[Beowulf] modular motherboard prototype

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Fri Aug 21 12:04:09 PDT 2009

From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org] On Behalf Of Peter St. John
Sent: Friday, August 21, 2009 10:23 AM
To: Beowulf List
Subject: [Beowulf] modular motherboard prototype

Slashdot pointed out a prototype modular motherboard; a big mobo is made from snapping together a bunch of little ones: http://www.wired.com/gadgetlab/2009/08/modular-motherboard/

'David Ackley, associate professor of computer science at the University of New Mexico and one of the contributors to the project [says] "We have a CPU, RAM, data storage and serial ports for connectivity on every two square inches." '
Each X Machina module has a 72 MHz processor (currently an ARM chip), a solid state drive of 16KB and 128KB of storage in an EEPROM ... chip. There's also an LED for display output and a button for user interaction.'

The modules share power & data through a single connector, recognize the presence of neighbors and can load each others programs automatically.

If the connectors are the usual male/female (not certain from the picture) then snapping them together would be a bear, since the vertical pair of pins wouldn't be aligned when the horizontal pair hasn't been snapped in yet, and vice versa.



There are lots of hermaphroditic connectors around, or, for that matter, you arrange both male and female contacts in the connector. There is probably also a relative orientation requirement for these boards.. e.g. they are all in a plane, and they all have to have the same 2D rotational orientation (North up on all boards, or something similar), so then you could have gendered connectors, and still flexible interconnects.. The left side has female, the right male, for instance.

In the case of the Illuminato boards, it looks like they're simple female 0.1" spaced connectors, and you'd put a 7x1 pin header in between to connect them. (it might be a 2x7 array for 14 pins.. the picture isn't totally clear on the website.

These days, with high speed serial interconnects, especially with wireless (optical or RF), one should be able to build nodes that can be literally thrown together any old way, except for the power. And there are solutions for power distribution as well.

The folks doing swarms and emergent behavior are big into this kind of thing.

AS far as the architecture goes, I wonder if these guys ever looked at transputers and their related architectures.

And anyone on this list is well aware that the real challenge isn't the hardware, but the software, and making use of that amorphous blob of processing with random interconnects for anything other than "toy" applications.

As the Wired article says:
"..there are many details that need to be worked out..."
"..haven't benchmarked .. power consumption and speed.."

We can guess, though.. It's an ARM running at 72 MHz, for which they claim 64 Dhrystone MIPS. Some of those are going to be burned in interprocess communication. The LPC2368 (which is what they use) datasheet says it draws 125mA at 3.3V running at 72MHz. (I'm pretty sure that doesn't include power to drive I/O pins, which is separately supplied).  That's about half a watt.  So they're getting about 128 DMIPS/Watt.
Let's compare to, say, a Core2 Duo at 2.4GHz, with 7000 DMIPS, burning about 35W, or 200 DMIPS/Watt.  They're in the same ballpark, but I suspect that in a "real" system doing "real" work, the overhead moving data from one tiny processor to another will consume easily half of the overall resources.

SO right now, this is a cute toy. I wouldn't mind having a few dozen modules to fool with.  (they're about $60 each)
(compare also, what if you went out and got a box of Gumstix)


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