Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Comment: Re:It's finally time (Score 2) 126

by TheRaven64 (#49569393) Attached to: Feds Say It's Time To Cut Back On Fluoride In Drinking Water
There was a study posted on Slashdot about this myth a few years ago. They concluded that Americans care more about their teeth because good dental care is expensive and so is a status symbol. Having few teeth is one of the stereotypes of poor/stupid people in the US. Middle class and aspiring middle class people in the US spend money on their teeth (cosmetically, at least) because if they don't then they look poor. For people in the UK, anyone can afford good dental care (for a while, it was easier for very poor people to because a lot of dentists weren't taking new NHS customers except under duress and people on certain forms of income support had guaranteed treatment), so going to the dentist is just seen as a chore and often slipped down priorities.

Comment: Re:edu-babble (Score 1) 341

by TheRaven64 (#49569341) Attached to: The Future Deconstruction of the K-12 Teacher

Yay for you. You were so smart reading, writing, and doing long division at kindergarten age. If only everyone else was so brilliant.

I was slightly ahead for arithmetic (but not by much), but I was at the very bottom for writing - to the extent that I was the only one having to stay in at break times for extra practice. This was not at a selective school (I started at one aged 7), this was at a school with a full mix of ability.

Its not natural or obvious how to use the three seashells. School is there to teach that.

That's rather my point. My school managed to teach all of us those things, what's wrong with schools in the USA?

Comment: Re:One (Score 1) 118

The hotel with only wired in the room.

I keep a tiny wireless access point in my suitcase for these cases. Even with ethernet on my laptop, my phone and tablet don't have an RJ-45 connector and I don't always want to be using my laptop as an AP. Most hotel networks can't come close to saturating 802.11g, let alone .n.

Comment: Re:This is a response to RISC-V (Score 1) 46

by TheRaven64 (#49568857) Attached to: Imagination To Release Open MIPS Design To Academia

I'm moderately associated with RISC V (the lowRISC people are upstairs and I'm in the acknowledgements section of the RISC V spec). The main drawback of RISC V currently is the lack of software. Krste claims that the cost of the software ecosystem for RISC V will be around a billion dollars. My friends at ARM think that he's underestimated that by at least a factor of two. I had a student working on RISC V this year (using the BlueSpec in-order implementation) and the state of the LLVM toolchain is a joke - it's several man-years of work away from basic functional correctness (he had to fix a number of bugs to get simple benchmarks to work), getting it to be as performant as ARM (or even MIPS) is a lot further out.

MIPS ought to have a big advantage there, but they've squandered it. MIPSr6 is actually quite a nice ISA (I like it more than RISC V), but it is not backwards compatible with MIPS I-V or MIPSr1-5 (yes, those are different. Just go with it), so they lose all of their software ecosystem.

Comment: Re:AGP not working with SMP (Score 1) 224

by TheRaven64 (#49568765) Attached to: Linux 4.1 Bringing Many Changes, But No KDBUS
Sadly, both processors lost to the dust, in the end. Back around 2005, there were a lot of people who couldn't spell dual though, and 'duel processor' machines were going for about half what people were paying people who could spell for 'dual processor' machines on eBay. It was an object lesson in the financial value of learning to spell...

Comment: Re:This is a response to RISC-V (Score 1) 46

by TheRaven64 (#49567743) Attached to: Imagination To Release Open MIPS Design To Academia
lowRISC is cool, but it's not that useful for universities. For research (and teaching), FPGAs are much more useful because of the short turn-around. It takes me about 1-2 hours to go from making changes to our processor to finishing the boot of an OS on the FPGA and doesn't require anyone else's input (unless there are bugs, then some help is often useful!). The cycle for getting a chip fabbed is a much longer process, usually requiring a small team and a lot of money.

Comment: Re:It's marketting, not "open source". (Score 1) 46

by TheRaven64 (#49567731) Attached to: Imagination To Release Open MIPS Design To Academia
If you want a MIPS implementation that you can run in an FPGA, then we've built one and released it under an Apache-style license (not exactly the Apache license, because the Apache license says 'the software' in a lot of places). It's an implementation of a version of the (64-bit) MIPS ISA that is over 20 years old, so any relevant patents have expired. We've been using this in teaching for a couple of years (one exercise is to replace the branch predictor, for example). It's written in a high-level HDL, so more amenable to research and teaching uses, because the code is easy to make invasive changes to.

Comment: Re:OpenRISC (Score 2) 46

by TheRaven64 (#49567715) Attached to: Imagination To Release Open MIPS Design To Academia

It's not clear what version of the MIPS ISA they're implementing (the article I read just said MIPS32, which covers a whole range of things). It sounds like it's MIPS32r6, which is not backwards compatible with any previous MIPS version. The only value of MIPS over something like RISC V (which is increasingly the standard ISA for computer architecture research) is that there's a large body of existing software for it, so you can do real evaluation.

We've done a clean-room reimplementation of MIPS III (R4K compatible) implementation in BlueSpec, which is a high-level HDL. MIPS III and the R4K are over 20 years old, so any architecture-specific patents will have expired. In comparison, this core is only 32-bit (really not interesting for research) and is written in a low-level HDL (making the kind of invasive changes that you want to do in research difficult), and is an ISA that has very little software support.

Comment: Re:Z80 was in TRS-80 (Score 1) 118

by TheRaven64 (#49567627) Attached to: When Exxon Wanted To Be a Personal Computing Revolutionary

Any suggestions on that FPGA board?

We use the Terasic DE4 for most things, but it's insanely expensive - definitely only a board to use if someone else is paying. The SoCKit is quite nice - much cheaper and has a dual-core ARM board. We've ported FreeBSD to the ARM (adding devices for programming the FPGA) and our MIPS-compatible softcore to the FPGA, with virtio communicating between the two, which makes it easy to play with heterogeneous multicore. It's mainly intended for prototyping accelerator cores and there's a fast cache-coherent interconnect between the ARM cores and the FPGA so it's quite a nice platform to play with if you want to try and offload computation to the FPGA. It's a fairly small FPGA by modern standards, but still big enough for our CPU, which is a 6-stage in-order pipeline with caches, TLB, branch predictor and so on.

Comment: Re:What we are seeing is ... (Score 1) 337

by TheRaven64 (#49567583) Attached to: Google Insiders Talk About Why Google+ Failed
It wasn't like that when they started. For one thing, the ads were just how they made money, the search was their core business and they did change web search considerably. I also remember that Google ads were quite disruptive. They only accepted plain text adverts and they used the contents of the page to identify relevant ads. This meant that, unlike their competitors, their ads were both relevant (I'm looking at a page about X, therefore I'm probably interested in buying X) and non-obtrusive. Now they try to personalise the ads (just because I was interested in X last week doesn't mean that I'm interested in buying X now, sorry) and they have annoying video ads.

The moving cursor writes, and having written, blinks on.