It was explained in the "Open questions..." thread that Dwolla withdrawals are also risky:

http://forum.bitcoin.org/index.php?topic=33086.msg413909#msg413909

It sounds to me like Tradehill did what they had to do to protect both themselves and their customers.

Good point. So, I'll revise my question: How is "I'll hold your wallet.dat for security, and I promise not to spend your money" any more obviously a scam than "I'll give you a new wallet.dat for security, and I promise not to keep a copy"?

P.S.: Speaking of moderation, shouldn't this thread be in Meta? 

What is the difference between:

• A service provided by a stranger on the Internet which holds on to my wallet.dat and promises not to do anything naughty with it.
• A service provided by a stranger on the Internet which sends me a new printed wallet.dat and promises to delete any temporary copies they might have of it.
• My bank, which asks me to hand them all my money and assures me that it'll always be there when I want it back.

Ok, my bank at least has a local brick and mortar branch for me to burn down if they steal my money, but otherwise I don't see how any one of those items screams "SCAM!" any more than the others. They all rely on trusting strangers with my money.

Personally, I do not presently have any reason to want to hand somebody else my wallet.dat for safekeeping, because I think I can can protect it well enough myself. Still, it seems interesting to me to see a claim that a hold-on-to-your-wallet service must be a scam, coming from somebody who asks me to give them money in order to obtain a wallet.dat that they had access to. I think I'll pass on both services.

I would also like an ignore user option. I would use it sparingly, but it would make my time here more enjoyable.

If we promote it as "auditing" instead of "mining", that should drive the difficulty down by making it sound boring! But on the negative side, it may attract Scientologists. 

Oh, I thought you had a 6990 based on your shirt. I guess you were just teasing us. 

I'm jealous! I just have a pair of 6970s. 

It's secede, not succeed. And regarding the idea of pressing some helpful rape gangs into service to seize a rural area, the US has historically been quite uncooperative about attempts to secede from the union.

Just as Bitcoin is distributed and enables the creation of a shadow economy that can quietly coexist alongside the various "legitimate" currencies of the world, shouldn't the proposed Bitcoin nation be distributed and exist as a shadow nation quietly occupying the same space as all of the "legitimate" nations in which Bitcoin participants live? If a person wishes to opt out of the traditional nations and their economies, why should they need to go somewhere else to do that as long as they can remain unobtrusive enough to avoid detrimental attention from the traditional government(s) that are in control in their local area?

I suggest that the nation of Bitlandia (or whatever it might be called) exists anywhere and everywhere that its citizens choose to live and travel.

After a lot of flailing around and hair pulling, I managed to get my dual card, dual monitor setup working. I also found out how to crank up my GPU fan speed, and my rig is now mining along at about 540 MH/s with GPU temps of 72 and 65.

I'm new here, and I hope this isn't a dumb FAQ. I've successfully mined a bit with phoenix on an XFX 6790 under Debian Squeeze with SDK 2.4. Today I added a Diamond 6970, and it seems that I don't know how to mine on dual cards yet. I have one monitor plugged into each card, running with XINERAMA=on, if that matters. When I run phoenix, it's only mining on the first GPU (which happens to be the 6970). If I try DEVICE=1, then it runs on the built-in GPU in my CPU. Any hints for a clueless noob?

While I'm here, I notice that the 6970 runs a lot hotter than the 6790. With little or no overclocking, the 6970 is running at 90 deg. C while the 6790 runs at around 68 deg. C.

I'm probably in about the same boat as JoelKatz. I would not call myself an ASIC expert, but I've been involved in ASIC design projects for nearly 20 years, so I have a reasonable feel for the time and money it would take to get the job done in the context of a small engineering startup. I agree that it's about a $2 million, 1-year job to get one to production, using the open source FPGA miner as a starting point.

So, here's the thing. I have the technical expertise to participate in such a project, and I'd even enjoy it. However, I presently have a good job at a huge semiconductor company, with good compensation and a good expectation of stability over the next few years. If I were to pursue a Bitcoin mining ASIC project, then life might be good for up to a year, and then I'd find myself out of work. I have a mortgage to pay, and my bank doesn't take Bitcoins yet. And I don't have a nest egg stashed away that would let me do a one-time job like this and then be out of work for a while as I look for the next job. I'm interested in Bitcoin and would like to see it succeed, but I don't think it's in a state yet where I'd bank my career on it.

There may be good ASIC engineers out there who are in a much better financial/career position than me to take on this sort of project. If there's also somebody with a couple million bucks they'd like to front on this, then GPUs might go the way of the CPU for Bitcoin mining by this time next year!

Regarding USB vs. Ethernet as the interface for these proposed ASICs, there are lots of options for embedded microcontrollers that would be suitable for managing a herd of ASIC miners. A little ARM processor, running Linux, with an Ethernet interface would be quite do-able. The end product could be a standalone appliance that just needs to be plugged into power and an Ethernet jack, configured to log in to your favorite pool, and then left alone. There are even all sorts of off the shelf embedded microcontroller boards that could be used for prototyping.

