Please create an account to participate in the Slashdot moderation system

 



Forgot your password?
typodupeerror

Comment man rsync. Three different options to combine (Score 1) 151

Rsync can do pretty much whatever you want regarding symlinks. There are three different command line options. Since symlinks may point outside of the directory you're copying, and may be either relative paths or absolute paths, the "right" behavior is situation dependent. Rsync lets you choose what is right for your situation.

Comment PWM signal spec vs actual (Score 4, Informative) 128

A sensor that outputs a PWM signal, or something that accepts it (such as a servo) has a specified allowable range and curve that it COULD use, and an actual range that it DOES use.

Servo controllers nominally output pulses between 1ms (zero position) and 2ms (full rotation). Actual servo models don't exactly conform to this "standard", so you tune your control to the specific model of servo.

Analogously, the DMX protocol standard says that the BREAK is signaled by a pulse of AT LEAST 88 microseconds (and up to one second). Many controllers fail to read the spec carefully try to output exactly 88 microseconds, sometimes falling a bit short. If you program your DMX to work according to the standard, and test it with truly conforming peers, it'll fail to work with the many DMX items that don't quite conform, or are borderline, sometimes falling a couple microseconds short. To have compatibility with "almost compliant" neighbors, DMX outputs can output a 92 microsecond break, and receivers can accept a 84 microsecond break.

I suspect that's what happened here. The third-party parts ALMOST matched the Apple parts. Maybe they were barely complaint to the spec while the Apple parts were well within spec, or maybe the third-party parts were almost compliant. Either way, they didn't work quite the same, so customers saw failures. Apple adjusted it to work within the parameters of the third-party parts.

I highly suspect if you tested MAF sensor or O2 sensor speced with an output range of "up to 0-5V", you'd find some model's actual range is 0.2-4.5V, while another model's actual range might be 0.3-4.7V. Firmware tuned for the first, the OEM model, wouldn't work quite work as well with the second one - even though they both have "0-5V output".

Comment Thanks for that. Still true, though (Score 1) 202

Thanks for that interesting bit of information.

I tried to include a few words in my post to hint I wasn't saying that Fortran was the FIRST high-level language, or necessarily the first practical one, or the maybe the first widely used high level language. It was an example of an early high-level language that was part of a revolution in the field. C compilers weren't the first to do any optimization, and SQL wasn't the first declarative language. As you said, modern C compilers rewrite the code in ways that would have been unimaginable in Fortran's heyday.

> > With C, we got optimizing compilers that totally rewrite the specification

> We didn't.

Technically, we did. With this paycheck, I got gas. I got gas. With my last paycheck, I also got gas. With my paycheck a year ago, I got gas. Still it's true that "with this paycheck, I got gas" ;)

Am I being pedantic? Of course. That's my job. I'm a programmer. Ccompiler->provides_optimizer == true.

Comment That's called a compiler. Fortran 1957 (Score 5, Insightful) 202

> the humans are no longer coders, they will instead be writing specifications for the code

Humans wrote computer code until 1957. In 1957, it became possible to instead write a specification for what the code should DO, writing that specification in a language called Fortran. Then the Fortran compiler wrote the actual machine code.

In 1972 or thereabouts, another high-level specification language came out, called C. With C, we got optimizing compilers that totally rewrite the specification, doing things in a different order, entirely skipping steps that don't end up affecting the result, etc. The optimizing C compiler (ex gcc) writes machine code that ends up with the same result as the specification, but may get there in a totally different way.

In the late 1970s, a new kind of specification language came out. Instead of the programmer saying "generate code to do this, then that, then this", with declarative programming the programming simply specifies the end result:. "All the values must be changed to their inverse", or "output the mean, median, and maximum salary". These are specifications you can declare using the SQL language. We also use declarative specifications to say "all level one headings should end up centered on the page" or "end up with however many thumbnails in each row as will fit". We use CSS to declare these specifications. The systems then figure out the intermediate code and machine code to make that happen.

The future you suggest has been here for 60 years. Most programmers don't write executable machine code and haven't for many years. We write specifications for the compilers, interpreters, and query optimizers that then generate code that's used to generate code which is interpreted by microcode which is run by the CPU.

Heck, since the mid-1970s it hasn't even been NECESSARY for humans to write the compilers. Specify a language and yacc will generate a compiler for it.

