Data Struture and algorithm is everything in computer science!!!!!!!!This is how files are stored and tables like file allocation tables,inodes etc are maintained in computer hard disk.data bases are maintained using different data structures.as u know hard disk or are magnetic materials,u cannot "draw" with pencil or pen on it to maintain data or tables in hard disk...data structure and algorithms is everything to computer science
microprocessor and microcontroller helps u to understand the the working principle of some of the most initial and simple microprocessors like 8085 and 8086..If u understand them u will realize how the different statements of a program are executed and how function calls in programs take place..how they are stored in stack and retrieved when needed to be executed...The subject will also help u to understand the working principle of complex processors of pentium or motorola