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Terascale Computer Chip
February 10, 2007
Intel CTO discusses the company's development of terascale research chips at the last IDF
Intel Developer Forum is largely about firsts. One big first in 2006 was the terascale computer chip.
Don't get too excited. It's only a prototype.
In order to achieve memory bandwidth of terabytes per second (TBPS), Intel had to stack the memory chip underneath the processor chip.
That left engineers with the problem of getting data into and out of the pair of memory chip and processor chip at sufficiently high speeds.
There's memory bandwidth, and there's input / output (I/O) bandwidth.
The transfer of data between the memory chip and the processor chip requires memory bandwidth.
However, feeding data to the stacked memory and processor chips, and extracting data from the two chips, involves I/O bandwidth.
There's electrical signaling, and there's optical signaling.
Optical signaling involves lasers.
To move data at sufficiently high speeds to and from the memory and processor chip pair, engineers had to turn to optical signaling.
Electrical signaling was way too slow.
Not just any laser would do either. Engineers determined to build a laser out of silicon.
The point in building lasers out of silicon is to bring down costs.
Optical signaling has always had great I/O potential. The "problem is that the expense has always been extremely high" (p. 17).
However, if one could build a laser out of silicon and control it by a CMOS (complementary metal-oxide-semiconductor) process, chipmakers could then more affordably mass produce lasers via "standard manufacturing technology" (p. 16).
A laser was first built out of silicon in 2005. "It was the first time people made a laser in silicon" (p. 15).
What was needed next was a laser that was electrically pumped, rather than optically pumped. The laser that was built in 2005 was optically pumped.
Engineers have now at last succeeded in developing a laser out of silicon that is also electrically pumped.
That is the significance of this, "the first electrically pumped, hybrid silicon laser" (p. 14).