Slashdot Mirror
Ask Chuck Moore About 25X, Forth And So On
Chuck Moore is, among other things, a chip designer. His latest design, the 25x, is based on a 5x5 array of X18 microprocessor cores, and could provide 60,000 MIPS with a production cost of about one dollar. And Moore has the chops to back that up: he's been designing tiny, efficient processors for many years. He's also the inventor of the programming language Forth, which has evolved from a miniscule but radically fast language "difficult for a human to read" (according to The Secret Guide) to the even more radical colorForth. How radical? Try "includes own operating system; has own 27-key Dvorak keyboard layout; meaningful color syntax." How's that for starters? Ask below your questions for Chuck about processors and programming (ask all you'd like, but one per post, please) We'll pass the best ones on to him, answers soon to follow.
He also makes unrealistic claims and confuses toy systems with replacements for industry-standard systems.
His processor designs are poorly specified and buggy as hell, and he just kind of glosses over that (and remember to mix in 3 or 4 NOPs between each useful operation to avoid overheating the chip...). His MIP counts are inflated, because his instruction sets approach turing-tarpit level. For example, if you wanted to do 64-bit floating point operations, you'd probably need to consume 40 or 50 machine ops for each addition, never mind more complex operations.
This new chip is going to be completely I/O crippled and I doubt it will ever get past prototype stage.
OKAD is to the VLSI CAD stuff used by people like Intel and AMD as ed is to MS-Word. Sure, it's smaller, cleaner, and in some ways much more powerful, but it's also strange, hard to use, and it doesn't do the same stuff. OKAD couldn't be used to design something like the Athlon, or even something like a 486. It's made to design tiny chips, like Chuck wants to make.
He dismisses a lot of real problems. He claims that software is easy, but never writes anything hard. Everything is non-standard and isolated from the distressfully complicated real world. Basically, he makes it easy by making things nobody but he would want to use.
The machine on my desk can read, interpret, and process thousands of standard data formats, connect to other computers using dozens or hundreds of standard protocols, recompile and run many thousands of legacy programs, and emulate almost every machine more than a few years old. When I want to do high-speed graphics processing, all the slow crappy code gets out of the way and doesn't matter any more. The machine he would replace it with would do none of these things, it would require all new software and would probably cost about the same anyway, after buying the RAM, hard disk (both for the vast amounts of data I want handy, which takes up far more space than code bloat), input devices, and monitor. That is, assuming it wouldn't need costly specialized versions of these.
He's really designing specialized embedded chips, without bothering to specify (or specifying wrongly) what they are good for. A quirky Forth chip with 486-level performance, support for up to 2 megs of DRAM, and video out? What on Earth for? The toy computer in a mouse doesn't do it for me.
And the new one: basically an embedded chip design, with a turing-complete but miniscule set of primitive integer operations, copied 25 times and laid out in a square array. Why, oh, why?!
Do you know what they're talking about using it for? A replacement for PC server clusters! On the grounds that you can fit as many MIPs in one small box! Wow! 60,000 bogoMIPs! Never mind that the chief assets of a server cluster are the hard-drives and RAM...
The I/O specs? Well, you could put an SRAM controller on the edge...
Cache? 256 KWords (18-bit, of all things) off-chip, which must be managed manually. Sold seperately, O/C. Each processor has 384-word on-chip DRAM, into which you must cram your whole program, or stop to load in new instructions whenever you want to do anything else. All "cache" must be managed by code in this tiny space, too since there's no hardware support.
Speed? Multiplication (18-bit) takes 125 operations. Realistically, we're talking under 500 MIPs, before taking into account the I/O problems and the difficulty of writing good parallel code. I'd be utterly shocked if you got more than 50 MFLOPs out of it, after some very careful optimization. Yeah, it's real supercomputer material.
Now it's starting to look like a $1 chip, non?
His Color Forth is very much like the BASICs on early home computers. They also served as both OS and interface. They were about as small, too, and provided essentially the same functionality. They were also tied inextricably to one platform. Hell, even MS got its start doing this stuff.
And yeah, it would suck to be color blind. Whatever he says about using different typefaces, I wouldn't want to distinguish between 8 different kinds of text with "italic", "underlined", "italic-underlined", etc. If it worked decently, he would have used that instead of color in the first place. We're talking about a system designed around his own poor eyesight, which doesn't account for other vision problems, and doesn't provide real advantages for those with good vision. That's typical of his work: exactly what he wants, what nobody else wants.
Yes, almost everything out there is bloated and ugly. The industry could stand to improve a lot. But Chuck Moore doesn't have the answers, in many ways he's just a smart-ass infatuated with some easy answers that don't work in the real world.
On the other hand, Forth is a very nice language. I agree that it should be taught to children while they are learning arithmetic. It's as simple as languages get, and gives you an accurate model of what's going on in the computer (execute the instructions of this word, then this word, then that word...). I see it as just another language, not language/OS/universal interface. It's very, very good for small, isolated systems. Being an extensible language that relies heavily on globals, it's very, very bad for large team-effort software projects.
Basically, read his work, but take everything with a grain of salt.
---
You'd be surprised at the broadband connection available to things crawling around in your hair.