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SQLite's WAL support might alleviate your locking problems.

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I think the Git Parable is an excellent explanation of the underlying git model.

http://tom.preston-werner.com/2009/05/19/the-git-parable.htm...

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Consider using PRAGMA SECURE_DELETE = 1 if you want to make these forensics more difficult/impossible.

https://www.sqlite.org/pragma.html#pragma_secure_delete

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What is the advantage of this over a Raspberry Pi?

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Gigabit ethernet that's not dangling off the USB bus, lots of I/O, a realtime micro that's well integrated into the board's architecture, USB OTG, analog inputs. This board seems much more useful if you need lower latency timing, where the Pi seems more useful if you need a small board to stick somewhere and do a bit of number crunching.

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The page seems to only say 10/100. Is there a correction somewhere else?

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You're right. It looks like they're not using the onboard ethernet controllers for whatever reason, and instead dangling ethernet off of USB. So now I'm grumbly about that because the onboard ethernet is much more powerful.

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I find it sad that RPI managed to suck the 'educational' market because of the price point, when the design is extremly obscure. Unless they planned to turn teenagers into hardware reverse engineer...

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There are several advantages:

- both 5V and 3.3V logic, meaning you can use pretty much any part without level shifters

- analog inputs (which are really lacking on Raspberry Pi if you want to use sensors)

- 4 USB host ports (only the Pi 2 has as much)

- the simplicity of Arduino for electronics, coupled with a Linux for other tasks

On the other hand, I expect it to be more expensive, and probably less powerfull than a Raspberry Pi. It is definitely aimed to big electronics project that requires both a lot of GPIO and a full-fledged OS, for which you would formerly use a board running Linux + an Arduino

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"both 5V and 3.3V logic, meaning you can use pretty much any part without level shifters"

Are you sure about that? It can provide different voltages in different pins, but the ATmega32u4 will work with 5v logic (if it is like the Leonardo, at 16MHz will be 5v), so you're in the same situation really and you won't be able to use a lot of 3.3v logic ICs without a translator.

I can be wrong though and this one operates in a different way, but doubt it.

EDIT: ignore me, the page says it has 3.3v logic pins.

EDIT 2: right! they're provided by the Sitara processor and not the AVR, so I wasn't 100% wrong after all ;)

See: https://github.com/CICCIOSGAMINO/arduino_TRE

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also: 7 hardware PWM outputs (the Pi has one)

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You can sort-of do analog input-output via the audio ports on the pi, right?

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Cool, didn't know that.

Seems like the hardware has to be modified and it only supports 0-1V though: http://raspberrypi.stackexchange.com/questions/8757/using-pi...

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PWM is useful because that can be used to drive servo motors and brushless DC motor controllers and other gadgets. It can't be easily replaced with analog output, e.g. from audio ports. OTOH, audio ports are a lot more useful if you need actual analog output.

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PWM could be done with an op amp, a triangle wave generator, and a handful of discrete components. It's how the front-end of a Class D amp works. Would definitely be more of a pain in the butt than having pwm ports directly, though.

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Pi 1 B+ has 4 USB ports as well.

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Arduino has more digital I/O pins and 6-7 pins that can do analog output (via PWM). This new Arduino has even more pins and can do both 3.3V and 5V logic, though I fail to see the advantage of mixing those up. Overall, Arduino draws lower power too.

In any event, if you're looking for something with more pins, beaglebone black or olinuxino have them.

https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXIno-... (that one has 1GB of RAM, gigabit ethernet and SATA2 capable of running a small laptop HDD off the board's power)

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Two I can think of ... it includes a low cost Atmel microcontroller so it can be used for prototyping low cost/low power usage applications, in the same way as the original Arduino. Its compatible with Arduino shields.

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I dropped and cracked my iPhone 6 for the second time yesterday. The larger size and rounded edges make it much more likely to slip out of my (normal sized adult male) hands. I get one more cheap replacement out of Applecare+. If it happens a third time, I'll just switch back to my iPhone 5.

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The idea of the “hello world” program was promulgated by Kernighan and Ritchie in “The C Programming Language”, and they saw it the way kylec does. Quoting “The C Programming Language, Second Edition”:

“This is the big hurdle; to leap over it you have to be able to create the program text somewhere, compile it successfully, load it, run it, and find out where your output went. With these mechanical details mastered, everything else is comparatively easy.”

(I got rid of my first edition years ago but as I recall it described the purpose of the program pretty much the same way.)

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Thanks for the reference.

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I thought about this too when I read about how the FBI seized Ulbricht's laptop. I decided that a simple string isn't sufficient. You want the loop to be either a conductor or fiber optic, so that the system can detect when the cord is cut (not just when a USB device is pulled out).

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How about a lanyard that has a magnetic connector (like Apple charging ports). So it just a small amount of force to disconnect, but easy to stick back together if you forget it was there when you got up to visit the rest room.

Another thought, what about a little coin-sized watch battery device that does bluetooth low-energy. Press a button it locks your computer (or triple click wipes something, etc).

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You should use the scenario of a pair of strong, well trained soldiers physically holding you or otherwise preventing you from performing actions. So anything requiring being aware that you're being raised then doing something like triple click might not be feasible.

I think a system would need to highly tend towards false positives, giving you a short ~5 second grace period to perform some positive challenge that things are OK.

And if this means that every day you end up accidentally having to reboot and start up Tor, well small price for physical security. But really, you should be far more focused on getting your online opsec right so you don't have to worry about thugs. If they're physically grabbing you it's very likely game over.

