I'm not disagreeing with you. I was meekly trying to point out that this type of argumentation keeps reappearing in the Bitcoin millieu: the turtle is getting too big: replace it with stack of smaller turtles.

It all has origin in the forward-delta implementation of Bitcoin and the desire to avoid the hard fork. Until the paradigm shift happens (hard fork to reverse-delta implementation) there will not be much of meaningfull progress; but there will be a lot of activity.

I'm not the first to observe it; I won't be the last. I'll give you the link to my post from about half-a-year ago on this very subject; so you can search your own references using different vocabulary than "forward-delta" and "reverse-delta".

https://bitcointalk.org/index.php?topic=87763.msg965877#msg965877

Now you traded "nearly infinite storage" problem with "nearly infinite bandwidth" problem. Your distributed storage scheme would need a protocol that is resistant to the common exploit: pretend to have block X; but stall (or disappear) when someone asks for it.

It is turtles all the way down, I tell y'all.

Thanks. I don't mind that it spews everything at TRACE level, but I do mind that I cannot redirect and grep/tee/tail through it (on Windows it would be findstr.exe and tailf.exe). If the "no stdout redirection" is not easily fixable then at least make the log file a complete log not "everything less than INFO" log. Thanks again and good night (or good morning.)

"testnet3 memdb" failed 4 times in a row with the same IRC problem.

"production leveldb" starts, but spews too fast to really understand what's going on.

Attempting redirection of standard output gives 'Exception in thread "main" java.io.IOException: unable to obtain console' and exits.

May I also have one suggestion: configure the program to default to "-nolisten", because it pops up the firewall configuration dialog first time it is being run. I let it have the firewall exception enabled, but I would really prefer if the program didn't ask for it first time.

Thanks. It seems safe enough to run. So I tried "testnet3 memdb". It cannot bootstrap itself off the IRC on a machine with a real dual stack IPv4 + IPv6. I think this bug exists in the Satoshi's code too, I just start Satoshi with -noirc. I killed it because the error that keeps scrolling is "Peer connector IRC receive ERROR :Trying to reconnect too fast.". I don't want to DoS anybody's IRC servers.

It clearly shows in the manifest: requestedExecutionLevel="requireAdministrator". Please post something that 7-zip could open before installation.

Why is it asking for Administrator privileges? Can you post a plain archive?

I never had any of the SLX150 boards that were used in those projects. I built some of them with minor changes on VLX240; but I don't recall which ones. This design is very flexible: you can roll the hashers by increasing CONFIG_LOOP_LOG2 parameter until it fits in your Spartan. You shouldn't worry about warnings; there is no way to completely shut them down in ISE even for a perfect design.

This project isn't friendly for simulation. The I/O protocol would need to be changed to give beginning and end of the nonce range to search. Otherwise simulating the search through the 2^32 nonce values just takes too much real time.

[Author unknown to me, I think this is an old USENET joke]

Yesterday, I helped my mother-in-law get set up on email for the first time. She got frustrated from time to time. Upon reflection, I decided that frustration was perfectly understandable. Imagine trying to learn to write a letter for the first time …
 
Me: Ok, to write a letter, the first thing you need is a piece of paper and a pen.
 
Tarzan: What are those?
 
Me: Paper is flat stuff that is made from tree pulp, sort of like a very small blackboard. Pens are sticks that write, sort of like chalk but smaller and in darker colors.
 
Tarzan: Is this paper?
 
Me: Ah, yes, that is paper, but you dont want to write a letter on that, thats my paycheck.
 
Tarzan: Why cant I use this?
 
Me: Well, thats a representation of money that I … uh, never mind. Just dont write on that. Look, heres a piece of paper that you can write on.
 
Tarzan: What about a pen?
 
Me: Pens are like little sticks. Do you see anything on this desk that
 looks
 like a little stick? Uh, no, thats a ruler. Rulers are for measuring things. Uh, no, thats a toothpick, its for cleaning teeth, I dont know why its on my desk. Look, heres a pen.
 
Tarzan: That doesnt look like a little stick! Its grey. Little sticks are brown.
 
Me: I meant little stick metaphorically. Just use this. Uh, you have to take the cap off first. Ok, now write Dear Mom on the paper. Wait, you want to rotate the paper so that the short side is at the top and the long side comes towards you.
 
Tarzan: Why?
 
