Clockless ARM
Дискуссия на слешдоте.
Интересные цитаты:
...To overclock a self-timed design, you simply increase the voltage. No need to screw around with clock multipliers; as long as your oxide holds up, your traces don't migrate, and the chip doesn't melt...
...One of the neatest things about asynch processors is their ability to run in a large range of voltages. You don't have to worry that lowering the voltage will make you miss gate setup timing since the thing just slows down. Increasing voltage increases rise time/propegation and speeds the thing up. The grad students had a great demo where they powered one of their CPUs using a potato with some nails in it (like from elementary school science class.) They called it the 'potato chip'.
...But your assertion about critical path is slightly off. Asynch processors still have a critical path. If you immagine the components as a bucket-bregade and the data the buckets, then they may not all be heaving the buckets at exactly the same time anymore, but they will still be slowed down by the slowest man in the line. The difference is that critical path is now dynamic. You don't have to time everything to the static, worst-case component on your chip. If you consistenly don't use the slowest components (say, the multiply unit), then you will get a faster IPT (instruction per time) on average.
В глубине закопалось вот это:
http://hardware.slashdot.org/comments.pl?sid=182593&cid=15094648
Take look at this.
1997 - Intel develops an asynchronous, Pentium-compatible test chip that runs three times as fast, on the half the power, as it synchronous equivalent. The device never makes it out of the lab."
So why didn't Intel's chip make it out of the lab? "It didn't provide enough of an improvement to justify a shift to a radical technology," Tristram says. "An asynchronous chip in the lab might be years ahead of any synchronous design, but the design, testing and manufacturing systems that support conventional microprocessor production still have about a 20-year head start."
Вот те раз!
Интересные цитаты:
...To overclock a self-timed design, you simply increase the voltage. No need to screw around with clock multipliers; as long as your oxide holds up, your traces don't migrate, and the chip doesn't melt...
...One of the neatest things about asynch processors is their ability to run in a large range of voltages. You don't have to worry that lowering the voltage will make you miss gate setup timing since the thing just slows down. Increasing voltage increases rise time/propegation and speeds the thing up. The grad students had a great demo where they powered one of their CPUs using a potato with some nails in it (like from elementary school science class.) They called it the 'potato chip'.
...But your assertion about critical path is slightly off. Asynch processors still have a critical path. If you immagine the components as a bucket-bregade and the data the buckets, then they may not all be heaving the buckets at exactly the same time anymore, but they will still be slowed down by the slowest man in the line. The difference is that critical path is now dynamic. You don't have to time everything to the static, worst-case component on your chip. If you consistenly don't use the slowest components (say, the multiply unit), then you will get a faster IPT (instruction per time) on average.
В глубине закопалось вот это:
http://hardware.slashdot.org/comments.pl?sid=182593&cid=15094648
Take look at this.
1997 - Intel develops an asynchronous, Pentium-compatible test chip that runs three times as fast, on the half the power, as it synchronous equivalent. The device never makes it out of the lab."
So why didn't Intel's chip make it out of the lab? "It didn't provide enough of an improvement to justify a shift to a radical technology," Tristram says. "An asynchronous chip in the lab might be years ahead of any synchronous design, but the design, testing and manufacturing systems that support conventional microprocessor production still have about a 20-year head start."
Вот те раз!