* The C Programming Language. 2nd Edition. nuff said.

* Learn C++ in 21 days. May seem strange from the title, but this was the book that helped me really grok OO design. It's examples about mammals horses dogs and unicorns (!) have stick to me for ever.

* Digital Computers (this is a greek-only book, publish date was 1979 or something): We had this book for a course at our first year on the University. It introduced everything from transistors to logical gates to flip flops, to more complex circuts to a complete (teaching) ALU to writing ASM for that ALU. Understand everything was a revalation to me.