A 32-bit RISC Microprocessor with DSP Functionality: Rapid Prototyping

Byung In MOON  Dong Ryul RYU  Jong Wook HONG  Tae Young LEE  Sangook MOON  Yong Surk LEE  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E84-A   No.5   pp.1339-1347
Publication Date: 2001/05/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Digital Signal Processing
RISC with DSP functionality,  parallelism between functional units,  latency cycles,  power-saving,  top-down approach,  

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We have designed a 32-bit RISC microprocessor with 16-/32-bit fixed-point DSP functionality. This processor, called YD-RISC, combines both general-purpose microprocessor and digital signal processor (DSP) functionality using the reduced instruction set computer (RISC) design principles. It has functional units for arithmetic operation, digital signal processing (DSP) and memory access. They operate in parallel in order to remove stall cycles after DSP or load/store instructions, which usually need one or more issue latency cycles in addition to the first issue cycle. High performance was achieved with these parallel functional units while adopting a sophisticated five-stage pipeline structure. The pipelined DSP unit can execute one 32-bit multiply-accumulate (MAC) or 16-bit complex multiply instruction every one or two cycles through two 17-b 17-b multipliers and an operand examination logic circuit. Power-saving techniques such as power-down mode and disabling execution blocks allow low power consumption. In the design of this processor, we use logic synthesis and automatic place-and-route. This top-down approach shortens design time, while a high clock frequency is achieved by refining the processor architecture.