KANATA, ONT. With its announcement this week of its Tsi920 chip, Tundra Semiconductor Corp. is expanding beyond its traditional realm of bus interface silicon into the communications fray. The multiport packet-manager IC provides the link between a DSP subsystem and a host processor on a board to optimize overall throughput.
In its first iteration, the chip supports Texas Instruments C54x DSPs on one side and a Motorola PowerQuicc communications processor on the other, but vice president Richard O'Connor said that other DSPs and processors are on the company's road map.
The Tsi920 is designed to eliminate today's "bandwidth mismatch" between communications processors and DSP arrays on a system board, according to O'Connor. The register-based host ports on DSPs are inherently "inefficient and high-latency," he said, "and you have to put glue logic around them." Further, he said, the manner in which the communications processors now handle packetization is "archaic."
In current systems, he explained, "the processor has to poll the DSP to ask if it has a packet, and if it does, then the processor has to DMA the packet into its memory, encumbered by a slow host interface." As far as processor and system bus utilization is concerned, that means "many long-latency reads," and the processor gets turned in to "a glorified DMA engine."
The PowerQuicc is "a highly tuned athlete," O'Connor said, "but it's not being used anywhere near its potential."
The new chip removes the bottlenecks by turning the system into "a write optimized environment," O'Connor explained, in which polling, packet transfers, DSP and host buffer management are all offloaded from the processor. It has four DSP ports, with each port switchable to handle up to eight DSPs. And since the C54x has four internal DSP cores, the Tsi920 provides individual buffers and channels for each to achieve optimal performance, O'Connor said.
The Tsi920 will be available at the end of this year in a 378-pin ball-grid array measuring 23 x 23 mm and with a 1-mm ball pitch. In quantities of 100,000, it will be priced at $41 each.
The first version will be quickly followed by versions for the Motorola 56K and Starcore DSPs and then by a single-port version and a version with a processor-direct interface.
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EETInfo No. 628