You can go through below books for your preparation
Section A Quantitative Aptitude & Reasoning R. S. Aggrawal Section B Data Communication & Networking CompTIA Network+ Study Guide (Todd Lammle) Data communication and networking (Forouzan) C Programming Let Us C (Yashavant Kanetkar) C++ OOP balguruswamy Operating Systems Operating System Principles (Silberschatz, Galvin, Gagne) Section C Computer Architecture Computer Organization & Architecture (William Stallings) Digital Electronics Digital Design (Morris Mano) Modern Digital Electronics (R. P. Jain) Microprocessors Microprocessor Architecture, Programming & Applications with 8085 (Ramesh Gaonkar) The Intel Microprocessor (Barry Brey
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