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This paper presents a new design method of the reverse (residue-to-binary) converter for the flexible 3-moduli residue number system (RNS) set { 2 k , 2 n - 1 , 2 n + 1 } , where k and n are a pair of arbitrary integers ≥ 2 . The basic equation of the reverse converter is formulated in two alternative forms, each of which consists of two separate parts: one depending on input variables of the converter, and the other being a single constant. The constant can be either added inside the reverse converter or shifted out to the residue datapath channels, in most cases at no hardware cost or extra delay. From the set of basic functions, which are essentially different than those of the only two known general converters proposed for this moduli set, four versions of a converter can be designed for any pair of k and n. Experimental results obtained using the commercial 65-nm low-power design kit and industrial synthesis tools for all dynamic ranges from 8 to 40 bits suggest that, compared to the state-of-the-art designs, at least one version of the newly proposed converters is superior w.r.t. delay, power consumption, and area, for all dynamic ranges considered. The savings for the best versions (these with constants moved to the datapath channels) are up to 12.7% for the area and from 2.5% to 14% (5.8 % on average) for the delay, while the power consumption is reduced up to 23.2% (5.6% on average). [ABSTRACT FROM AUTHOR]

In this paper, we propose a new approach to implement a reliable softcore processor on SRAM-based FPGAs, which can mitigate radiation-induced temporary faults (single-event upsets (SEUs)) at moderate cost. A new Enhanced Lockstep scheme built using a pair of MicroBlaze cores is proposed and implemented on Xilinx Virtex-5 FPGA. Unlike the basic lockstep scheme, ours allows to detect and eliminate its internal temporary configuration upsets without interrupting normal functioning. Faults are detected and eliminated using a Configuration Engine built on the basis of the PicoBlaze core which, to avoid a single point of failure, is implemented as fault-tolerant using triple modular redundancy (TMR). A softcore processor can recover from configuration upsets through partial reconfiguration combined with roll-forward recovery. SEUs affecting logic which are significantly less likely than those affecting configuration are handled by checkpointing and rollback. Finally, to handle permanent faults, the tiling technique is also proposed. The new Enhanced Lockstep scheme requires significantly shorter error recovery time compared to conventional lockstep scheme and uses significantly smaller number of slices compared to known TMR-based design (although at the cost of longer error recovery time). The efficiency of the proposed approach was validated through fault injection experiments. [ABSTRACT FROM AUTHOR]