3 ms·

This is interesting - each node is tiny and can barely do much (mainly RAM constraints). But because they are tiny, you can pack tons of them on a chip/board an

by grogers 16y ago

This is interesting - each node is tiny and can barely do much (mainly RAM constraints). But because they are tiny, you can pack tons of them on a chip/board and coordinate several nodes to do larger work items. Since all actions are asynchronous (as opposed to clocked) you use very little power when you aren't actively doing work, and the minimum amount of time required to actually do the work. I wonder why they settled on 18 bit words though?

Jach 16y ago
From http://www.yosefk.com/blog/my-history-with-forth-stack-machines.html http://www.yosefk.com/blog/my-history-with-forth-stack-machi... : Look at the chips he’s making. 144-core, but the cores (nodes) are tiny - why would you want them big, if you feel that you can do anything with almost no resources? And they use 18-bit words. Presumably under the assumption that 18 bits is a good quantity, not too small, not too large. Then they write an application note about imlpementing the MD5 hash function: "MD5 presents a few problems for programming a Green Arrays device. For one thing it depends on modulo 32 bit addition and rotation. Green Arrays chips deal in 18 bit quantities. For another, MD5 is complicated enough that neither the code nor the set of constants required to implement the algorithm will fit into one or even two or three nodes of a Green Arrays computer." Then they solve these problems by manually implementing 32b addition and splitting the code across nodes. But if MD5 weren’t a standard, you could implement your own hash function without going to all this trouble. In his chip design tools, Chuck Moore naturally did not use the standard equations: "Chuck showed me the equations he was using for transistor models in OKAD and compared them to the SPICE equations that required solving several differential equations. He also showed how he scaled the values to simplify the calculation. It is pretty obvious that he has sped up the inner loop a hundred times by simplifying the calculation. He adds that his calculation is not only faster but more accurate than the standard SPICE equation. He said, 'I originally chose mV for internal units. But using 6400 mV = 4096 units replaces a divide with a shift and requires only 2 multiplies per transistor. ... Even the multiplies are optimized to only step through as many bits of precision as needed.'"

by grogers 16y ago

Jach 16y ago

From http://www.yosefk.com/blog/my-history-with-forth-stack-machines.html http://www.yosefk.com/blog/my-history-with-forth-stack-machi... : Look at the chips he’s making. 144-core, but the cores (nodes) are tiny - why would you want them big, if you feel that you can do anything with almost no resources? And they use 18-bit words. Presumably under the assumption that 18 bits is a good quantity, not too small, not too large. Then they write an application note about imlpementing the MD5 hash function: "MD5 presents a few problems for programming a Green Arrays device. For one thing it depends on modulo 32 bit addition and rotation. Green Arrays chips deal in 18 bit quantities. For another, MD5 is complicated enough that neither the code nor the set of constants required to implement the algorithm will fit into one or even two or three nodes of a Green Arrays computer." Then they solve these problems by manually implementing 32b addition and splitting the code across nodes. But if MD5 weren’t a standard, you could implement your own hash function without going to all this trouble. In his chip design tools, Chuck Moore naturally did not use the standard equations: "Chuck showed me the equations he was using for transistor models in OKAD and compared them to the SPICE equations that required solving several differential equations. He also showed how he scaled the values to simplify the calculation. It is pretty obvious that he has sped up the inner loop a hundred times by simplifying the calculation. He adds that his calculation is not only faster but more accurate than the standard SPICE equation. He said, 'I originally chose mV for internal units. But using 6400 mV = 4096 units replaces a divide with a shift and requires only 2 multiplies per transistor. ... Even the multiplies are optimized to only step through as many bits of precision as needed.'"