Until we got up to about a 33MHz processor clock, there was no question that the bus would be clocked as fast or faster than the processor, but we have now reached the situtation where processors are routinely internally clocked as much as five or eight times their input-output circuitry, which means that a 250MHz processor is fine if you’re doing the kind of work where the processor holds lots in its head much of the time, but not much use if you’re doing heavy database work with copious disk accesses – in that case, a processor any faster than the bus buys you virtually nothing. Now Siemens AG, speaking on behalf of its pals IBM Corp and Toshiba Corp as well as itself, is claiming to be first with a part that should greatly ease the bottleneck and enable buses to run at between 400MHz and 800MHz. The part is a variant on the humble dynamic RAM, a Synchronous Link dynamic or SLDRAM, but the first SLDRAM is not scheduled for completion until early 1998. The parts are aimed at high- end personal computers, servers, workstations and consumer electronics products, and can transfer data at rates up to 3.2Gb per second, depending on the memory configuration. The parts will be made in 0.25 micron CMOS, and Mosaid Technologies Inc, the Ottawa-based company where lots of clever chip-related advances have come over the years, is to design the SLDRAM using the 0.25 micron process. In the coming weeks, a design team at Mosaid will be joined by engineers from Siemens and other team members.
