[Arm-netbook] How much to design A20 board?

[Luke Kenneth Casson Leighton]

On Wed, Sep 30, 2015 at 9:12 AM, joem <joem at martindale-electric.co.uk> wrote:

>>  no i get it - i added up once how many CPU Cards you could get into a
>> single rack-mount space, it was absolutely mad.
>
> Its how to wire all that that is difficult.
>
> I'm building a hypercube (with emphasis on hype :) ) with extravagantly
> lit LED conduits for the wiring to be passed through to reach all
> computing elements in a 3D mesh. The idea being if all is well, the
> conduits are a pleasant colour while if there are problem, the conduits
> light the way to the problem areas.

 niiice.

 btw do consider this as well, it expands up to infinite size:
 https://en.wikipedia.org/wiki/Nonblocking_minimal_spanning_switch

 assuming a 2-bar crossbar as the "base unit", basically to create the
next power of 2 up, you:

 * duplicate the entire network of switches made so far
 * put them side-by-side
 * put in another "layer"
 * connect every ODD numbered output from the last of the old layers
"straight through"
 * connect every EVEN numbered output to a port CROSS-WISE by adding
N/2 to its port number

(N is obviously the current total number of inputs and outputs)

if you have a 4-port router then obviously you would quadruplicate the
entire network so far, then connect the first one straight, the second
one increase the port number by (N/4), the third by (N/4)*2, the
fourth by (N/4)*3

 if you have a 32-port hub as the base unit you could go straight to
32x32 nodes (1024) with only 2 layers.

 i pretty much guarantee though that regardless of what you do, you'll
end up with more wires and more network switches than anything else :)

l.