Maybe yes, maybe not so yes! The numbers I threw out are based on making the ASIC in the context of a start-up tiger team in Southern CA, with engineering costs and wages typical for the area. Doing it in China changes the salary numbers. If it's done by a company that already has access to the ASIC tools, that helps, too (i.e., I have access to all of the software needed to do ASIC design at work, but I'm just not in a position to use company resources on this kind of thing without getting fired). Maybe these folks are in a position to get better pricing on the first silicon (like, maybe a cousin in just the right position at a semiconductor foundry can slip the job into a shuttle run?). Maybe some guy who owns an ASIC design house in China happens to be a Bitcoin enthusiast, and decided to pursue the ASIC design with resources he already had? Maybe some mid level manager decided to put his team on the job without getting approval from higher up? Maybe it's all just a scam?

In any case, thanks for finding that! I think it's worth watching to see if it's real.

Thank you, and I'm glad that I could contribute something to the thread!

Now, please don't take my negativism about making an ASIC miner the wrong way. If Bitcoin does succeed in becoming a viable world currency as we hope that it will, then I think that a time will come when it will make sense to make mining ASICs. I don't think that time is quite yet, and I just wanted to help folks understand what "make an ASIC" really means. I think it would be a fun project to work on, but I don't have a couple million bucks to spend on it just now.

One thing that would help reduce risk in the eyes of any potential ASIC development investor would be if the same hardware could also perform other useful functions with an exploitable market, such as cracking passwords or generating pseudorandom porn. This may not be the right thread to brainstorm in this topic, but I am curious about what other useful tasks could be performed by hardware that is designed to mine efficiently, whether it's hard coded into an ASIC with just the right kind of configurability, or programmed into an FPGA.

My mind is a warehouse of useless trivia.

The time it takes to create a production-ready ASIC is not constrained by processing power; it's not something that you can speed up by throwing more computers at it.

The one year benchmark is a rough estimate of the total time needed for an ASIC of low to moderate complexity, designed by a small team of experienced engineers (say, around five of them, with various different specializations), based on my experience in the industry, both directly working on ASIC designs and in other roles related to development, test, support, etc. It's hard to explain where all of that time and money goes to somebody without direct experience in the field, but I'll try to throw out examples of some of the major costs and time-drains. This list is nowhere near exhaustive... bringing an ASIC design from concept through production readiness is a terribly complex task which involves direct action by many dozens of people over a long period of time.

First, the engineers. Experienced ASIC engineers don't come cheap. They'll expect six-figure salaries, and if you don't want to give them that, then they'll go work for somebody else. They also won't just go work on a one-off project like this without some strong incentive, if it means leaving a large, profitable company with good compensation, benefits and stability. For an ASIC comparable to a scaled-up version of the FPGA designs discussed in this thread, I'd estimate that 4-6 engineers would work on it directly. One would be dedicated to physical design (place and route, managing the foundry libraries for the other engineers, etc.). One would be dedicated to production and testing. Then one to three would work on the design itself. So, there are 3-5 expensive, skilled, experienced people who each expect to make north of a hundred grand a year plus benefits (and they will earn that pay with long hours and a lot of difficult work). If you want them to work as contractors and then go away, rather than staying at your company for several years, then double their pay.

Then, there's a mask set for each release to the chip foundry. If your team is very skilled, very careful, and very lucky, they might come up with a production ready part on the first try, but it's safer to assume at least two mask sets. Guess what: a full mask set for a fairly recent process will cost around a quarter million dollars. Prices can be lower, particularly if you share the wafer with other jobs (usually called a "shuttle run" in the industry), but it's still Real Money.

Ok, those engineers are expensive already, but they can't do anything without tools. If you haven't been exposed to the semiconductor industry before, you might be utterly stunned by the cost of ASIC design software. That team of 3-5 engineers will probably need over $50k per year for their software licenses. They'll also need computers to run that software on. And somewhere to work. Heating and air conditioning are nice, but it's amazing what horrible conditions people will put up with if there is enough money in it. Don't skimp on coffee, soft drinks and snacks, though because that investment really pays off in increased productivity.

The team will probably spend three or four months on the design of a chip that's basically a scaled up version of the FPGA designs discussed in this thread, including design, simulation, place and route, timing closure, packaging, bond-out, and all of the other stuff needed. Once they release the design to the chip foundry (called "taping out"), it'll take a couple of months before the first silicon arrives. Of course, you need to keep paying the engineers while you're waiting if you want them to be around to debug the chip when it arrives. Of course, folks aren't just sitting on their hands doing nothing while the chips are being made; there's also the production test program that needs to be developed.

Once the first silicon arrives, you'll be spending some quality time in the lab debugging the chip, and hopefully finding work arounds for any bugs that let you avoid an expensive and time consuming design spin. Remember, the ASIC equivalent of typing "make" costs a quarter million bucks and takes a couple of months. Presumably, you had the foresight to design any needed PCBs for the chip bring-up effort in the lab. You'll probably be amazed by the cost of the production test board and its socket.

