CS Fundamentals
200 articles in this topic
File systems and disk scheduling in OS: allocation, directories and seek time
A file system is the operating system's answer to a simple-sounding question: where on the disk does each file's data actually live, and how do we find it again quickly? Disk scheduling is the follow-up: when many read and write requests are queued, in what order should the head service them so the disk arm travels least? The two meet in one place: how the file system scatters a file's blocks decides how far the arm travels to read them back. Both are steady exam scorers.
Memory management in OS: paging and segmentation explained
Memory management is how an operating system decides where each process lives in physical memory and maps program addresses to hardware locations. Correct mapping lets many processes share memory safely; bad mapping wastes space through fragmentation or causes invalid access. Most exam questions reduce to one skill: translating a logical address into a physical one.
CPU scheduling algorithms: FCFS, SJF, Round Robin and priority explained
When several processes are ready to run and there is one CPU, the operating system has to choose who goes next. That choice is CPU scheduling, and the algorithm it uses decides how long each process waits and how responsive the system feels. It is almost entirely mechanical: draw a Gantt chart, read off the completion times, and two subtractions give you everything an exam question asks for. Four processes, four algorithms, and the same two averages come out different every time.
Syntax-directed translation and code optimization in compilers explained
The back end of a compiler is where a parse tree stops being a grammar exercise and starts becoming a program that runs fast. Two ideas carry most of the weight there: syntax-directed translation, which attaches meaning and code to the grammar, and code optimization, which rewrites that code to do the same work with fewer instructions. Both are heavily tested and both reward understanding the mechanics rather than memorising names.
Parsing in Compiler Design: Top-Down and Bottom-Up Explained
Parsing in compiler design for GATE CS: FIRST and FOLLOW sets, LL(1) predictive parsing, LR and SLR shift-reduce, plus a worked parse table and trace.
Lexical Analysis in Compiler Design: Tokens, Patterns and Lexemes Explained
Lexical analysis in compiler design for GATE CS: phases of a compiler, tokens, patterns and lexemes, regex to DFA scanners, input buffering and symbol tables.
Group Theory and Algebraic Structures: Groups, Rings and Fields Explained
Group theory for GATE CS: binary operations, group axioms, abelian and cyclic groups, subgroups, Lagrange's theorem, rings, fields and a worked Zn example.
Propositional and Predicate Logic: Truth Tables, Quantifiers and Inference
Propositional and predicate logic for GATE CS: connectives, truth tables, logical equivalences, quantifiers and negation, plus a worked inference proof.
Set theory and relations: closures, equivalence and partial orders explained
Antisymmetric is not the negation of symmetric, a transitive closure is not finished after one pass, and a Hasse diagram is what is left once you delete every edge transitivity already implies. Set operations, relation properties, closures, equivalence classes and posets, worked for GATE.
Sequential circuits: flip-flops, latches and counters explained
Sequential circuits for GATE: SR, D, JK and T flip-flops, excitation tables, latch versus flip-flop, and a fully worked synchronous counter design example.
Combinational circuits: multiplexers, decoders and adders explained
A combinational circuit's output depends only on its current inputs, with no stored state. Multiplexers, decoders, encoders and adders are the blocks GATE keeps testing, and a single 4-to-1 MUX can implement any three-variable Boolean function using just one inverter.
Boolean algebra and K-map minimization: a worked GATE guide
K-map minimization becomes routine once you can read the groupings. Six Boolean identity pairs, DeMorgan's two theorems, the SOP and POS canonical forms, and a four-variable map traced loop by loop from seven minterms and three don't-cares down to F = B' + A'D.