Posts by HwBoffin 17 publicly visible posts • joined 17 Mar 2013
I remember writing a little script to make megahal chat in a P2P network chat room about 2 decades ago...
It was really funny see all the users chatting with it. We admins kew what it was, but other users really had the most interesting conversations with it.
Some people got angry with it, suspecting a troll.
Downside was that after a few weeks the bayesian database got so big that I had to restart it periodically to avoid stalling my work station.
Nowadays isn't mandatory anymore.
Of course, if the engineer is part of the *guild* this both provides protection to the engineer ( his/her work is reviewed, has civil responsibility insurance ), and the customer ( the overall design is validated by a third party, has legal protection from lawsuits in case of faulty design ).
Most public services demanded that any project must be signed by an engineer/architect, so they had at least a minimum level of competence, but now is not longer the case.
From a few years ago, anybody can create its own designs and present them to be approved ( public concurrence venues, vehicles and its modifications, buildings, chemical plants, bridges ....), but unless they've done the same amount ( or better) than a true specialist, it won't get approved.
I'm glad I don't have to battle with that anymore.
Last year I developed a PCIe add on card with a nice FPGA and assorted peripherals, and one of the proofs of concept that I did to show my boss how well it worked was using memory writes from the FPGA to the video card, as would be used by enabling a DMA from the host CPU.
Neither Linux and Windows were aware that I was reading and writing all around the video memory, IO space and the system's DDR RAM.
PCIe is really a true multi host bus without any kind of security. If the root device ennumerates you, you're free to roam and break havoc as you wish.
As someone once told me :
You may price your software up to the point where is just cheaper to change to the alternative.
So yes, the cost of software change isn't only the cost of the money paid to the creator, but the added cost of moving / recreating the data.
And this is why I have this obsession about having my data in an open format.
In a security demo, we were able to sniff the private key of an RSA algorithm fom an ARM processor just sending clear text messages and recording the generated spectrum with an EMI probe connected to a pico scope.
Sending 200 messages and recording the 200 samples ( fs 100MHz, so quite low) allowed us to set data into a matlab script to correlate the signals and obtain the first 24 bits of the key in less than 5 minutes in a mainstream laptop.
Was quite impressive.
Moreover when you can use a 1GHz sampling DSO and use something more powerful to obtain the whole key in a reasonable amount of time.
Albert
Excuse me, please, but you fail to take into account all those devices with the ip stack directly made on silicon. Not to mention those oldies that need a jtag interface to program because they aren't built on top of an os.
Moreover, the cost of upgrading those of them that CAN be upgraded isn't small.
Albert.
Hmmmm ....
It only takes a nerd to offer the wipeout service for all the muggers/pawn shops in the area to render the
security scheme useless.
Wait until some clever hacker offers it over the net ... just install that software in your laptop and, voilà, your laptop becomes apple servers and unbrikes the device.
Let's see how much time takes to the start of such 'commercial wipeout services' ..
Cynical me ?
i'm so sorry to inform you that the basic wave theory classes want their time with you back ....
Metals, as a conductors, impose a B/H field value of 0 at their surface for high enough frequency and a reasonably small value for 0 ....
Remember all those pesky contour settings in the maxwell equations ? Faraday Cages ?
So, no, radio waves won't travel across a conducting metal ... that's where the glass inlays come to.
Albert
One tiny detail ... the acceleration region develops a negative net charge because of the excess electrons not fired with their atoms, but there is a pretty simple solution :
Fire the excess electrons with another beam (an X ray beam, for example, like your old CRT tv).
That way, you can use the electrons to give some really tiny impulse to the craft. More than the impulse obtained, the main advantage will be the ability of not attracting the expelled ions with the spacecraft charge, that would otherwise provide a braking force ....
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