Discovering Cryptocurrencies

I recently found myself in the market for a mid-range graphics card and latched onto a previously-opened (hence discounted) GeForce GTX 750 Ti from Newegg. (I purchase all my computer equipment from them. They hate patent trolls, as do I. Unlike me, they actually do something about them.)

The GTX 750 Ti is based on the new Maxwell architecture and per online reviews actually vastly improves on previous generations in terms of cryptocurrency hashing power and efficiency, traditionally the realm of ATI graphics cards. Why? Besides generally having more ALUs, ATI chips implement the important right-rotate operation in silicon, whereas NVIDIA chips don’t. Right-rotate is used extensively in Bitcoin’s proof-of-work function, SHA-256, and by extension in scrypt and scrypt-N, leveraged by alternative coins such as Litecoin and Vertcoin. That means when an ATI chip goes to right-rotate by 6, it takes one clock-cycle to complete:

01100101100101001101111001110001 rot 6
= 11000101100101100101001101111001

Meanwhile, most NVIDIA chips have to do two shifts and an addition – three clock cycles:

01100101100101001101111001110001 >> 6
= 00000001100101100101001101111001

01100101100101001101111001110001 << (32-6) = 11000100000000000000000000000000

OR of previous two operations
= 11000101100101100101001101111001

While the GTX 750 Ti probably still doesn’t outperform a similarly-priced ATI card, it at least remedies that right-rotation penalty. I get about 250-260 khash/s out of it when doing scrypt-2048.

I certainly didn’t buy the card for cryptocurrency mining, but it revived my interest in it. I’d last researched it more or less deeply in 2011 and found it fascinating. Now it’s 2014, and things have… changed. For instance:

  • Bitcoin can no longer be profitably mined by CPU or even GPU. Instead arrays of custom chips that compute SHA-256 cheaply (in terms of wattage) are used, and consequently the proof-of-work difficulty has skyrocketed.
  • Tons of alternative coins have emerged: Litecoin, Execoin, Yacoin, GPUCoin, Dogecoin, Vertcoin, Zetacoin, even a Kittehcoin – trading as MEOW on None are fundamentally different from Bitcoin, but they adjust the parameters (proof-of-work function, time between blocks, coin schedule etc.)
  • Everyone mines in pools now, even for the most off-main-street of altcoin. Both centrally run pools and peer-to-peer pools are used.

After dropping back in on this technology after years of absence, I am completely shocked at the advances made in such a short time. The Bitcoin system itself always struck me as very slick, though it may be obvious to someone interested in money supply, currencies and FX markets. But the rapid developments are astounding – two examples:

Mining coins was originally intended to be readily accessible to anyone with a computer. The arms race that ensued led to GPU mining, to people building mining rigs in shoeboxes, to ASIC mining, to data centers renting out their ASIC mining equipment. Finally, has created a secondary market by allowing people to trade hashing power of the mining pool. It’s now possible for traders to speculate on the demand for Bitcoin mining power. In five years, Bitcoin has gone from a white paper to having a derivative market – talk about rapid advancements.

Another fascinating development to me is the many new applications of blockchain technology that have blossomed in just a few of years. Namecoin leverages a blockchain to create a decentralized DNS. ConfessionCoin immortalizes penance done by people who feel guilty about their misdeeds. And on a more serious note, the same concept is being explored with regards to contracts; that is, publishing contracts to a blockchain instead of registering them with a central authority.

Like any nascent technology, cryptocurrencies and their siblings have some problems. Besides the famous Mt. Gox implosion, there are fears of a 51% attack, market crashes and questions about what happens when mining is no longer profitable. But there’s no denying that blockchain technology is truly revolutionary (I don’t say that lightly) and will shape technology and the Internet in the years to come.

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