Well, I think that the reason the async chips are not being used is quite simple - a clocked system is much easier to design and verify. You know how long before and after a clock edge your signal needs to be there to be recognised. You know that if these constraints match across your system, it will work. Yes, this makes the system as fast as its slowest link - some circuits operate near their limits, some are actually wasting the time. But it works. An asynchronous design would be a pure hell to debug - that's probably why the industry doesn't (yet) mess with it.
Not so. In fact, one of the greatest problems with clocked boolean design is the interference caused by all the clocks on the chip. Fabrication will routinely result in broken chips, forcing multiple redesigns and long development cycles.
Tremendous resources are dedicated to getting around this problem. Also, you can't really just change the design 'a little bit', as doing so results in more interference issues. Want to add a new unit to a clocked boolean logic chip (a new cache, 3d unit, new pipline, etc)? Sure you can do it, but it will require fundamental redesign as adding those clocks associated with the new unit will interfere with other clocks on the chip, and other clocks will interfere with your new unit. The fact that they all have to fire off simultaneously, generating electromagnetic interference, is a real needle in the eye for chip designers.
With well thought out async, all you have to do (more or less) is add the unit to the design. The 1st fab should work, no redesign cycle required. You can add cache memory or whatever and as long as the design is logically valid you will have a functioning chip in a few days time (as long as it takes to fab the chip). Try that with syncronous logic.
This 'randomness' exists both in syncronous and async logic. Clocked boolean logic will not handle the same operations exactly the same way twice with respect to timing at the gate level, but the clock hides that (that's why it's there). With clockless logic, other mechanisms hide that.
In the case of Null Convention Logic, it's the extra signal saying 'wait until I'm done!' to the next logic unit. This results in relative dataflow being more random-like. However, both approaches use design to insure the end result is properly achieved.
With Null Convention Logic, this 'relative randomness' means the chip is producing more 'white noise' since multiple clocks are not joining together to produce a steady electromagnetic frequency. This should make design easier as you don't have to fight your own chip design to keep it from interfearing with itself. This is a HUGE problem with current clocked designs. I believe it results in many forced re-designs to get it right, and the problem only gets worse with higher clock rates and bigger chips.
I have heard the argument that Senator McCain is very anti 1st amendment, but every time I've heard that argument without exception, it has gone something like this:
Senator McCain is trying to force campaign finance reform down the throats of Freedom Loving Americans(tm). It is a 1st amendment right for corporations and wealthy Americans to influence politics through big money contributions, which is a 1st amendment issue. Therefore, Senator McCain is very anti 1st amendment. If you support the 1st amendment, then you MUST support unregulated big money influence in politics (like the big money influence that buys the DMCA and now SSSCA on behalf of the tiniest minority of the public).
Personally, I don't see purchasing legislation as a 1st amendment issue, as it means 99% of all americans have no "1st amendment rights" which can counter those of big money influence. To say the size of your bank account should give you more 1st amendment power is corrupt to the core at best.
Now that said, Senator McCain may still be an enemy of the 1st amendment - I would like to see the argument as to why though - an argument that doesn't equate wealth with 1st amendment 'rights', as 'rights' like those given by the 1st amendment necessarly require those rights for most individuals to be roughly equal.
Suggesting even in quotes that the US is in recession sure sounds like repackaged mass media hype to me. In fact, a recession requires 2 seperate quarters of negative growth. The US economy grew about 1% in the 1st quarter of 2001 - which means even if we are heading for a recession (which the media jackles want more than anything else to pump up headlines) we won't officialy be there until the last quarter of this year!
While the economy looks bleak compared to last year, remember last year was a fluke, and the markets were WAY overinflated! Lets try on the 'Recession' word when we are closer to that time.
PS - slashdot IS in fact a great break from the "Infotainment" which our media has degraded into - I don't mean so much to flame slashdot as to remind everyone that "Recession" should only be used for... Well, for a Recession.
