Read today

27 May 2015

Micro-disassembly of a DVD read head

15 Jul 2014

Armed with a Phillips screwdriver, a pair of tweezers and a 300x digital microscope, I decided to delve into the innards of this three year old Chinese-built DVD player. What follows are some of the interesting things I found inside.


I’ll be concentrating on the read head (1) below, which slides back and forth along the metal rod (2) as the disc turns:


A alternative tab-less browser design

01 Dec 2013

An attempt at designing an alternative browser UI that does not rely on current metaphors such as tabs, history, back/forward buttons, address bars and bookmarks.


This scheme considers the web to be an ecosystem separate from the operating system and therefore requires its own authentication. All user profile data is encrypted on disk – history, cookies, local storage, saved passwords and user settings. This allows the user to save website passwords and permit authentication cookies more liberally (because his profile password now acts as a gateway between other users and saved data). After logging in, a typical session will not require the user to enter passwords at all (except for new website registrations).



How I finally understood Bitcoin

28 Nov 2013

A plain English explanation of the theory behind Bitcon-like virtual currencies. Some oversimplifications have been made in the interest of clarity and brevity. But if you find outright errors or have suggestions for improvements, let me know!

The perfect currency

Imagine a fantasy society. They have the same exchange problem as us — they can’t barter one tenth of a horse for a mug of beer or half a haircut for a loaf of bread. Our society’s ancestors solved this problem by switching to gold and other precious metals — you can divide it into very tiny units, it doesn’t rot and everybody recognizes its value.

But in this fantasy society, they have alchemy. They can create any metal they want (we’ll get there someday too, through matter transmutation). In this place, a grain of gold is no more valuable than a grain of sand. Yes it’s useful, but nobody will accept it as payment because it’s so abundant. It’s just like you won’t accept air as payment even though it’s technically more valuable to human life than food1.

So what do they do? They devise a type of magic coin and a magic wallet (later we will replace this magic with technology). This type of coin is impossible to copy or forge perfectly. It’s not even possible to create it at will, because then everyone will do it and it’ll be about as valuable as sand again. So it has to have a limited supply. The magic works by creating these coins periodically. Who gets the newly created coins? Everybody. Since this is not a finders-keepers scenario like in gold mining, it’s only fair. Newly generated coins periodically appear in everyone’s wallets. And these coins can be neatly split into smaller coins so that they can be spent in any fraction you want.