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1  Economy / Goods / Selling TF2 items for BTC on: July 03, 2012, 03:39:47 PM
I am selling TF2 items in exchange for BTC anchored in USD, dictated by the following conversion rates:

  • 2.66 refined metal = 1 key
  • 1 key = 2 USD
  • USD value converted to BTC by current Mt. Gox bid.

This comes down to: 1 ref is $0.75 and 1 scrap metal is $0.0833.  I sell most items as 1 scrap each ("retail" price) but may be willing to do a bulk discount.  If you want, have a look at my inventory.  I don't list keys on that page; right now I have 4.
2  Other / Obsolete (selling) / Selling paintings/drawings for Bitcoin on: June 12, 2011, 11:52:13 PM
Ok, I'm not selling them, but my dad has expressed some interest in selling paintings for BTC.  Samples of his work: paintings, drawings (charcoal, etc.) (click each picture to go to a gallery of that section).  I think he'll be willing to sell prints and some originals, as well as commission pieces.  If y'all like his work and would be interested in buying some, let me know and I'll see what he thinks.
3  Bitcoin / Development & Technical Discussion / Robustly processing transactions from bitcoind on: May 06, 2011, 02:27:22 PM
I've been rolling around several algorithms for processing transactions in a robust way and have had several ideas, none of which were very good.  Last night I talked about them in #bitcoin-dev and got some good feedback, and I think I've arrived at one that will work well and require only one minimal change to bitcoind.  (In fact, I have already made it and tested the patch.)

The problem is how to reconcile transactions received by bitcoind with the state in another database, without even the possibility of missing a transaction or processing the same transaction twice.  This solution takes into account that a previously-processed transaction can be removed from the block chain and re-inserted into another block later, if the bitcoind discovers that another, stronger chain exists.  To support this detection, bitcoind must be modified to include the block hash in listtransactions output.  Let me explain the process.

First, you must have some table where you store processed transactions.  The table should contain bitcoin transaction ID and block ID (hash, not sequence number) columns.  Then, you poll bitcoind periodically like so:

  • Request the last N transactions, where N is an arbitrary number.
  • Walk the returned list backwards (most recent transaction first) looking for transactions that you consider confirmed (1 or 3 or 6 confirmations, or whatever your requirements indicate).  For each transaction:
    • Look up the transaction ID in your transaction table.  If it does not exist, this is a new transaction; process it and insert the transaction ID and block ID into the table.  (Using transactions, of course, to force the processing to be atomic.)
    • If the transaction ID does exist, compare the block hash in your table to the block hash in the transaction returned from bitcoind.  If they match, then you have processed all new transactions and should now terminate/return.  If they do not match, this is a transaction that has been processed already, but has been moved into a new block due to orphaning of the original block you saw the transaction in.  Update the block hash ID in the table and continue processing, since it's possible that a new transaction still exists prior to this one in the block chain.
  • If you reach the beginning of the transaction list then you haven't found any transaction that you've already processed and that has the correct block hash.  Increase N (add something to it or multiply it by something) and start the whole process over.

I believe this to be the simplest process that will correctly account for any changes in the block chain.  If you can see a problem with this algorithm, or a way that it can be simplified (especially if changes to bitcoind aren't necessary) please let me know.
4  Bitcoin / Bitcoin Discussion / Bitcoin on Free Talk Live again on: May 04, 2011, 05:51:49 AM
Yesterday (May 3rd), Bitcoin came up again as a topic of conversation on Free Talk Live.  You can download the show and give a listen if you want.  I called in around 1:20:00 to address Ian's reservations about Bitcoin addresses, which I hope were adequately explained.  Technical details were less important than the general idea, so some statements in my explanation were not technically correct, but I was trying to keep it short and understandable.  Wink

Ian, if you're reading this, thanks for the opportunity to explain Bitcoin just a bit more.  I enjoy talking about things I like, and I had fun on the air.  Maybe I'll call in again sometime to clarify more details about Bitcoin's operation if the subject arises.
5  Economy / Marketplace / [Selling] 60-day WoW game cards, Zynga cards on: April 19, 2011, 04:36:52 PM
I will proxy-purchase the following game/gift cards, for their equivalent price in BTC (based on the current mtgox bid price) plus whatever taxes I pay (7%) and a 5% fee.

I will generally make a trip to purchase them once per week (the fee will help cover the cost of gas).  If the service becomes popular enough, I might keep a few stocked for instant delivery.

By default you will receive the code on the card only, not the physical card.  If you want the physical card mailed to you (U.S. only) please indicate as such when placing your order, and include 0.5 BTC to cover the cost of postage and supplies.  If mailed, the card will arrive with whatever protective measures the card has intact (usually a scratch-off layer covering the code).

I will not issue refunds for unwanted cards, but if the code does not work I will issue you a refund only if my local store issues me a refund.

I would prefer selling to people who have OTC set up so that we can exchange ratings after each transaction, but this is not required.
6  Economy / Marketplace / Offering software development services on: April 15, 2011, 12:41:04 PM
I'd like to offer my services as a software developer.  I'm interested in taking side jobs apart from my regular full-time job, and this seems like a good market to work in.

