Go Down

Topic: Ponder This (Read 3922 times) previous topic - next topic

Jeremy1998

Why don't we use HDMI or something very similar in computers? I mean there are companies like Monster Cable (this is not spam, I promise) that have HDMI cables that claim to be capable of over 21GB/S! I know they're expensive, but they sell them on eBay for like $30.  

AWOL

#1
Dec 19, 2010, 09:32 pm Last Edit: Dec 19, 2010, 09:34 pm by AWOL Reason: 1
We do use stuff very similar.
They're called PCB tracks.

I know a guy who designs X-ray image processors.
His cards are all linked with professional, studio quality digital TV interconnects.

AlphaBeta

#2
Dec 19, 2010, 09:35 pm Last Edit: Dec 19, 2010, 09:41 pm by AlphaBeta Reason: 1
HDMI is actually 'just' 10.2 Gbit/s not 21 GByte/s (which is more than 16 times as fast).
The cable was rated for 21 Gbit/s :)

One can easily use HDMI with computers. My PC has a HDMI connector.

Jeremy1998

Right, but that's for video. It would be really good for connecting nodes to make a supercomputer...

AWOL

#4
Dec 19, 2010, 09:42 pm Last Edit: Dec 19, 2010, 09:43 pm by AWOL Reason: 1
Quote
Right, but that's for video

No, that's for digital data.
Quote
It would be really good for connecting nodes to make a supercomputer...
Depends on the architecture.
Good for short, point-to-point, lousy for bussed systems.

Jeremy1998

True.

I don't know... I just got an idea when I was looking at cables for my TV.

AWOL

#6
Dec 19, 2010, 10:01 pm Last Edit: Dec 19, 2010, 10:01 pm by AWOL Reason: 1
Besides, I think glass is still cheaper than copper.
And I'm not talking SPDIF.

jezuz

Plus wouldn't the bottlenecking be the hardware, not the interconnects?

cmiyc

There is nothing special about HDMI and its bandwidth.  The reason it has so much is because it is made up of multiple high speed serial lanes.  There are 3 lanes, each running 3.4Gb/s for a total of 10.2Gb/s.  

The underlying protocol is what makes it "HDMI" and is specifically targeted for audio/video.

If your interest really was, communication between computers then you'd want to look at Infiniband.  Generally it is used for intra-computer communication.  Up to 12 links can be combined giving a maximum throughput of 300Gb/s.  That is 12 Links each running about 25.7Gb/s.

Anyway, look at Infiniband.  Electrically very similar to HDMI but the protocol is design for interconnecting computers instead of TV.

http://en.wikipedia.org/wiki/InfiniBand
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

Divyanshu

Even though glass is cheaper than copper, it's very brittle and need the extra cladding on the cable.

cowjam

I thought the problem with supercomputers was clock speed rather than the bandwidth available defined by the physical property of whatever the buses are made of?

For every clock cycle of a 3Ghz processor light only travels 10cm. I'm under the impression this is why everything's multicore rather than just faster.

keeper63

Quote
Anyway, look at Infiniband.  Electrically very similar to HDMI but the protocol is design for interconnecting computers instead of TV.


...and that's about all any mere-mortal can do. While the cost of Infiniband (and similar interconnect technologies) have come down in price over the years, they are still waaaaaaaaaay out of the price-range of an individual.

;D
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

cmiyc

The cost of the interconnect isn't the prohibitive factor.  Any kind of hardware that can generate enough data to warrant a 4x 25Gb Link is going to be significantly more expensive than a couple of SERDES, Connectors, and Cables.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

Go Up