One countermeasure would be to find people and pay them anonymously to look like you. That is, proxy through their laptop, maybe even have them do some lightweight writing or chatting. Use their life details to leak things, like about weather or other local goings on. Essentially using them as a canary. If they get tackled, you know it's time to burn everything and hide.

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A lanyard with a magnetic connector doesn't suffice. If the enemy cuts the cord, the magnetic connector won't release and the computer won't know anything has happened.

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If the enemy cuts the cord, the loop of wire in the cord will be cut, and hence the computer will know something has happened.

(i.e. you have a lanyard with a magsafe-like connector with two pins. There's a resistance wire that runs inside the lanyard from the connector, up through the loop, and back to the connector. The computer checks that the resistance remains the same.)

If you want to get fancy, you can embed a RC network in the lanyard and have the computer sweep frequencies measuring reactance.

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The Amazon app lets you subscribe to physical goods (just like you can on the Amazon web site).

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“Despite the seemingly obvious answer—tomb art discovered in the 19th century depicts laborers pouring water in front of a block-hauling team—debate over how the pyramids were built is almost as ancient as the pyramids themselves.”

In other words, people don't read comments. This is why the best practice is to build self-documenting pyramids.

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lol yeah exactly. its quite obvious looking at what they were doing: http://www.osirisnet.net/tombes/el_bersheh/djehoutyhotep/pho...

but it is cute that they 'figured it out with science'.

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Clearer schematic rendition of that image: https://en.wikipedia.org/wiki/File:Colosse-dj%C3%A9houtih%C3...

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I've seen this before and found it compelling. Partly I was interested as I came up with an experiment to look at static friction with and without water present for a high-school physics project many-many years ago.

However, that schematic appears strongly interpretative. In the original image I can't see any ropes [that could just be a bad photo]. Also if the slaves are pulling the sled to the right, why are half of them looking left?

The posture is all wrong for pulling on ropes, whilst the posture of the single person pouring water is more natural.

Would a single water pourer be enough. If not why wouldn't they have used the "stacked" technique they've used elsewhere to show there were more than one? At least there appear to be suppliers bringing water on yokes.

To me the figures to the right of the sled seem more like they're walking backwards and forwards, perhaps they're compressing the sand, but they don't seem to be pulling. Contrary to that the single figure on the far right appear to be holding a rope over their shoulder, which is weird if everyone else is holding it at waist height.

Lastly, what are all the "soldiers" doing at the top? They seem to be carrying beams or statues or somesuch in the original, quite different to the swords[?] in the schematic interpretation.

It would be nice to see a cleaned up processed image of the wall that perhaps had used some microscopic or other capture methods to ascertain pigment missing in blank areas.

Is there a reference for what the text on the original image says? That seems like it would be pretty pertinent to the point at hand? Would this whole system work on sloped sand?

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This one might be more accurate: http://www.cheops-pyramide.ch/image/loehner-seilrolle/djehut...

They're obviously pulling the rope, but since the drawings are out of perspective it looks weird.

There are also three water carriers along with the water pouring guy: http://www.thebookofdays.com/months/sept/images/water_carrie...

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That schematic does look a lot more accurate - wonder if there's an app that does hieroglyphics translation?!?

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I think the schematic is not accurate. Look at the 6th set of two people in the top pulling row. One of them is clearly facing back. This is the same with the 8th such set of two. A lot of the heads in these 4 rows are difficult to make out.

On the other hand the number of people looking back in the schematic is 0, 2, 11 and 8 for each row.

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There was an article on this a while back that Egyptologists had interpreted it as depicting something ceremonial- something like breaking champagne bottles across ships' bows.

Having scientific evidence that wetting the sand ahead of the sledges -could- have eased transport is pretty nice evidence that that's what the picture depicts, but without something corroborating its efficacy, it was just a plausible interpretation.

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Fourth row down, far left, there is a guy standing on the sled pouring blue stuff in front of the sled, with dozens of others pulling the sled he stands on.

My guess is that the number of people in the picture will turn out to be exactly the right number needed to pull a full sized replica of the sled

And thank you HN - obscure reference to Pyramid tomb art, "oh here is a link to the very image, three minutes later."

Gotta love HN !

Edit I expect water pourer was the cushy number right up until the sled got stuck because you poured wrong - whips were probably involved then.

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It showed up on HN at least once before, different article though. Edit: Ah, see comments elsewhere on this page for links. :)

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Pyramids: the first successful use of the waterfall method.

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And last.

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Because despite the top down design, the actual building was bottom up.

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I wouldn't recommend Swift to anyone that's new to the iOS SDK. I answered this question recently on stack overflow (http://stackoverflow.com/a/25751738/77567). Here's what I said:

- Objective-C will be around and supported for a long time. (Apple has a massive amount of Objective-C source code that it's not going to port to Swift any time soon.)

- Almost all iOS tutorials, examples, and books use Objective-C.

- Almost all iOS-specific third-party source code you might want to use is implemented in Objective-C.

- It's easier to use C and C++ libraries from Objective-C than from Swift.

- There are many Objective-C experts you can get help from. There are very few Swift experts.

- The Swift language and its standard library are currently not very well documented.

Stick with Objective-C for now. When you're comfortable with the iOS SDK and Swift is better documented, you can consider learning Swift.

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Apple could dramatically accelerate this process by switching their own new development from ObjC to Swift. The huge amount of legacy code means this couldn't happen overnight, but if Apple is obviously making the switch for their own new development, Swift will have a huge credibility boost. Apple wouldn't be able to abandon it (or let development stall) without hurting themselves. Until Apple puts themselves at a similar degree of risk as other Swift adopters, developers are going to wonder about the wisdom of committing to an Apple-only platform that Apple hasn't committed to.

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