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Unread 22-11-2013, 16:30
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Re: Driver station power

Quote:
Originally Posted by yash101 View Post
That makes sense because the hub is the bottleneck! The hub isn't too fast and is serving so many cogs that there are very few times where the hub will be able to be used well! That's like my computer, where the hard drive (SSD) gets a seven, but the processor gets a three, causing my computer to be veerry slow!
Correct. If you then extend that to using external resources that's an even deeper bottleneck for the Propeller.

However the problem is not horrible. The nature of the Propeller Hub mechanism is such that every Cog gets a fair chance at access to the Hub. Even if a Cog might wait 8 clock cycles to get that chance. For an environment where code might not be stable that unalterable Hub behavior is a great way to stop a hung Cog from stopping other Cogs.

So the nice part is that unlike a single processor or SMP computer you can create a single tight process in the Cogs and not have to worry about random interrupts and task scheduling. You can do task scheduling if you want but it's entirely optional. As a result one can create some impressive artificial peripherals inside the Propeller. Hooking up a monitor to a microcontroller without a real interface even with limited colors is a pretty neat trick and the timing to make it work would be difficult to work out if not for the design of the Propeller itself. The Propeller can not just do that but the left over Cogs can be sent off on other tasks. It's really quite possible to divide up the Cogs and the Hub shared memory between different people's work even within a single Propeller let alone many.

It's very much like how mainframes work and large enterprise networks of computers.

Last edited by techhelpbb : 22-11-2013 at 16:35.