Introduction
"IT General Knowledge" (IT GK) is the single most frequently examined slice of the ICT section in Bangladeshi government job tests — BCS (preliminary and written), Bank (Officer / IT Officer), and other IT-officer recruitment. Unlike deep programming, this part rewards broad, precise factual recall plus a few small calculations: computer fundamentals, generations, hardware and memory, software and languages, number systems, networking and the Internet, famous "firsts", abbreviations, and Bangladesh-specific ICT facts.
The good news: the syllabus is finite and stable. If you master the facts and the four or five calculative skills in this lesson (number-system conversion, memory-size arithmetic, data-transfer time, IP basics), you can answer almost any objective question that appears. This lesson builds every idea from first principles so the facts stick instead of being memorized blindly.
Learning objectives
After studying this lesson you should be able to:
- Define a computer and its core characteristics, and distinguish data vs information and hardware vs software.
- Name the five computer generations, their switching technology, and representative machines.
- Explain the CPU (ALU, CU, registers) and the memory hierarchy (register → cache → RAM → secondary storage).
- Convert numbers between binary, decimal, octal and hexadecimal, and compute memory sizes using powers of 2.
- Classify software and programming-language generations, and distinguish compiler / interpreter / assembler.
- Describe network types, topologies, the OSI & TCP/IP models, IP addressing, and common networking devices.
- Recall key Internet/Web facts, inventors, "firsts", important abbreviations, and Bangladesh ICT milestones.
- Answer number-based questions on data transfer time and storage capacity.