I can write software for Windows and Linux (not OS X -- I don't have a Mac to test on) and in a variety of programming languages.  Web development is on the table too, but note that I don't do graphic design.  If you give me a design I can make it work though.  Smiley

Desktop/server languages: C# (Windows/.NET, Linux/Mono), C, Java, VB6, Perl

Web languages: (X)HTML/CSS, JavaScript, PHP (vanilla, MODx, Symfony), Perl

I have four years professional experience and have been programming since I was ~10.  No job is too small, but note I have a fairly demanding schedule and so I would prefer jobs that don't need to be done in two calendar weeks.  Smiley  Usually I would like to retain rights to the code, but this is negotiable.

I ask 25BTC/hr (work logs will be recorded) and samples of work are available upon request.  Some of my code is available online (SourceForge, Gitorious).
7  Economy / Marketplace / $15 gift card for BTC? on: April 13, 2011, 11:55:30 AM

I found a $15 VISA gift card sitting around from my motherboard mail-in rebate and was trying to think of what to do with it when I realized -- duh, Bitcoin!

Obviously I'm not going to be selling the card number directly (unless someone wants it, I suppose) but I would be willing to use it to buy a gift card to Amazon or Newegg or whatever else online.  I would prefer to deal with someone who has a highish OTC rating and/or who would be willing to use ClearCoin to send the BTC.

I am requesting the face value of the card, exchanged at whatever the mtgox ask is when we do the deal.
8  Economy / Marketplace / English <-> Spanish translation services on: April 12, 2011, 01:08:23 AM
Hello everyone,

My wife is a recent college graduate (English major, Spanish minor) looking to get into the translation/editing business.  Since this is a difficult industry to break into, she is looking to get some freelance experience.  Since there's really nothing in the local area, we figured the worldwide Bitcoin economy might provide more opportunity.

If you're interested, let me know some job details and we can work something out.  She is open to translating a few sentences up-front if you would like a sample of quality.
9  Bitcoin / Mining software (miners) / Flexible mining proxy on: April 06, 2011, 10:26:05 PM
Edit 2011-05-04: The software has been released! (View post)


Hey all, I'm trying to gauge interest for this.

I've been hacking for about a week and a half on a mining proxy written in PHP using MySQL for the data store.  I've been running my own miners against it with no problems for the last week.  The basic idea is that you can run multiple miners against multiple pools (same or different, it doesn't matter) and miners can fail-over to other pools if something happens to its preferred pool.

Additionally, using the web interface, you can manage pool assignments from any physical location; your miners won't notice that anything has changed when you switch them between pools.  The information on the dashboard can also be used to help determine when a miner goes AWOL.

Here's the more detailed list of how it all works:

  • Multiple pools can be defined.  Pools can be globally enabled/disabled for all workers.
  • Multiple workers can be defined, each with their own credentials to be used against the proxy itself.
  • Each worker can associate with as many pools as you have defined, and can have its own credentials to be used with that pool.  (In other words, you can have worker A and worker B both working slush's pool, but each using their own worker accounts.)
  • Worker-pool associations can be individually enabled/disabled without affecting other workers, or other pools associated with the worker.
  • Worker-pool associations can be ranked by priority.  The highest priority association will be used -- unless that pool is down or not responding, then the next-highest will be tried.
  • All getwork requests are partially logged in the database, and all work submissions are logged as well.  This includes which worker sent the request, which pool ultimately handled the request, and (in the case of work submissions) whether the share was accepted or not.

All this is manageable from a web-based control panel.  Right now the project is not terribly polished -- not well enough for a release anyway -- but the core seems to be working great.  If there is any interest in such a project, I will probably release it under the AGPL.

I'm interested in the views and perspectives of my fellow miners as to whether this project would have any value to the wider community.

Mandatory screenshot:

10  Bitcoin / Mining / C# mining library on: March 23, 2011, 09:19:04 PM
Hey all.

I've started working on a C# mining library.  I've seen the idea tossed around a few times, and as a newer Bitcoin user with a strong background in programming (it's my job after all) I figured I'd dive in.

Three git commits later and I have a working, purely managed implementation optimized a tiny bit by using unsafe code.  It's getting ~200khash/sec on a mostly-idle 2.66Ghz core.  So not great, but not terrible for a JITed language either.  It's mostly an exercise for me, but hopefully the community will have some use for it...

The miner and data source are hidden behind interfaces; I'm trying to make it easy for someone to come along with an OpenTK-based GPU miner, for example, and allow it to be used with my miner with no modifications to the core library.  Or even write a mining routine in C and p/invoke it.  Likewise, it'll be easy for someone to come along and write a data source that doesn't use JSON-RPC if they wanted to, for whatever reason, and have it work with any of the miner libraries installed on the system.  Since the large majority of the expense in terms of computing power isn't getting into the mining routine, but actually running the mining routine, a native or GPU-based miner should see close to zero overhead, even running in a managed environment (.NET or Mono).

Further, since it's a library and managed, it can be easily consumed by other software and should run ~everywhere.  (The managed miner only supports little-endian architectures at this point, but that doesn't mean addin miners won't work on big-endian.)

The source isn't yet released.  I'm hoping to release the git repo in the next week or so, under the MIT license.

Thoughts on this idea are welcome.  Note that, as someone interested in this kind of thing, I'll probably keep writing it even if you all think it's a horribly stupid idea.  Smiley
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