Slashdot Mirror
Well, I think that the reason the async chips are not being used is quite simple - a clocked system is much easier to design and verify. You know how long before and after a clock edge your signal needs to be there to be recognised. You know that if these constraints match across your system, it will work. Yes, this makes the system as fast as its slowest link - some circuits operate near their limits, some are actually wasting the time. But it works. An asynchronous design would be a pure hell to debug - that's probably why the industry doesn't (yet) mess with it.
Not so. In fact, one of the greatest problems with clocked boolean design is the interference caused by all the clocks on the chip. Fabrication will routinely result in broken chips, forcing multiple redesigns and long development cycles.
Tremendous resources are dedicated to getting around this problem. Also, you can't really just change the design 'a little bit', as doing so results in more interference issues. Want to add a new unit to a clocked boolean logic chip (a new cache, 3d unit, new pipline, etc)? Sure you can do it, but it will require fundamental redesign as adding those clocks associated with the new unit will interfere with other clocks on the chip, and other clocks will interfere with your new unit. The fact that they all have to fire off simultaneously, generating electromagnetic interference, is a real needle in the eye for chip designers.
With well thought out async, all you have to do (more or less) is add the unit to the design. The 1st fab should work, no redesign cycle required. You can add cache memory or whatever and as long as the design is logically valid you will have a functioning chip in a few days time (as long as it takes to fab the chip). Try that with syncronous logic.
This 'randomness' exists both in syncronous and async logic. Clocked boolean logic will not handle the same operations exactly the same way twice with respect to timing at the gate level, but the clock hides that (that's why it's there). With clockless logic, other mechanisms hide that.
In the case of Null Convention Logic, it's the extra signal saying 'wait until I'm done!' to the next logic unit. This results in relative dataflow being more random-like. However, both approaches use design to insure the end result is properly achieved.
With Null Convention Logic, this 'relative randomness' means the chip is producing more 'white noise' since multiple clocks are not joining together to produce a steady electromagnetic frequency. This should make design easier as you don't have to fight your own chip design to keep it from interfearing with itself. This is a HUGE problem with current clocked designs. I believe it results in many forced re-designs to get it right, and the problem only gets worse with higher clock rates and bigger chips.
I have heard the argument that Senator McCain is very anti 1st amendment, but every time I've heard that argument without exception, it has gone something like this:
Senator McCain is trying to force campaign finance reform down the throats of Freedom Loving Americans(tm). It is a 1st amendment right for corporations and wealthy Americans to influence politics through big money contributions, which is a 1st amendment issue. Therefore, Senator McCain is very anti 1st amendment. If you support the 1st amendment, then you MUST support unregulated big money influence in politics (like the big money influence that buys the DMCA and now SSSCA on behalf of the tiniest minority of the public).
Personally, I don't see purchasing legislation as a 1st amendment issue, as it means 99% of all americans have no "1st amendment rights" which can counter those of big money influence. To say the size of your bank account should give you more 1st amendment power is corrupt to the core at best.
Now that said, Senator McCain may still be an enemy of the 1st amendment - I would like to see the argument as to why though - an argument that doesn't equate wealth with 1st amendment 'rights', as 'rights' like those given by the 1st amendment necessarly require those rights for most individuals to be roughly equal.
Suggesting even in quotes that the US is in recession sure sounds like repackaged mass media hype to me. In fact, a recession requires 2 seperate quarters of negative growth. The US economy grew about 1% in the 1st quarter of 2001 - which means even if we are heading for a recession (which the media jackles want more than anything else to pump up headlines) we won't officialy be there until the last quarter of this year! While the economy looks bleak compared to last year, remember last year was a fluke, and the markets were WAY overinflated! Lets try on the 'Recession' word when we are closer to that time. PS - slashdot IS in fact a great break from the "Infotainment" which our media has degraded into - I don't mean so much to flame slashdot as to remind everyone that "Recession" should only be used for... Well, for a Recession.