Me: Well, thats just how its done. I suppose you could do it the other way, but it would look a little funny. Ok, now write Dear Mom on the – oh, no, at the top. Well, never mind, we can just throw this one away and start over. Thats right, Dear Mom at the top. Then the rest of the letter.
 
Tarzan: Ok, Ive finished the letter! Can we go hunting now?
 
Me: Well, you arent really done. I mean, you are done with the letter, but now you have to send it. You need to put the letter in an envelope next. An envelope is a piece of paper that is all folded up to hide and protect the letter. Uh, no, put my paycheck down, we dont want to fold it into an envelope.
 
Tarzan: Wouldnt that work?
 
Me: Well, yeah, it would *work*, but it isnt the best way to do it, and besides, I want to keep my paycheck. Look, just put your letter into this envelope here.
 
Tarzan: It wont fit.
 
Me: Yeah, you have to fold it first. Um, it will work better if you fold it into thirds. No, the other way. There you go, now put it in the envelope. Good. Now seal the envelope by licking the paper here and folding it over.
 
Tarzan: You *must* be joking!
 
Me: No, really, thats how you seal the envelope. Look, if you dont want to lick it, you could get a little sponge and dish of water and use the sponge to wet the envelope flap.
 
Tarzan: Ill just go dunk it in the creek then.
 
Me: NO! Sorry, I didnt mean to yell. Look, Ill show you, *I* will lick it for you. See? Easy.
 
Tarzan: Ok, now can we go hunting?
 
Me: No, not yet, we still need to address the mail so that the postman knows who should get the envelope. So on the envelope, write Lady Greystoke – nonono over here. Well, never mind, we can get a new envelope for it. Ill take it out of the old one for you. Ok, heres a new envelope for you, see if you can put it in – thats good – and seal it.
 
Tarzan: I cut my tongue!
 
Me: Ooops. It does take a little getting used to. Ok, now write Lady Greystoke right here. Good! Ok, now we need to look up her address in the address book. This is my address book, and youll have to make your own address book and fill it in with addresses.
 
Tarzan: How will I know what peoples addresses are?
 
Me: Youll just ask them for their address.
 
Tarzan: How can I ask them if I cant write to them?
 
Me: You have to ask them some other way, like when you see them in person.
 
Tarzan: Why cant I just get a big book with everybodys address in it?
 
Me: Well, there are five billion people in the world, so it would be an awfully big book, plus people move all the time, plus some people wouldnt want their address in the book. Look, trust me, it works. Youll get peoples addresses. Ok, so underneath her name, write her address. Uh, you put the street address on its own line, then the city and state and ZIP code.
 
Tarzan: Whats a ZIP code?
 
Me: Dont worry about it, just do it.
 
Tarzan: Hmmpf. It would be a lot easier if I could just put Mom. Ok, its
 addressed. NOW can we go hunting?
 
Me: Hold your horses. You need to put your return address in the upper left-hand corner of the envelope.
 
Tarzan: Whats my return address?
 
Me: Its how people can contact you. Your landlord should have given you a piece of paper with your address on it. Yeah, that looks right, now copy that to the upper left corner. Upper LEFT corner. Good. Ack! My desk! Put the cap back on!
 
Tarzan: Huh?
 
Me: Its very important that you put the cap back on the pen so that the ink from the pen doesnt get all over everything. Ok, now we have to put a stamp on the envelope, which is a way of paying for the delivery. You need a 32-cent stamp. Never mind why. You need to put it in the upper right hand corner, no, right-side up – so the 32 is right-side up. No, it wont stay by itself, you have to lick it.
 
Tarzan: Im not licking anything else, I cut my tongue last time.
 
Me: Oh, all right. Ill lick it for you this time. Tomorrow you can go buy a different kind of stamps that you dont have to lick.
 
Tarzan: How many different types of stamps are there?
 
Me: Well, theres stamps you lick and self-adhesive stamps, and different denominations of stamps, oh, and there are stamps from other countries but you cant use them.
 
Tarzan: Why not?
 
Me: Because our government doesnt recognize those stamps. And we cant use our stamps in other countries.
 
Tarzan: So do I have to use two different stamps if I send something to another country?
 
Me: No, theres an agreement with other countries that they will deliver mail with our stamps if they come from outside the country.
 
Tarzan: So why cant we use other countries stamps inside our country?
 
