brejc8's Journal: Sun reveals UltraSparc road-map till 2005

Two (interestingly similar) articles from zdnet and businessweek report on Sun's revelations of future processors during an analyst conference in San Francisco. The UltraSparc IV will have two UltraSparc III cores on chip and will ship in 2004 on a 130nm process. UltraSparc V will arrive in 2005 and promises 5x more throughput than current processors. But the most exciting processor seems to be the Niagara server on chip. It uses several simpler cores on chip to allow fast execution of multi-threaded processes. The Niagara will also "extensively utilize asynchronous circuitry" as will UltraSparc VI and VII according to the register

Asynchronous circuitry

[Tet]

The Niagara will also "extensively utilize asynchronous circuitry" as will UltraSparc VI and VII

OK, but what does that actually give you in terms of concrete real world benefits? I know you've been messing around with asynchronous MIPS chips, so you ought to know about these things (and I freely admit, I don't). The concept of a clockless chip is a bit hard for me to get my head around, I have to confess. But presumably there are reasons for SPARC doing this. So what are they?

Re:Asynchronous circuitry

[brejc8]

Sun so far gave been using async to connect different frequency regions to eachother using elastic channels. This basicly means that parts with different clocks can talk to eachother without forcing one clock to be a division of another. I think they are probably letting the different cpus to stretch clock cycles and other neat tricks in order to squease the timing but still be able to communicate between units which have somewhat randon clock periods. Other papers I have seen from sun talk about generating clocks using a unit spread around the cell it drives. This makes the clock slow down or speed up depending on the tempriture or power supply to ensure correct operation and removes a lot of the wobble.

The other advantages are low power as when the cpu isnt doing anything then nothing switches. and speed as there is no clock wobble to desturb you so you can go much closer to the line.