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

 



Forgot your password?
typodupeerror
×

Comment The original 68000 interrupts were inadequate (Score 1) 147

The original 68000 was almost there for running a real multi-tasking OS. But, it didn't save enough state on the stack during an interrupt. You couldn't guarantee restoring a process's exact state when returning from an interrupt. I heard stories of designs that used two 68000s where one was running one step behind the other. I don't know how true they were. I see on the wikipedia that Motorola fixed that with the 68010 in 1982 and that's when the 68008 came out. So maybe the 68008 doesn't have that problem.

Comment Re:In theory (Score 1) 130

Hmmm, I really like that saying, but I learned it as
"In theory, theory and practice are the same; in practice, they're different." It might even be a Unix fortune. I've seen it attributed to Yogi Berra. (A lot of things are attributed to Yogi Berra by the way, "Deja Vu all over again" is another one.)

In my day (and I'm old enough to have actually seen Yogi Berra play, though he was in the outfield by then), computers were not that common, so going to school was a place to have access to a computer. I did notice that by the 1990s, employers would give you some kind of test to make sure you weren't a fraud during the job interview, no matter what your resume said.

Comment Re:Thinking back late 70's Algol, SNOBOL etc (Score 1) 547

I was a CS major in the late 70s too. We learned to program at least a smattering of Norwegian University Algol on our Univac 1106, as well as SNOBOL (StriNg Oriented and symBOlic Language), APL and something called XL6 (a 'list processing language' so obscure it's not even in the wikipedia, but I'm pretty sure I got the name right.) In other classes I learned some specialty languages, Dynamo (Dynamic Models) and GPSS (General Purpose Simulation System).

Whatever happened to Algol anyway?

As I recall, SNOBOL was actually pretty cool, sort of like Pearl in that you could learn to do some useful things very quickly in it. I don't know that the code was all that readable even to the coder after 3 weeks though, since I never had to look at my code 3 weeks later. And I think even the professor who taught it complained about some of the choices for characters to use as operators. Still, I have this lingering feeling that somehow SNOBOL was a language that was unfairly passed over, maybe because of the comical name.

Comment Is it really the same as incandescence? (Score 1) 243

As I understand it, our eyes can differentiate the frequencies of visible light into the colors of the rainbow, but the rainbow is a continuum frequencies. There's not just one frequency that's perceived as 'red' for instance, but rather a band of frequencies perceived as 'red'. So, does the 'white' light from these newfangled things produce one red frequency, one green, and one blue, or is there a band of frequencies, such as you get from incandescence? And if there isn't a band of frequencies, will it matter to our eyes?

Comment Re:Why do people still care about C++ for kernel d (Score 1) 365

Full disclosure: I have lots of experience with C and almost no experience with C++. (I started to learn C++ but I was suspicious of its complexity. At least, that's what I tell myself, but maybe I was just lazy or too old to learn new tricks. Anyhow, I didn't learn it.)

"Every sufficiently large C project re-invents key portions of C++, poorly."

I have to wonder if that is because every sufficiently large C project is going to have C++ programmers in it who are 'thinking' in C++, and if it was team just of guys like me we would be doing things strictly the 'C' way.

(Incidentally, I realize that C has lots of faults. That's why I'm intrigued by languages like Golang (aka Go) because Ken Thompson is one of the designers, out to fix the faults of his 1st language.)

Comment Conservation of Momentum (Score 3, Insightful) 470

If you're going to have reaction drive style thrusters for maneuvering, you're going to run out of fuel very quickly, dissipating mass, unless your thrusters are thrusting out little bits of mass at VERY high speed, in which case they could be used as weapons themselves. (Sci Fi writer Larry Niven came up with the idea of a reaction drive as a weapon, google the 'Kzinti Lesson' for more info.)

I think it would be interesting to have space battles where several fighters were somehow connected to each other via some sort of tractor beam, so they maneuvered by transferring momentum between each other instead of dissipating mass into the vastness of space; they might look a bit like bolas circling each other but with quick changes snapping in and out as they went in to battle, or maybe they would be tethered to a mother ship, somewhat like World War II aircraft carrier that sends out figher planes to do the fighting. The mother ship would have enough mass to let the fighters seem to be free to zap around easily.

