Hey, russian characters are not listed in the ASCII-List. The ASCII-List is a list where all characters ( a-z and 0-9 and some others.. here is it:
http://www.asciitable.com/) are listed. The pc converts the thing you write into a binary code. E.g. A(capitalized a !) = --->01000001 <--- is binary (you would say: 65 ^^). And if you tipe russian characters(not listed in the ASCII-list) the pc can't find it and give you back the error. Hope i could help =).
We come back to the numer 0100 0001(65 as example --> A, ! we begin at the right side !) the first number is 1, the second 2, the 3rd 4, the 4th 8, the 5th 16. the 6th 32, the 7th 64... and so on. You now the RAM(Random Acess Memory) ?? It is the same... like 16 bit... 32 bit... 64.. 128... 256...