Me: They just wont, leave it be.
 
Tarzan: Ok, Im going hunting now.
 
Me: Just a minute, just a minute! How do you think the letter is going to get to your mother? Did you think it was just going to magically leap from the desk and get to her? We need to take it somewhere that the Post Office can find it.
 
Tarzan: How about under my pillow?
 
Me: Dont be smart with me, young man. We need to take it and either put it in the mailbox or take it down to the post office.
 
Tarzan: Isnt the mailbox where mail comes *in*?
 
Me: Yes, but the postman will take it out of the mailbox and take it down to the post office if it is already there.
 
Tarzan: Does that mean that if I dont take my incoming mail out of my mailbox by the time the mailman comes again, hell take all my mail away?
 
Me: No, it doesnt work like that. Look, it just works, ok? Just go put it in the mailbox, Im tired of arguing with you. Then go play in the jungle or whatever, just leave me alone.
 
Tarzan: *Sigh* Letter-writing is *hard*!

The production mining software changes too rapidly for me to understand. You'll probably have to look at some previous version of CGminer or BFGminer, when they were still using serial ports instead of raw USB devices.

Besides, the above software is just too complex.

Start with something simple like ZTEX's miner or jgarzik's/pooler's cpuminer. Or hack out the signcryption out of eldentyrell's miner working through the JTAG taps. You'll initially want to mine on the CPU in parallel to be able to quicky compare the output from your FPGA with known good results from another source.

I think it is too complex and would require soldering. If soldering is acceptable then just solder in any USB-RS232 serial cable.

In my limited experience UDP broadcast over Ethernet would be easier, simpler to debug and use less logic resources than instantiating some USB device core.

Personally, I would use external USB-serial cable connected with 3 bent paper-clips to the appropriate header. Looks hilariously ugly, but works quite reliably. All my desktop machines have serial ports, either on the motherboard or expansion board, because I haven't yet met a device I couldn't tap some UART via bent paper clips or wires wrapped around needles or by hacking some cables.

Edit: I suddenly realised that the above may be read by some absolute beginners. In that case: please remember to watch the voltages. RS-232 default voltages may fry your expensive development kit if improperly connected. Be mindful of that. Cheapest multimeter and RS-232 - TTL level shifter is all you need to avoid releasing the expensive magic smoke from your FPGA.

It has two USB ports, but in a really sucky configuration. One is FTDI and one Cypress; and they cannot be operated at the same time. FTDI is used almost exclusively because it is the easiest supported way to tap JTAG.

There are some serial-over-JTAG drivers available in the NIOS II development kit, so it is doable. But it is a great PITA. Or one could use external JTAG, but this is also a PITA.

Pretty close to a complete communications blackout. Vast majority of fiber optic links are synchronous with the clocks synchronized off of the GPS (or equivalents). If you disable GPS the clocks will drift off in less than a day and the communication will cease. Obviously rich countires have access to multiple precise atomic clocks (cesium, rubidium) and will be able to restore operation of some most critical fiber-optic links. Poorer countries will have to make do with the old radio-stabilized quartz oscillators.

The quickest to fail will be all CDMA carriers (Verizon,Sprint,etc.) because of high required timing precision. GSM carriers (ATT,T-Mobile) will fare better. Various 4G and 3G schemes will fail even faster, but almost all wireless cariers have the above older systems as a backup.

The old style T1/T3 connections (E1/E3 in Europe) will last the longest because they operate plesiochronously.

Afterwards there will be a great amount of energy spent to fix this vulnerability. But the current situation is as described: GPS stabilized clocks are everywhere.

http://www.chronos.co.uk/files/pdfs/wps/Dependency_of_Comms_on_PNT_Technology.pdf

I sincerely wish you good luck, but this project isn't a good starting assignment for a beginner. The competitive motivation element (bounties, etc.) is already almost gone. What you have now is just a combination of workarounds for the deficiences in the Xilinx toolchain; e.g. the use of 512-bit vectors where 16-element array of 32-bit vectors would produce much cleaner code. This skill has a value now, but Xilinx will eventually fix it in some future release and the skill would start to look cargo-cult-ey.

Also, in your past experience, how often have you faced a problem where you could drop half of the valid results and the project would still appear to work and be valuable?

