ASIC DIY hardware developing

Hi Folks
Im new to this list. Im a very experienced hardware developer, and VERY interested in DIY ASIC miner development. Keen to hook up with some firmware types and get something going *fast*.

Does anyone have the pinouts/spec for the Avalon chips yet?
From what I have been seeing, there are 8 data/clock lines everything else is power. Running a bunch of these on a board would be better done on 4 layer, both for power supply considerations (less glitches/crashes) and also for heatsinking (the power/ground planes will conduct out a lot of the heat, making less demands on the active heatsinking)
My rough calculations :
the chips are claimed as 282MH/s per unit. This means in a 60GH unit there are ~ 210 chips. 600W for the chips (20W of power supply loss) ->
The chips will dissipate ~2.8W each. This is capable of being dissipated passively, althuogh massively arraying the chips in a small space will make this not so thermally favorable.
The chips, mounted in a 4 layer PCB with a passive heatsink (doesnt have attached fan) will be OK, although a fan to drive air over the PCB would be better.
Im thinking at first a small demo unit, maybe 1-5GH range would be essentially a 'pocket' unit. One interesting approach would be a truly pocket size unit, capable of being powered completely by a USB socket. This is not much power, but it could be a residual device. You could take it wherever you go, plug it into your laptop, spare USB port on your computer at work etc. every time you have a computer near you, there is a bit of boosted hashing power. Its also a cheap interesting intro to someone who doesnt want to outlay a huge amount of money first up. This size of unit, heatsunk to a metal case, could be totally passive cooled, no need for a fan
The 256MHz clock. Would have to get a clock multiplier and run from a lower xtl. This is a not a difficult exercise hardware wise, but it does need careful layout - again, 4 layer boards are a BIG advantage at this speed, and through hole stuff is just a no go.
Another thing would be the expandable version. In the interests of cheapness, and parts commonality, this would be an interesting approach -> Start with a board of a given size - the full USB interface and power converters etc are all on here, + some number of Avalon chips. There is a set of expander bus plugs.
The expander board is the *same PCB*, minus the USB port. Basically, you just dont install some of the parts, and plug it to the expander ports. The main unregulated power bus goes to each board, the regs for the board are on each one. That way the power supply expands linearly with the processing power.
The advantage of this way of going is that there is only ever 1 PCB to fab. This reduces build costs as well as design time considerably.
BTW, 4 layer can be PCBs fabbed pretty cheaply, especially if there is a good deal of group interest. It isnt that expensive even in small numbers
DIYing this sort of thing... It is seriously *advanced* for DIY for most people. There are ways of dealing with an exp pad QFN with hand soldering (!!), although reflow methods are much better unless you are only wanting to do a couple of chips, as it is a bit finicky. On the other hand, a cheap reflow rig can be had for under $300. If you are serious about doing this, that is probably an acceptible cost for the setups. The chips are looking like being $10 each, and 5 chips to a 1GH, so 50GH worth of chips is 2500. About what a 50GH miner costs, going by ebay costs. But the thing is that this could pay for the expansion with lower initial outlay. Say build a 5GH unit, and the proceeds fund add on 5GH cards, build from there. just a thought.
Anyway, just putting some ideas out there, keen to hear from other developers who would want to work on something like this. Ive seen a few comments on the list about other people doing some hardware work, but not seen anyone got designs out yet?
Get in touch..
Cheers
Dan