Comment Let me know when computers worry about being repla (Score 2) 221

A lot of people worry about being replaced by machines. That's been a concern for a significant portion of the population, since at least the 1600s. What actually gets tossed aside and replaced by a new machine, every few years, is old machines. Yet machines never worry about being replaced. Indeed they don't worry about anything, or have any concept of self at all. Let me know when machines start worrying about being replaced by Machine 2.0 and that's when I'll be worried.

Comment Re:All energy use ends up 100% heat (Score 1) 130

> Not sure what this has to do with the environmental cost in heat of Google's activities.

Well if you're concerned about the environmental impact of generating heat (a reasonable concern), would it not be useful to be able to measure and compare the amount of heat generated? Rather than the obvious approach of measuring heat by temperature rise email etc, is it not simpler to remember that heat out = energy in?

Comment Of you want to avoid Android. More Linux (Debian) (Score 1) 182

The only reasons I can think of, based on the older version I've used, is if you have your own reasons to avoid Android, or you want to run Ubuntu or Debian userland on your phone.

Android seems to do fine on phones - it works well enough that most devices sold in the last few years are Android phones. Obviously some people would prefer an alternative, other than Apple iOS.

Comment It's Linux. Terminal plus a web browser (Score 1) 182

> Is there a viable pocket-sized, battery-powered server that one could carry in order to use "a terminal and a web browser" with a Chromebook?

It's Linux. A terminal is the native interface. What makes it a Chromebook is that rather than a standard server-side install of Linux (no GUI) or standard desktop install (lots of GUI shit I don't use anyway), it has a web browser a couple other things in a small, very efficient GUI. No GUI for partitioning hard drives, no pre-installed solitaire game. Which is fine for me, I don't partition drives in a GUI anyway.

Then you asked if browsing the web works without an internet connection? Huh? No, I don't do a lot of web browsing work without WiFi.

If you want to, you can install as much as you want of the Ubuntu or Debian userland on top of the ChromeOS-provided kernel. I've not seen any need. My work as a programmer / hacker basically uses a text editor in the terminal, ssh, and a browser.

People who have never tried a Chromebook like to say things like "they are for dummies who don't know anything about computers. A power user would never use one.". One guy I've spoken to, whom I consider to be a power user, had this to say about his new Chromebook:

"suspect I'll make this my primary laptop. I tend to like my laptops slightly smaller, but I think I can lug around this 1.5kg monster"

Maybe someone thinks that guy, Linus Torvalds, is a newbie, and doesn't understand the needs of power users like themselves. Okay, fine, lug around something that weighs three times as much and takes six times longer to boot if you want. Linus and I can look at kernel patches on our Chromebooks.

Comment Comfortable to use a keyboard without a desk (Score 4, Informative) 182

The Chromebook works far better for me if there is any appreciable amount of typing involved. Sure, you CAN put a tablet in a case with a little keyboard, but it's not made for that, and it shows. It doesn't sit comfortably in your lap as you type away like the laptop / Chromebook form factor does.

Chromebooks also tend to have much longer battery life.

I mostly use a large Android phone if I'm not working. I couldn't very well do much work on my phone. On a Chromebook I can (mostly I work in a terminal and a web browser). There is definitely a place for a Chromebook. Most of what I do, for work and play, I can do just fine on a Chromebook. The one thing that comes to mind it doesn't work well for is using Microsoft SQL Server Studio.

Comment They kept at modern computer for 21 years (Score 1) 223

> So they tried something, and it didn't work out for them.

They tried mobile and failed and tried again and failed again and tried again and failed again for 21 years before giving up.

Why have they kept trying to get into mobile? Because most computing devices sold today are mobile, the market for corded computers has been falling for several years, and is expected to continue to fall.

> The vast overwhelming majority of all PCs sold at retail come with Windows on them.

In 2011, 365 million PCs were sold. In 2015, 288 million. In 2016, 269 million. When your market is dropping 8% per year, that's not good. It's also not good for Microsoft that the percentage of PCs sold with Linux pre-installed increases every year. They are doing okay today - 269 million is a lot less than 365 million, but it's still a lot of computers. Have a look at what that curve looks like 10 years from now, though, as sales keep dropping 10% each year. There's a reason Microsoft is trying to sell Linux on the cloud - it's because they see the curve, they know they won't keep selling Windows on PCs.

Heck, they've stopped even TRYING to sell new versions of Windows, upgrades. In the 1990s people lined up around the block to pay $200 for the latest Windows upgrade. Now nobody buys a new Windows version, literally nobody at all.

Slashdot Top Deals

Vax Vobiscum

Working...