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It forces you to structure your application as tiny communicating processes which you route by hand. You're actually coding quite close to the hardware. When yo
by tern 15y ago
It forces you to structure your application as tiny communicating processes which you route by hand. You're actually coding quite close to the hardware. When you want a process to communicate with another – correct me if I'm wrong somebody – you can only communicate processes that are physically adjacent on the chip and you actually write something like "the one to the left/right". Each process is very small and one of the blogs I looked at was very much about optimizing code-size to fit in such a small place. This results in a situation where if your problem does not easily map to this kind of architecture, then you have no other option.
But the same thing can be said of programming at a low level with a Von Neumann architecture. Such architectures are an exceptionally bad match for what the Green Array (dataflow) architecture is good for, namely highly concurrent applications involving processing flows of data such as sensor networks, computer vision, and all manner of routers.
The way that Von Neumann systems handle this problem is by having high-level programming languages (like C), which gives you some level of abstraction from the hardware so that you can model your program however you like and force it to map to the architecture, even if the problem intrinsically doesn't map well. This is why parallel programming is a hard problem. It's not actually a hard problem (well, it could be intrinsically harder), it's just a hard problem for architectures that are not designed for it. On a Green Arrays chip, parallelism is the most natural thing in the world.
Currently Green Arrays has no equivalent of C, and as I understand, this is unlikely to change as the philosophy of Forth is to stay close to the metal and make that an enjoyable experience. That's probably a good thing actually. it's more efficient to design problems to fit the hardware than to use one architecture for absolutely everything as we've been doing for the past 40 years or whatever (with notable exceptions like the Transputer, the Connection Machine, Xmos XCore chips and FPGA's to a certain extent).
- RodgerTheGreat 15y agoYour description of inter-core communication in the GA144 is on the money. In addition to the challenge of mapping your problem to the grid, you have the interesting problem of initializing all those cores with their programs, since it's only possible to do serial communication with a few cores on the edges of the chip. In one of his recent "fireside chats", Chuck discussed how he first fills the chip with a zigzag pattern of of programs that act as a pipeline and then pumps the desired binary along, replacing the scaffolding backwards toward the serial port he's using. It reminds me a bit of the design of biological systems- not only do you have to write a program, you have to make it self-assemble. If anybody's interested in the GA144, GreenArrays recently put up a series of free self-paced courses about the architecture: http://school.arrayforth.com/ http://school.arrayforth.com/
- msutherl 15y agoThat sounds awesome – reminds me of cellular automata – but also, um, I just can't see Joe Engineer figuring that out. My first thought when I started researching Green Arrays was that this was an amazing idea that I would love to see take off, but their UX and marketing will really get in the way. Not like that have much competition though – the entire microcontroller world is hopelessly obscure with the exception of Arduino and all of the projects that it inspired.
- RodgerTheGreat 15y agoFortunately Chuck's already done the nasty parts and you can (presumably) leverage his upload code if you use GreenArrays' tools, but there's always the possibility that your code will require some very specific sequence of node initialization and you'll have to wade in and do it manually. I agree that this tech will probably never be mainstream. If I had an unlimited supply of free time I would be very tempted to develop some third-party devtools for GA chips- I enjoy programming in Forth and I could get used to the F18 instruction set, but using a custom keyboard layout and ditching my text editors and source control systems in favor of a block editor is pretty hard to swallow.
- dkersten 15y agothe entire microcontroller world is hopelessly obscure with the exception of Arduino and all of the projects that it inspired I dunno, it doesn't seem that bad to me. Cortex-M microcontrollers use the ARM instruction set and seem to be gaining ground. I've personally used PIC24 (the 16bit PIC microcontrollers from Microchip) and various 8bit Atmel ones without using Arduino. The 8bit PIC16 still seems reasonably popular too. Certainly none are as popular or accessible to beginners than Arduino, but is it really hopelessly obscure? Hell, if I can get started with PIC24, then surely anyone can! (Though I do admit I've started doing prototyping on Arduino lately because the wealth of sample code saves tons of time and headaches, while before the PIC24 was my go-to microcontroller. I have used the AT90USB162 and some Atmega micros for some work too and will probably use them much more in the future).
- gruseom 15y ago
- Dn_Ab 15y agoWow that sounds amazing. Thanks for that. I can think of how such an architecture would be useful to many types of Machine Learning algorithms. Especially agent and deep learner type networks, also meta-heuristic approaches. AI is a lot about architecture and I would not be surprised if a breakthrough was built on a machine like this.