Oh, yeah, you'll also need some expensive test equipment for the lab work. We're talking about a GHz chip here, so a $100 logic analyzer from SparkFun won't cut it. Luckily, the test equipment can be rented instead of bought, saving you tens of thousands of dollars (but still costing you thousands of dollars).

After you spend all of this time, if you have done everything right, you now have a working chip design. Now you get to start manufacturing the chips and trying to sell them. And dealing with customer support. And production issues. And testing. And returns. By the time all is said and done, it's not worth starting the job unless you expect to sell several millions of dollars worth of chips to the manufacturers who make products that use them.

I'm sure I've missed a lot of details, but I hope that this has helped explain a little bit of what's involved in making an ASIC.

Regarding ideas about an ASIC miner, I believe that it would be very feasible on a purely technical basis. The only snag is that it would take on the order of a million dollars and a year of work up front to assemble a small ASIC team, design the chip, fabricate the first silicon in a fairly recent process, debug it, spin it once if necessary, develop production test, and get that first prototype ASIC-based mining platform out to the market in sample quantities.

My whole career has been in the semiconductor industry so far. I could certainly assemble a design team to do this. All I would need is a million or two dollars and some expectation of an ROI greater than I'd get by simply putting the money in a savings account. Anybody want to fund a small start-up in southern California to make mining hardware? :/

A well-designed ASIC should be able to achieve much higher hash rates than any FPGA implementation in a given amount of die area. A custom-packaged FPGA would just change the packaging cost with no performance benefit, and the package cost is a smallish portion of the entire chip cost. It wouldn't even affect the PCB cost significantly, since we have the option of simply leaving a lot of the IO pins unconnected. The Spartan 6 FPGAs have a lot of pins, but they're not on a terribly fine pitch so it doesn't take advanced PCB design rules to route the outer few rows of pins and leave the inner rows of IO pins unconnected.

If you're willing to spend ASIC money, you want to end up with an ASIC when you're done.

Thanks for the data point!


Back when we were a start-up, I would have done it without asking. Now that we've been bought by a much larger company, and then bought again by a huge company, it wouldn't fly. They made a point of bussing us all a hundred miles to the headquarters and showing us how closely they watch everything in their NOC... I might be able to sneak some trial synthesis runs into the queues, though.

Regarding the comments about the relative utility of FPGAs vs. GPUs, I'll say that if FPGAs had no utility beyond Bitcoin mining, they wouldn't be sold in the first place. With a little thought about the feature set required by other users, FPGA mining-optimized platforms can be made to serve a larger market than just Bitcoin miners. Also, with an XC6LX150 costing around $160 in single quantity, I think they'd easily resell for half of that to somebody who would desolder and reball them. FPGAs are quite useful; they just have utility to a different market than GPUs.

The price of the FPGA itself is only part of the reason for the relatively high cost of generic FPGA evaluation boards that are suitable for mining experiments. The FPGAs which have enough gates for an unrolled mining engine also have a large number of IOs, and are generally in big BGA packages. The eval boards bring all of that IO out, and it takes a lot of layers to escape so many nets from the chip. An LX150 requires about 16 layers for full die escape in a mainstream PCB process. The Virtex 5 board on my desk has 20 layers. We have big emulation machines at work with over 50 Virtex 6 parts mounted on 38 (!) layer boards (before you ask, no, I don't have access to those for mining experiments!). Off the shelf FPGA boards don't look price-competitive with GPUs, but the gap should be much smaller on low-layer-count boards optimized for high gate count, low IO applications. Things start to look even more interesting in hypothetical larger arrays, when you factor in the costs of computers, power supplies and cooling to host bunches of GPUs vs. the lower power and cooling requirements of FPGAs.

Please forgive me if this has already been mentioned. I'm curious about how the Spartan 6 FPGAs (particularly the XC6LX150) are performing vs. the Cyclone parts. I gather that it's harder to route the unrolled miner design in the Xilinx parts than in the Alteras, but what sort of final clock rates are achievable in the Spartans with adequate cooling?

The Spartan 6 FPGAs look compelling to me because of their relatively low cost, but it's not clear to me whether they compete against the Altera parts in terms of $/Mhash. If they are cost-competitive and achieve similar hash rates, then I'm tempted to try making low-cost boards optimized for low I/O pin count applications like this. I can envision a single-FPGA board with a USB-interfaced microcontroller to babysit it, as well as a larger form factor with an array of LX150 FPGAs (say, 16 of them) under the control of a supervisor (possibly an LX45T with an ethernet interface, running Linux on a Microblaze core, for a fully stand-alone mining appliance). I'd try to bring out as much of the I/O as I could get away with on a 4-6 layer board to make them more generically useful.

We use a lot of FPGA platforms at work for hardware emulation (mostly Virtex-5 XC5VLX320 parts). I have one sitting on my desk that's not doing anything while I'm not at work, but I don't think it'd be wise for me to run miners at work over the closely-watched corporate network. Based on the FPGA mining hardware comparison, I'm guessing that one of them might fit two unrolled miners for a total speed of around 240 Mhash/s?