---
("Cough Cough") I wrote an unpublished Sci Fi Novel (I did send it to a bunch of publishers at the time, over 10 years ago), where interstellar travel used 'draggers'. There was no faster than light travel so it took years and years to go between even nearby stars, (The travelers themselves would be in an accelerated frame of reference so it wouldn't be so long for them.) In the novel it took a long time to set up a system between two solar systems, similar to the way it takes a long time to set up a railway between two cities, but then you could use it very efficiently. A vessel would attach itself to a dragger, and be quickly accelerated (that's the hard part, dealing with the sudden accleration that would flatten everything against the back wall like you were in a super cream separator), the dragger, much more massive than the vessel, would be slowed down some, but then, at the other end, as the dragger wheeled around a star, the vessel would transfer it's momentum back to the dragger and slow down to become part of the other solar system.

The thing about conservation of momentum is that it means the center of mass of a closed system doesn't change. If two solar systems and the draggers going between them were a closed system, then the center of mass would shift as the vessel moved between one and the other, but, if the vessel returned to the original system again, then the original center of mass would be restored, and the energy used to move between them could be recycled, plus there wouldn't be reaction mass being spewed out all over the place.

Comment Is it healthy or unhealthy for society to have ... (Score 2) 275

I'm just wondering if when a society has conspiracy theorists speaking out freely, the 'tin hat' crowd, is that the sign of a healthy society or not.

It's bad I suppose when conspiracy theorists are flat out wrong, but would a repressive government try to silence them or do repressive governments only bother suppressing people who are telling the Truth?

Does it do harm in that when somebody really finds something bad going on people will tend to disbelieve them because of all the flakos (sort of like crying wolf too many times)?

Is there some sort of bell shaped curve of attitude towards what the establishment tells us in that a few people on one end of the curve will believe everything and bury their heads in the sand over any problem (like maybe global warming), and a few on the other end of the curve will leap at anything as a plot, while most people are somewhere in the middle? If there is such a curve, maybe it's characteristics (skew, standard deviation, etc) are what determine the 'health' of the society.

Comment Re:Er? (automatic locale?) (Score 1) 314

Hmmm, it sounds like what's needed is a daemon that queries location from a GPS system as well as time, and automatically adjusts timezone and whatever (would you want it to change language? Seems like that's more of a user thing, and something you only change when you change users). Of course, it would require the system be hooked up to a GPS system, otherwise do things the old-fashioned manual way. There could be an app that puts up a map where you click on the location I suppose, instead of fiddling with configuration files.

I'm an old time unix user (going back to 4.2 BSD days). I like the idea of text configuration files for everything. But I wouldn't mind a front end app that was easier to use than constantly having to look at man pages on the formats of everything. A sort of IDE for all the text based config files the way an IDE is a helper for the text code files of a programming language. (But NOT a binary that bypasses the text configs! Which is what systemd seems to be doing, if I've been reading this right.)

Comment Re:Why attack Java like this? (Score 2) 94

Isn't Python supposed to have suffered from a big revision change? My first thought, when I read about Dr Odersky making revisions is that he would be running into the same problem that Python did. Maybe Scala isn't as widely adopted yet as Pascal was, and he thinks he should fix it now before there would be too big of a flap over it. (Actually, if they're changing Java as I gather they are from the interview, wouldn't that also be a blowback for Java?)

I'm an old timer who has never used any of these new-fangled languages professionally (where new-fangled is anything newer then C), so I'm not trying to editorialize here, just wondering.

Comment Re:It's a question that WAS relevant (Score 1) 161

Back in the 1970s I worked at a computer manufacturer, writing code for their product's instruction set in assembler. The computers were designed and built around AMD2901 bit slices. The hardware guys implemented the instruction sets using microcode and, as the computers got bigger and more complicated some of the instructions got so elaborate that programmers found ways to do an operation faster using a few simpler instructions instead of one complicated one.

Nowadays, with the kind of speedups from using cache memory, branch prediction, and so on, I reckon it could be a whole different ballgame. I suspect though, that proving correctness might become the most important criteria, and simpler would make proving correctness easier.

Slashdot Top Deals

Suggest you just sit there and wait till life gets easier.

Working...