Abstract: Embedded systems are characterized by small size, high speed and minimum power requirements. Apart from satisfying these characteristics, the embedded products need to meet some design metrics viz. time to prototype, time to market, Non Recurring Engineering (NRE) Cost. So as to meet some of these requirements and to speed up the process of hardware-software co-design, soft CPU cores are made available by different manufacturers. This has simplified the job of an embedded product designer to a great extent. Soft-core processors play a vital role due to their ease of usage. Soft-core processors have advantages like reduced cost, flexibility, platform independence and greater immunity to obsolescence over their hard-core counterparts. The soft CPUs come with different features. Some soft CPUs are open source while others are proprietary; some are of RISC category while others are of CISC type. Based on product development requirements, an appropriate soft CPU core could be selected. This paper presents review on features of a few soft core processors, which are popular in the embedded development market.

Keywords: Time to Prototype, Time to market, NRE Cost, open- source, soft-core processors, RISC, CISC.