> We have described a high-precision and scalable analogue matrix equation solver. The solver involves low-precision matrix operations, which are suited well to RRAM-based computing. The matrix operations were implemented with a foundry-developed 40-nm 1T1R RRAM array with 3-bit resolution. Bit-slicing was used to guarantee the high preci- sion. Scalability was addressed through the BlockAMC algorithm, which was experimentally demonstrated. A 16 × 16 matrix inversion problem was solved with the BlockAMC algorithm with 24-bit fixed-point preci- sion. The analogue solver was also applied to the detection process in massive MIMO systems and showed identical BER performance within only three iterative cycles compared with digital counterparts for 128 × 8 systems with 256-QAM modulation.
For over a decade, "Mythic AI" was making accelerator chips with analog multipliers based on research by Laura Fick and coworkers. They raised $165M and produced actual hardware, but at the end of 2022 have almost gone bankrupt and since then there has been very little heard from them.
Much earlier, the legendary chip designers Federico Faggin and Carver Mead founded Synaptics with an idea to make neuromorphic chips which would be fast and power efficient by harnessing analog computation. Carver Mead published a book on that in 1989: "Analog VLSI and Neural Systems", but making working chips turned to be too hard, and Synaptics successfully pivoted to touchpads and later many other types of hardware.
Of course, the concept can be traced to an even older and still more legendary Frank Rosenblatt's "Perceptron" -- the original machine learning system from 1950s. It implemented the weights of the neural network as variable resistors that were adjusted by little motors during training. Multiplication was simply input voltage times conductivity of the resistor producing the current -- which is what all the newer system are also trying to use.
Travis Blalock Oral History https://www.youtube.com/watch?v=wmqa9XJED-Q https://archive.computerhistory.org/resources/access/text/20...:
"each array element had nearest neighbor connectivity so you would calculate nine correlations, an autocorrelation and eight cross-correlations, with each of your eight nearest neighbors, the diagonals and the perpendicular, and then you could interpolate in correlation space where the best fit was."
"And the reason we did difference squared instead of multiplication is because in the analog domain I could implement a difference-squared circuit with six transistors and so I was like “Okay, six transistors. I can’t do multiplication that cheaply so sold, difference squared, that’s how we’re going to do it.”
"little chip running in the 0.8 micron CMOS could do the equivalent operations per second to 1-1/2 giga operations per second and it was doing this for under 200 milliwatts, nothing you could have approached at that time in the digital domain."
Extra Oral History with inventor of the sensor Gary Gordon: https://www.youtube.com/watch?v=TxxoWhCzIeU
I’m not saying that life is analog, DNA is two bits. IMHO life is a mix of Analog & Digital.
https://sites.dartmouth.edu/odame/
Not the same as general purpose training type computations though.
One of the reasons for failure to compete is that actually all computers are physical computers. Therefore digital is still tethered to one of the greatest analog components ever discovered and as a result when you do analog ai you are really competing with the physics of the transistor. The digital computation is the complex icing on the top of an analog cake.