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Author Topic: So what is XMOS good for?  (Read 14207 times)

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Offline Piru

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Re: So what is XMOS good for?
« on: February 22, 2010, 03:59:14 PM »
Quote from: Vulture;544414
I, for one, would be happy if it could emulate classic miggy and keep this load (or a big part of it anyway) away from the CPU.

It can't.
 

Offline Piru

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Re: So what is XMOS good for?
« Reply #1 on: February 22, 2010, 04:48:52 PM »
Quote from: Tripitaka;544466
@ Piru

Please justify your comments. "No" is meaningless without an explanation.
Justify? You mean "elaborate" I guess.

Right here we go:

1. The device has 64Kb of RAM. That is way way too little for most tasks. Certainly too little for any kind of emulation.
2. The device has no direct access to system RAM (the access is really slow and software aided. The device doesn't cache such memory accesses). Emulation needs to have fast access to the state information.
3. Emulation in general isn't suitable for threading. That's why we don't (and won't) have any dual core support in WinUAE, for instance. Thus, having 8 or more cores doesn't make any difference.
4. Trying to use XCore for some parts of the emulation would probably only end up slowing the whole down. It'd be much faster to do the whole thing with the main CPU (which has direct fast access to system memory, with L1 and L2 caches).

These are the obvious reasons why XMOS sucks at emulation. Same reasons make many other things unsuitable, aswell. For example using the device for some kind of graphics or audio acceleration.

I haven't even looked into instruction set and such issues, yet. What is clear however that there is no FPU, which means any floating point math would need to be done with integers (possible but very slow).
« Last Edit: February 22, 2010, 04:56:09 PM by Piru »
 

Offline Piru

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Re: So what is XMOS good for?
« Reply #2 on: February 22, 2010, 08:19:47 PM »
Quote from: hektic;544505
Any ideas on what the XMOS "could" be used for?

Other than use it as a marketing gimmick, no.
 

Offline Piru

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Re: So what is XMOS good for?
« Reply #3 on: February 22, 2010, 10:37:31 PM »
Quote from: Hans_;544539

We're not going to know what can be done with it until the machine is available

We know what can't be done with it, however.

Quote
If you don't see the point in the XCore chip, then maybe you should focus on the rest of the machine; multi-core >1.6 GHz, PCI-Express, etc.

Somehow the whole marketing drive of this "X1000" seems to be built around this chip. If it's not so important, then why make such a big deal about it? I find this odd.