floating-point DSPs are common in scientific and other applications that require precision. Digital signal processors feature specialized instructions, modulo-addressing in ring buffers, and bit-reversed addressing mode for Fortran function tree (FFT) cross-referencing.
Generally, DSPs are dedicated integrated circuits (ICs); however, DSP functionality can also be realized using field programmable gate array (FPGA) chips. DSPs are used in several classes of computer hardware, including sound cards, modems, telephony boards that handle sound and modem functions, and hardware that handles audio and video compression in real time. 
Specifications
Selecting digital signal processors requires an analysis of performance specifications. DSPs operate with variety of supply voltages and include data buses that range from 8-bit to 256-bit devices. DSPs also vary in terms of clock speed, which is typically expressed in megahertz (MHz) and gigahertz (GHz). Often, integrated on-chip phase-locked loops (PLLs) with clock frequency synthesis capabilities are used to design high-speed internal clocks for data sampling in DSP applications.
Measurements of DSP processing power include million instructions per second (MIPS) and million multiply / accumulates per second (MMACS). For floating-point devices, an additional measurement is million floating-point operations per second (MFLOPS). For all DSPs, the operating current, operating temperature, and power dissipation are also important specifications.