Slashdot is powered by your submissions, so send in your scoop


Forgot your password?

Comment Re:Persistent myth? (Score 2) 705

Um. This has nothing to do with the path separator and everything to do with the C language.

In C, the character '\' is the escape character. That's how you can print newlines ('\n'), tabs ('\t'), and other things. SInce the backslash has a special meaning sometimes, you have to escape it with a backslash if you want one in your string.

To get the string literal "C:\" in your program, you have to declare it as "C:\\" in the C source.

Comment Re:And he destroyed the focus (Score 1) 317

The reflective part of a mirror is behind the glass, so the thickness is realy irrelevant. There is a point in the fact the mirrors are not curved so some misalignment would result. It seems to work well enough though.

Actually, if he's using rear surface mirrors, then the thickness is more important.

Most glass reflects about 5% off each surface, so the energy from the front surface of the glass is not being directed at the same point as that from the read surface - it's off by the thickness of the glass. (actually, it'll be the thickness of the glass times the sine of the angle of incidence, I think)

Additionally, some of the energy gets absorbed by the glass, and the thicker it is, the more energy is absorbed.

Neither of those effects is particularly huge, but they are dependent on the thickness of the glass. Both effects are eliminated by using front surface mirrors instead.

Comment The title is unrelated to the story (Score 1) 498

The title talks about employees using their higher performance machines rather than their work slowpokes.

The story talks about companies changing from using PCs/workstations as the computing devices to using servers with virtual machines and remote access. The actual execution of code is done on the server, so the performance of the remote "terminal" mostly irrelevant. There are benefits to the centralized approach (mainframes, anyone?), but higher performance by using personal speed demon machines isn't one of them.

Comment Re:Can we finally, finally, finally (Score 1) 405

In theory, life on this planet is an absurd idea.


Are you saying that in theory, life is unlikely?

Are you saying that in theory, life is unlikely here?

What theory actually says this?

Think about it: we're on the fringes of the galaxy, out in the of the emptiest, coldest, and darkest part.

Well, no, not really. We're pretty close to a reasonably warm star. Given the evidence, if seems that our distance from that star is more important than its distance to other stars.

If anything, life would be most likely to exist closer to the core.


What theory says that being in an area with higher star density would be more conducive to life?

I can formulate several theories to explain why being close to the "core" is worse:

Too much radiation.

Too much heat.

Too high a density of "renegade" objects (like comets and meteors), preventing a stable ecosystem from forming on a given planet. ...

We're not special...we're the exception.

Well, we don't really know that now, do we? :)

Comment Re:Too small.... (Score 4, Informative) 243

IBM made a much higher resolution display in 2001:

This is a 22", 3840x2400 display. I still wonder why that kind of technology never caught on. I know the IBM displays (and the Viewsonics) were expensive, starting at $17000 or so (the VS was "only" $9000 new), but I had hoped that there might be economies of scale eventually. Sadly, these panels haven't been manufactured for about 5 years. Every once in a while there's a rumor that someone is making a new model, but it never seems to happen.

I'm also wondering just what happened for (almost) everyone to decide that 1080 is enough vertical pixels.

Comment Re:Maybe not the only one (Score 4, Insightful) 289

There is no requirement that a corporation make money, or that if it does that the shareholders get paid any of the profits. There is no requirement that the board of directors be composed of shareholders at all, let alone those with large percentages of the voting shares.

The board of directors and the officers have a fiduciary responsibility to the shareholders. This means that they must use the investment money responsibly, and should actually be trying to earn money for the company and the shareholders. The laws are basically there to prevent someone from starting a company, getting investment money, and then "losing" all of it due to poor decision making (paying themselves all of the investment money as a salary, for example).

Even if there were a requirement to maximize profits, that is a vague phrase. Maximize over what time scale? A financial quarter? A year, a decade, a century ...? You can't spend any money on research if you're maximizing for the quarter, but it sure helps in the 10-100 year time frame. Spending money on clean-up technology is a bit like paying for insurance. Neither is a good investment until something bad happens.

