Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Comment Much More Important: Switch To ECC RAM (Score 1) 183

It's time for laptops, notebooks, phones, desktops, and anything else that needs to be trusted or taken seriously to switch to ECC RAM. As memories get cheaper, larger in total and smaller in geometry, and especially when people use devices at 35,000 feet, there is no excuse for everything (executable code and the content) to be untrustworthy.

Comment FALSE claim in post - not made in the original (Score 1) 990

Once again, a slashdot post quotes an article that ascribes a claim to some other article that made no such claim.
Lesson: Follow the chain of references.

Article quotes: http://phys.org/news/2016-08-electric-vehicles-drivers-percent-road.html
Electric vehicles can meet drivers' needs enough to replace 90 percent of vehicles now on the road.
"Roughly 90 percent of the personal vehicles on the road daily could be replaced by a low-cost electric vehicle available on the market today, even if the cars can only charge overnight,"
But the team found that the vast majority of cars on the road consume no more energy in a day than the battery energy capacity in affordable EVs available today.

FALSE!! The original article http://www.nature.com/articles/nenergy2016112 made NO SUCH CLAIM. The team found that the vast majority of cars DO experience a day when they consume more energy than the battery energy capacity in affordable EVs available today. The original article talked about vehicle-days, not vehicles. Most vehicles only go on extended road trips a small percentage of days during their ownership, but that percentage is not zero.

IN FACT, the original article stated that, "We also find that for the highest-energy days, other vehicle technologies are likely to be needed even as batteries improve and charging infrastructure expands. Car sharing or other means to serve this small number of high-energy days could play an important role in the electrification and decarbonization of transportation."

I may not be able to expect better from phys.org, but I do expect better from people who post on slashdot.org.

Comment A thunk hack (Score 1) 674

I think the following could be considered a thunk hack:

This was an IBM 1130, where integers were 16 bits, but Extended Precision Floats had a 32 bit significand. I wanted to be able to float 32 bit integers. I wrote an EFLOAT(J) function in Assembler. It returned an extended precision FLOAT, but totally ignored the input parameter, except for stepping past its address when returning. Actual usage was, E=EFLOAT(K*L), where E is an extended precision float, and both K and L are integers. I knew that integer multiplication actually produced a 32 bit result spread over two particular registers. EFLOAT floated whatever was in those registers, still lying around from the function call. It totally produced the wrong result if you actually called it with just an integer variable as input.

Would it have been less obtuse to write the function as taking two integers and multiply them inside the function, EMFLOAT(J,K)? Sure, but less fun.

Comment Lots of obvious omissions (Score 1) 397

Out, by some definitions of "gadget":
blacksmith {tongs, bellows, hammer, anvil}. Tongs are listed by the ancient Rabbis (Pirkei Avot, Chapter 5, Mishna 8) as first being made by God, because blacksmiths need a set of tongs to make new ones.

sewing needle
spinning wheel
screwdriver, hammer, pliers

Allowed, by all:
clocks & watches, including sundials
spirit level
lock washer
laser pointer
safety razor
electric shaver
pencils (wooden, mechanical)
pens (fountain, ball point, etc.)
Whiteboard markers
mop, broom, dustpan, vacuum cleaner
sponge, scotchbrite pads
Norelco Philips Carrycorder 150 (Cassette)
ratchet {screw or socket} driver
Vice Grip Pliers
Hand Egg Beater
Coffee Grinder
Coffee Maker {Percolator, French Press, Mr. Coffee, siphon / vacuum}
vegetable peeler
can opener
Slide rule {especially circular}
international power socket adapter (with or without a transformer)

Comment A Corner Cube Reflector sends light back (Score 1) 93

The sensor could be back at the laser location if there is a corner cube reflector at the far end.

Comment Maybe she was "thinking" of Don Herbert,Mr. Wizard (Score 1) 634

Don Herbert, was Bill Nye's professional antecedent. He brought science to children's television from the 1950's (me) through the 1980's (my children). He was a general science and English major at the University of Wisconsin - La Crosse, flew bombers in WWII, and acted in children's programs such as the documentary health series It's Your Life (1949). see https://en.wikipedia.org/wiki/Don_Herbert

As Mr. Wizard ( https://en.wikipedia.org/wiki/Watch_Mr._Wizard ), he was my first science teacher. I saw on his show things that I never saw again in my education (breaking a yard stick with a piece of newspaper) or saw only in graduate school, such as Schlieren Optics. ( https://en.wikipedia.org/wiki/Schlieren )

May the fleas of 10,000 camels pester anyone who speaks ill of either Don Herbert or Bill Nye.

Comment "Make a thing to do what you want done" vs. coding (Score 1) 281

I admit to have read only about 1/4 the responses.

A major challenge in teaching the initial course in any subject is making it fit in the context of what the student already knows and, preferably, cares about.