I'm not trying to discourage you at all from working on a miner, just set yourself appropriate goals; e.g. use a comm protocol with CRC so you'll know the actual BERT of your transport.

You can also restore the competitive element for yourself and make a first Litecoin FPGA hasher.

Again: good luck.

I know that the above was meant to be a joke, but it helps to explain some salient choices that the designer has to make.

Most of the FPGA designers for Bitcoin hashing used the XC6SLX150 chip that has about 150k "gates" and costs about $200.

hardcore-fs is working on XC5VLX110T chip that has about 110k "gates" and costs about $2000.

So where's the catch? Spartan-6 has much less "wires" than Virtex-5, the designs on Spartan-6 are quite oftern routing-constrained: there is enough "gates", but not enough "wires" to connect them. And even if there is enough "wires" then the gate interconnections may be longer and slower than in a design that uses less "gates".

Check out the extreme example of the routing-resource limitation: eldentyrell started working on his "hand-placed, auto-routed" design in October'11. He complained about auto-routing failing and being forced to hand-route until about March'12 when he disclosed that he started using DSP slices for some adders to relieve the congestion of the routing for the general-purpose SLICEs.

https://bitcointalk.org/index.php?topic=49971.msg793740#msg793740

The very same conceptual limitations will apply to the ASIC synthesis. One can spend a lot of time optimizing performance for the particular design flow. Or one can accept most of the default choices to optimize the time it takes to start the manufacturing.

Or when there is an exploit, community detects it, patches are produced, executables distributed and all the legitimate transactions are redone.

https://en.bitcoin.it/wiki/Incidents#CVE-2010-5139

I feel that Ripple may come to the rescue here. If not Ripple (the company) exactly then at least Ripple-like mechanical way of finding largest spanning sub-graphs.

Out of all Bitcoin users some meaningfull fraction will not have problem with forgetting anonymity and openly disclosing their credit limits with their counterparties.

If you make an assumption that a "51% attacker" is a highly concentrated entity with relatively little history of previous transactions with the rest of the network then it should be a relatively simple graph search operation to isolate him/her. The "remaining" network will be just 49%, but intensely interconnected and with longer history.

On the other hand, if you cannot make the above assumption that the "51% attacker" is highly concentrated then you've may have discovered a genuine grass-roots movement. I would understand such situation as a revolt against the obstructionism from the core development team.

To quote Erik Voorhees: "Democracy is the original 51% attack."

I think most of the people worked on the Verilog version, not the VHDL one. I wouldn't be surprised if the VHDL version never implemented correctly on Spartan chips, but maybe on Virtex-es only.

Start your play with the versions that have a top-level ISE project file: *.xise.

Are you trying to learn VHDL knowing Verilog or from scratch?

The overall speed of a pipelined logic design is limited by the speed of the slowest stage. In the design I mentioned the last pipeline stage did what every other stage did plus it did the zero comparator, subtractor and a latch.
I don't think you've ever tried to use Xilinx ISE or something similar. The problem isn't: come up with a different, potentially faster design. The problem is: come up with a working design, the one that the available tools will be capable of synthesizing, and placing/routing sensibly. The overall structure of SHA-2 (which makes every output bit depend on every input bit in each round) is apparently hitting some worst case behavior in the Xilinx toolchain. It takes close to a full day to run a single full implementation. And in many cases the the toolchain either fails to converge to a working implementation or converges to something shamefully inefficient.

On this board 2^256 is frequently thrown around as a number so high that nobody will be able check all of them. Compare this with the work demanded from the Xilinx placing tool: 23038 SLICEs in XC6SLX150 can be permuted in 23028! ways (I'm making a gross simplification of the "place" step) which is about 10^90499. Obviously all digital synthesis tools have to take some heuristic shortcuts through that vast space of available solutions.

So the human art required from the designer is to figuratively take the poor toolchain by the hand an lead it/them to some safe place.

Yeah, I wasn't clear. I was trying to make a distinction between mathematical correctness and ergonomical user-friendliness.

Obviously mathematically all of 2*2 or 2.0*2.00 or 2.00*2.00 (as well as their rational equivalents) are equal. Perhaphs non-obviously to some, but ergonomically there is a great difference. If one represents the results from above as 4, 4.000 & 4.0000; then the number of human-made mistakes or bugs dimishes greatly.

I kinda agree. The Freicon, rational math and TVM discussion should move to the Alternative Coins subforum.