Of course none of this prevents shareholders from suing officers and directors, but that's not because they actually have a good reason to.

Comment Re:Really need open source CAM (Score 3, Interesting) 277

You're right, I splashed the cash and bought.

Mach3 CNC controller

[snip the math and analysis]

The resolution of the machine is irrelevant, it's the tool size that matters. If you have a 1/2" diameter end mill, you cut a 1/2" swath through the material. It makes no difference if you have 0.01 inch resolution or 0.00001 inch resolution, you'll still step over by about 1/2 inch when using that tool.

So you can see how optimised tool paths, and so on are literally god when it comes to CNC.

Yep, for production machining, optimized toolpaths are a very good thing. The common limiting factor for small machines though is spindle horsepower. The machine can only remove so much metal per hour, and that's directly proportional to the spindle horsepower. It varies with many factors (cutter material, cutter coating, cutter speed, coolant/lubricant, etc), but it's the thing that limits the depth of cut you can use for a given end mill. There's also no such thing as an "optimal path". There are many factors that determine what may be optimal in a given situation - surface finish (the look of it), surface roughness, tool life, machine rigidity, and more.

Sure, there are free OS alternatives to the stuff I paid for, but I don't have the time left to live, nor the inclination to pay the electric bill, that using the free OS alternatives requires.

I sure hope you're talking about non-optimal free CAM, because as it happens, the most capable machine controller available (for less than $5000) happens to be the open source one. I only put in the price limit because I hope that the vendors selling the more expensive controllers actually have some better features than EMC2 - I know what you have doesn't.

Comment Re:Really need open source CAM (Score 1) 277

There are some open source CAM programs, but none of them are really good enough to replace something like MasterCAM at this point.

There's a list of programs on the wiki, here:

Incidentally, if you want to help finance the web hosting for this project, and you happen to need web hosting as well, use this link:

Comment Re:Shouldn't the OS handle this? (Score 0, Redundant) 601

It's just the definition of an operating system, that's all.

The OS is there to provide a standardized (for that OS - not necessarily across OSes) interface to hardware resources. This includes memory, disk space, CPU time, and of course user interface hardware.

If there were no OSes, everyone would have to include e.g. filesystem software within any program that wanted to use the disk drive. The whole point of Windows was to insulate the programmer from the hardware - you use the same GDI calls whether you have a Diamond, 3dFX, Number Nine, or Matrox card (back in the old days). The driver and OS insulate the application from the specifics of talking to the hardware.

Video games are a bit of a special case, because they are the most performance-limited applications most people see. For most applications, there should be no need to know anything about the hardware implementation - only its capabilities (resolution, color depth, etc). The OS API should insulate the programmer from having to know the details of the underlying hardware. For specific applications though, where the highest performance is needed, the application needs to just reserve the hardware resources and ask the OS to get out of the way. Databases need this for memory and disk management, and video games need this for graphics hardware. There shouldn't be a need for a browser to get to this level.

Comment Re:...Or an arms race (Score 3, Informative) 646

(most SSD are 2.5", not 3.5")

PCIe "hard drives" already exist.

Here's a 1TB model:
There are others in 250GB, 256GB, and 512GB capacities.

I doubt that the cost goes down much though. The PCIe interface chip isn't free, and neither is the card bracket. The PC board itself is also much larger, and has to be thicker than those used on most hard drives. The cost differences are probably a wash.

Comment Re:How about congress? (Score 2, Insightful) 139

Well yes, that's the point.

It would be better to ban lobbying outright.

A distant second place, and actually better in some ways, is to make public EVERY WORD that lobbyists and elected officials exchange.

I realize that this would affect both supposedly "bad" and supposedly "good" lobbyists equally, and that's just fine with me. Neither should have the opportunity to influence our policymakers the way they do now.

Slashdot Top Deals

A freelance is one who gets paid by the word -- per piece or perhaps. -- Robert Benchley