Monthly Archives: September 2012

Asterisk For a Small Business (VII)

As we left things last time, we had a nicely organised dial plan that had the minimum of duplicated code, and was essentially a set of tables that mapped endpoints to extensions or queues. Let’s remind ourselves. [internal-extensions] ; Numeric aliases exten => 2100,1,Goto(andyp,1) exten => 2101,1,Goto(wife,1) exten => 2102,1,Goto(handytone1,1) exten => 2103,1,Goto(handytone2,1) exten =>… Read More »

Asterisk For a Small Business (VI)

Last time I showed you how to add voicemail facilities to your incoming lines. We concentrated on the local end, how a single access number could pickup voicemail from different mailboxes depending on the extension it was dialled from. I didn’t discuss the receiving side very much, and simply gave you this template: [external] exten… Read More »

Getting Started With Tor

I’ve heard lots about Tor, and thought it was about time I learned how to use it. I have no actual use for it; but in the same way I have no emails that are really private and yet still use OpenPGP, I like to know how to use the technology that keeps prying eyes… Read More »

Analogue versus Digital

On Radio 4’s PM some time ago, there was some guff talked about music quality. It’s standard guff talked by people who call themselves “audiophiles”, but in fact know absolutely nothing about electricity, signals, or in fact any mathematics whatsoever. They were very vague about it, but in essence the claim was that digital music… Read More »

Blowing a Fuse

I like to use avrdude for programming my AVR’s. It’s got support for pretty much every possible programming method supported by the AVR CPUs and has a good command line interface. A command line interface is very important when you use Makefiles to act as your IDE. Here, for example, is a little bit of… Read More »

Bitcoin Explained (VI)

This is the final part, part VI in my “Bitcoin Explained” series. Details then. Not necessarily relevant for understanding. Bitcoin’s transactions are a little more sophisticated than the paper analogy reveals. Each transaction is itself uniquely identified, and acts as a hub for transferring from any number of arbitrary sources to any number of arbitrary… Read More »

Bitcoin Explained (V)

This is part V in my “Bitcoin Explained” series. At the end of part IV we saw how a signature chain can be used to create an unstealable ownership record; but that a dishonest person in the chain can easily create multiple copies of a valid signature chain. 17283726152 17283726152 I will pay the owner…… Read More »

Bitcoin Explained (IV)

This is part IV in my “Bitcoin Explained” series. At the end of part III we saw that the Bitcoin network’s primary function is to act as a peer to peer timestamping system. That the blocks could, in principle, verify any data its operators wished. The catch of course is that those operators need an… Read More »

Bitcoin Explained (III)

This is part III in my “Bitcoin Explained” series. The problem we left at the end of part II was that while we had a way of constructing a coherent chain of blocks, and of having them verifiably claim an arbitrary level of difficulty of creation; we had no way of deciding how difficult a… Read More »

Bitcoin Explained (II)

This is part II in my “Bitcoin Explained” series. The problem we left at the end of part I was that the construction of a valid chain of payload-storing blocks is trivial (for a computer) to create. For a financial system we want it to not be trivial, we want it to be incredibly hard… Read More »