Wednesday, 21 March 2012

Undersea Cables

How do undersea repeaters work? What is the distance between the repeaters? How does a ship that put undersea cables look like? How long can a cable be? The answers are here.

Tuesday, 20 March 2012

Let's Begin: First Math Riddle

Good morning to all my happy (and not so) readers, it took me a while to find a reasonable (or not so) riddle for the first course I'll discuss here. So let's begin with the first math riddle: I lend money from my parents, 100NIS from both of them - 50NIS from my father and 50NIS from my mother, in order to buy a t-shirt for 97NIS. I bought the t-shirt, and got change of 3NIS, while 2NIS I gave to my parents - 1NIS to each of them and 1NIS I kept for myself. Here I tried to calculate the sum of money that was involved in order to know that what I will earn later will be enough, so I started to calculate: the money still I own: 2*49NIS +  the money I returned: 2NIS + the money I had kept for my self: 1NIS = 101NIS.
Where is the mistake?
Imagine there was no 100NIS and 3NIS, but 10,000USD and 2000USD and there was no two parents, but twenty people. The mistake would "cost" me much more if someone would tell me to give just let's say 100.5NIS (and here it would be 11k) to close the deal as a kindly favour for me.

Didn't like the riddle? See one of my favorite riddles Third CS Riddle (short).

Friday, 9 March 2012

Today it's Continuous Blue Screens on My Netbook Lenovo S10

    Looks like a dump file after each blue screen offers a program to be killed - the one that causes all the troubles. I found BlueScreenView wich is supposed to search and show those dump files. I have windows 7 and I read that Daemon Tools can cause it here, but I don't have Daemon Tools so I'll see what it is. By the way, the blue screen is always pixelated so I can't see the problem when it happens.

    I clicked on Google Search in BlueScreenView and it searched for "IRQL_NOT_LESS_OR_EQUAL ntkrnlpa.exe". Looked like I'd have to buy a new RAM or to update some drivers. I chose the later. I ran "sfc /scannow" in DOS... it didn't help much, I got too many unfixable files at C:\Windows\Logs\CBS\CBS.log.

    More and more I'm starting to think about formatting the whole partition (I have Linux with GRUB). The problem with netbook is that there is no a software I can install. Lenovo has the flash drive with the windows on it. I don't. So far I'm getting a blue screen aproximately once a day. 

Something Really Cute for the Weekend

You write your name, they write it everywhere. Check it out:

Wednesday, 7 March 2012


Welcome to the Computer Science blog that will take you all the way towards the degree. I'm a graduating student at the Open University of Israel and I will go through every course in this blog in addition to many other interesting stuff related to Hi Tech and computers. The blog aims to introduce you, the only interested and the very begging students of CS from any university in world to the various contents of the courses through riddles, to wake your curiosity and to bring you some additional material that might interest you as a simple PC or MAC user.

Since the courses at the university are divided into two: math and pure computer science, I will state at titles "Math" or "CS" (i.e Third Math Riddle).

And one more last thing, as I mentioned earlier, the blog targets CS B.A students from all over the world, but since I've studied at the Open University of Israel (OPU), by saying "the university" I will mean the OPU but target any university on the planet.

See also Third Math Riddle - one of my favorites riddles.