Write a love note to your master boot record

Posted at: 3:20am 12th November 2007 by Ben Hardwidge

Inspired by XKCD comic, an expert assembly code programmer writes an app to make your computer greet you with a note when you switch it on

After reading a recent instalment of every stickman’s favourite Web comic, XKCD, in which the punchline involves a guy’s girlfriend messing up his computer by writing a ‘sappy love note’ to his MBR (master boot record), a programmer www.virtualroadside.com has written a program to write a love note to your MBR and display it when you switch on your machine. Not only that, but it also shows the ‘Missing operating system’ message ‘just for fun.’

If you’ve ever had the misfortune to look at a piece of low level assembly code, then you’ll know that it’s the sort of thing that should only be attempted by an elite force of pale-faced programmers in Taiwan. It’s for this reason that virtually nobody knows how to program a BIOS (more on this in Issue 52 of Custom PC, on sale 22 November), and why the programmer of the app, Dustin, created the quiz below to see if you’re qualified to install it yourself:

Quiz:

1. What is the difference between an MBR and a boot sector?
2. What does interrupt 0×19 do?
3. What offset does the partition table start at in an MBR, and how many bytes is each entry?
4. What offset is the “signature” of the MBR located at, and what is it?


Quiz Answers (encoded in ROT13)

1. Obbg frpgbef ner qrsvarq cre cnegvgvba, gurer vf bayl bar (hfrq) ZOE.
2. Vg vf gur vagreehcg pnyyrq gb obbg sebz n qvfx.
3. 0k1OR, fvkgrra olgrf
4. Vg vf ybpngrq ng 0k1sr, naq vf 0k55nn

As Dustin says, ‘don’t use it unless you really know what you’re doing. The number of people that would fit that description is around 0.001% of the population of computer programmers.’ Still, it’s a neat customisation tool that might be worth trying on the old 486 machine that your Dad’s got hidden in the loft.

Via BoingBoing.