Sun Working to Eliminate Circuit Boards

lokedhs writes "Sun Microsystems is coming out with new chips without connectors. According to the article, this will have a lot of advantages: 'Performance, for instance, could greatly escalate because the speed of transferring data among chips and the number of channels for the transfers would increase. Energy consumption could also decline. Just as important, overall costs could fall, because defective chips could be removed like Scrabble tiles.' This technology will also lead to new CPU's without cache: 'The technique could also allow designers to remove the cache--the large pool of memory currently found on the processor--and put it on a separate chip. Caches were integrated onto processors to amplify bandwidth. Adding cache, however, bumps up manufacturing costs, as it greatly increases the number of transistors. With the bandwidth constraint gone, caches could once again be made independent without it having an impact on performance.'"

Comments

Re:Without connectors?

[hparker]

Think of it as lots of itty bitty low power radio transmitters and receivers.

Sounds clever to me. Electrical engineers have been constantly fighting unwanted interference in their circuits. Now they will be listening for it.

Dupe

[jdb2]

This was posted back in September of last year :

http://slashdot.org/articles/03/09/22/1055244.shtm l?tid=102&tid=137&tid=187

jdb2

Important info

[hcetSJ]

This makes the post make a little more sense, in my opinion (from the article):

By contrast, proximity communication relies on capacitive coupling--the ability of two electrically charged devices close to each other to interact. Transmitters on one chip can send signals to another. These signals are then amplified. A much higher number of transmitter/receiver pairs than pins can be inserted in a specific area, which allows for more simultaneous connections.

Can't get rid of the pins without replacing them with something else.

You need cooling and shielding

[Engineer-Poet]

(I searched all the comments for "crosstalk" and "RFI" and didn't come up with any hits... hope I'm not redundant before this is posted.)

The problem with capacitive connections is that you are, for all intents and purposes, using small radio links. This causes several issues to come to the fore:

• Your immunity to cross-talk goes down. Misalignment will exacerbate these problems.
• Capacitive receivers will also be able to pick up local RF fields. The computer will be much more vulnerable to external interference than it was before.
• The computer will also radiate much more than it did before, creating more RFI and leaking information that might be crucial (like crypto keys).

Making the chips the meat in a sandwich with metal sheets for the bread would help this a lot, because tightly coupled ground planes attenuate both radiation and reception. As long as you're putting a ground plane on top of the assembly it might as well do double duty as a cooling device, though I wonder what effect the heat-transfer compounds would have on transmission and crosstalk.