I wanted to come forward and share some of the details about the GRN1 chip that we are making. Obelisk is here to move the space forward, and a part of that is increased transparency around the ASIC design process so that the community can better understand what goes into an ASIC project and make more informed decisions around proof of work. The chip was co-architected between Obelisk and ePIC Blockchain, and ePIC Blockchain (www.epicblockchain.io) led the implementation of the chip.
The Obelisk GRN1 specs have been updated to 150 graphs per second at 800 watts. The first units are on track to begin shipping early October, and the final units are on track to ship in late October. Our specifications are based on a pessimistic interpretation of simulations that are generally +/-10% for speed and +/-30% for power.
Because of NDAs, I can’t share exact information about our design choices. But I can link to public information and speak broadly about the implications. The GRN1 chip is a single-die cuckatoo31 miner. The chip we made has a full 512 MiB of memory on board. Our technology partners have verified that we are within the margins of test, packaging and yield boundaries, and that the final product will be fully viable. Beyond substantially increased speed and efficiency, using a single chip also reduces manufacturing complexity and enables a more reliable final product.
We believe that the most efficient Cuckatoo32 miner is also a single-die chip using today’s technology. And we also believe that the most efficient Cuckatoo33 and Cuckatoo34 miners are single-die chips using today’s technology. We’ve done substantial investigation into the memory capabilities of modern foundries, but before I go further, I want to provide some basic statistics:
According to the above articles, the smallest SRAM cell at TSMC 16nm is 0.074 square micrometers. And at 7nm, the smallest SRAM cell at TSMC is 0.027 square micrometers. The largest chips have over 800 square millimeters of area. If you do the math, this means that a 16nm chip has a maximum theoretical memory size of about 1.3 GiB, and a 7nm chip has a maximum theoretical memory size of about 3.5 GiB.
In practice, you cannot create a 16nm chip with 1.3 GiB of memory. A chip is a lot more than just an array of bits, but in practice at 16nm there is more than enough room to do a full CC31 mining algorithm, including cycle finding. Beyond that, the foundry does have limits to how much memory they can support, and every piece of memory that you add impacts yields. Due to NDA’s, I’m unable to share the maximum amount of memory we believe we could put on a single 16nm die, but I am comfortable saying that it’s more than 512 MiB. Putting this much memory on a single die does impact yields, however the impact is small enough that our chip remains viable. As a process matures, yields improve substantially, and the TSMC 16nm process is quite mature at this point.
At 7nm, we believe that we could do all the way out to Cuckatoo33 without needing to make a 2x time-memory trade-off. To say that again, we are confident that you can make a single-die ASIC to do CC31, CC32, and CC33. We also believe that CC34 is possible, though at this point substantial time-memory trade-offs are required.
Our Cuckatoo31 chip has a very interesting property relative to typical single-die ASICs - the heat signature. A typical highly optimized Bitcoin mining chip produces between 0.3 and 0.5 watts per square millimeter. Because of this heat profile, a typical $1200 miner may cost $1200 per year to operate, primarily due to the cost of electricity. For an American mining on typical consumer electricity rates, that annual cost is more like $2400 per year, meaning that consumers really cannot afford to mine at home.
Our Cuckatoo31 chip has a heat signature that’s less than 0.1 watts per square millimeter. This translates to much lower electricity costs. The same $1200 spent on a mining device results in electricity costs that are closer to $400 per year for a typical mining farm, and $800 per year for a typical consumer. The total cost of ownership gap between a consumer and a professional farm is substantially lower for cuckatoo miners. This is a key distinguisher for the Cuckatoo31 algorithm and a way that Grin stands out.
There’s another very interesting aspect to Cuckatoo31 specifically. When optimizing over total cost of ownership, wafer pricing becomes a lot more important. The primary cost of the machine throughout its lifetime is not electricity, but silicon. 16nm silicon is cheaper and more accessible, which means that 16nm chips are more competitive, and depending on price, potentially even strictly superior.
This is fantastic for competition. The development and tooling costs for 7nm are far higher, and the 7nm technology is a lot more exclusive. These higher costs mean that there is much less room for competition. If 16nm chips are potentially superior, smaller companies can compete with lower initial investment and the competitive environment for Grin will be more vibrant.
At cuckatoo32, 16nm is no longer the ideal node, because the memory takes up too much space and doesn’t leave enough room for all the other elements of a grin miner. Even switching to cuckatoo32 means that new competitors have to be at a more advanced node, which restricts the competitive environment.
The phase-out also has another adverse effect. Manufacturers are forced to choose an algorithm to target. This complicates the game theory. Manufacturers have to choose a specific level to target, and since miners that target lower levels are more competitive (this is just the nature of the hardware and the cost structure), being able to support a higher level means you will not be competitive at the lower levels. This also harms the overall competitive environment, you want the economics and profit models to be as simple and low risk as possible to encourage competition.
I know this information is a lot different than what many people were expecting. Most manufacturers are not up-front about the nature of their hardware, but we really would like to see Grin succeed, and we would like to do so by collaborating with the Grin community and letting them know what’s going on before it happens. We’re hoping to open a dialog between manufacturer and community, and we’re hoping to give the community all the information it needs to make informed decisions about the future of the proof of work ecosystem that protects the consensus layer. At the end of the day, Obelisk wants to see Grin succeed and we believe that being open is the best way to empower the Grin community. We’re looking forward to your thoughts and discussion.