Do kids want to draw? solve puzzles? mazes? tell stories? animate them? shoot things at other things? play bump'm cars? shoot each other? make real things move? Play hide & seek?

Teach them how to do these things.

Afterwards, give the patterns names and extend their applications. This pattern is called an iteration, (a) over items in a list, (b) with counting, (c) while this condition or until that condition. This is an action routine, with side effects. That is a function, with a result, but no side effects. The other thing is a function with side effects, which in our religion is shunned and considered taboo.

In my high school, in 1967, all sophomores learned FORTRAN, taught by math teachers. The next year, I found it very useful to do my homework for me in analytic geometry and beginning calculus I wrote programs to do binomial expansions, numeric differentiation and integration of functions, and to plot equations ( 0= f(x,y) ). That's what I wanted a computer to do for me.

Over the years, I have used many languages and tools to make a computer do what I needed. This has given me the ability to chose among those I (or my client) had available and already used, or to look for, learn, and use something else more appropriate to the problem domain.

For kids, I highly recommend starting them with the puzzles at https://blockly-games.appspot.com/
(Surprisingly, this site sometimes works better on firefox than chrome.)

When they want to create their own, start with http://snap.berkeley.edu/ . Some of these tools let the user switch views between visual and javascript source code.

My 9 year old grandson completed blockly-games. I bought him a Hummingbird Duo because it supports a progression of programming environments and languages starting with SNAP, which is a natural successor to blockly. See http://www.hummingbirdkit.com/learning/software and http://www.hummingbirdkit.com/learning/tutorials

Comment It depends on how common your name is (Score 1) 289

David Marcus can say what he wants about telephone numbers going away. Linkedin has 350 entries for David Marcus.
When David Smith was my manager, he was one of 22 David Smith's in IBM US. Linkedin now has a total of 22,807 results for David Smith.
The problem isn't having 1 number for a person, it is having home, cell, & work phones; personal & business email; and id's on facebook, whatsap, skype, .....................

Comment "mostly interested in high reliability"== ECC RAM (Score 1) 237

If you are interested in reliability of the results you produce, read on.

If you want trustworthy calculations or documents without occasional random mistakes in content, you need a machine with ECC. See http://www.intel.com/content/dam/www/public/us/en/documents/technology-briefs/workstation-ecc-memory-brief.pdf

Soon to be available:
Lenovo: http://www.anandtech.com/show/9503/lenovo-launches-new-p50-and-p70-mobile-workstations-with-first-mobile-xeon-chips
They do not appear yet on Lenovo's shopping site.

HP: http://www8.hp.com/us/en/hp-search/search.html?nores=true&qt=zbook%20ecc
Results for “zbook ecc” (0) No results found in All HP.com. Please try again.

Nowadays, with very few exceptions, desktop PC's, laptops, notepads, phones and even low end servers all come with RAM that does not check for soft errors at runtime, and usually not even hard errors at power-on or reboot. No parity checking, no Error Correcting Coding (ECC). Most user-class processors, chipsets, motherboards, and BIOS's do not support it.

On these computers, if a random change happens to a bit of code, if you are fortunate, the program crashes. If a random change happens to bits of the kernel, if you are fortunate, the whole OS crashes. If it happens to your application data, well, it isn't what it used to be. Random alterations to a dirty disk buffer in memory will get written out to disk. If it happened to your data, it changed. If it happened to a directory or file system allocation bit map, some spot that is occupied will maybe appear to be free. If it happened to the table of which dirty disk blocks are where in memory, then data blocks on disk will end up with totally content, with the correct content written someplace else or not at all..

Why is it this way? The story goes back 25 years, when clone makers came out with IBM PC clones without parity memory. IBM's and some other company's PC's had parity memory. The good news was that it would catch soft errors. The bad news was that when BIOS caught a parity error interrupt, it cleared the screen, put a Parity Error message on the first line and halted the computer. Unsaved work? too bad. In the middle of a file write, directory or FAT file system update? too bad. Some manufacturers offered a BIOS option to disable that behavior. Enough customers preferred that option that more companies started using non-parity memory. After all, the parity memory bits add another 12.5% to memory cost. Why not be able to offer a lower price for what the customers want? Eventually, even "market driven" IBM started doing the same.

ECC watches for and corrects soft errors when they happen.

For some people, it may be adequate to use a generic laptop to VNC or RDP into a server class machine with ECC for important work.

Comment Not that there was no race. There was. The US won. (Score 1) 295

From all the text in the original item and Forbes blog, there definitely was a race. Several races, in fact. Aryans, Jews, Italians, Mixed-ethnicity Americans, etc, as well as the race for the bomb. Thank God, the Germans did not win, or come close enough to create lots of radioactive material with which to blitz England with dirty bombs and V2's. They might have been set to explode at 150 .. 1000 meters to pollute and require effort to clean up.

Slashdot Top Deals

"Just think of a computer as hardware you can program." -- Nigel de la Tierre