Chapter 2
Computer Hardware, CPU & Memory Hierarchy
Deep dive into CPU registers, RAM, ROM, Cache hierarchy, SSD vs HDD, and input/output peripherals.
Hardware Architecture & Memory Hierarchy
Computer memory is categorized into Primary (Internal) and Secondary (External) storage.
1. Primary Memory:
- RAM (Random Access Memory): Volatile memory where currently running applications and active OS files are kept. Loses contents on power loss. Includes SRAM (faster, expensive, used for Cache) and DRAM (dynamic, needs periodic refreshing).
- ROM (Read Only Memory): Non-volatile memory containing firmware instructions such as BIOS / UEFI needed to perform POST (Power-On Self-Test) and boot the machine. Types include PROM, EPROM, and EEPROM.
- Cache Memory: Extremely high-speed static RAM positioned between CPU registers and main RAM to store frequently accessed instructions. Organized into L1, L2, and L3 caches.
2. Secondary Memory:
- HDD (Hard Disk Drive): Magnetic storage with rotating platters and read/write heads. Large capacity at economical cost.
- SSD (Solid State Drive): Uses NAND flash memory chips. Delivers 5x to 30x faster read/write speeds, zero noise, and lower power consumption than traditional mechanical HDDs.
- Optical Discs: CD (700 MB), DVD (4.7 GB), Blu-ray (25 GB - 100 GB).
Hands-on Laboratory Procedures & Shortcuts
Follow the steps below to practice directly on your computer.
Hands-on Lab Exercise:
- Disk Management: Open
diskmgmt.mscin Windows to inspect disk partitions, file systems (NTFS / FAT32), and unallocated space. - Task Manager Memory Inspection: Press
Ctrl + Shift + Esc, switch to the Performance tab, and observe RAM utilization, Committed memory, and In-use Cache memory. - File Clean-up: Run
cleanmgr(Disk Cleanup) to delete temp files and free up secondary drive space.
Watch the video class above while following along with the practical exercises.
Key Summary & Revision Bullet Points
Quick cheat-sheet to review before online examinations.
• Volatile: RAM, Cache, Registers (Data vanishes on power down).
• Non-Volatile: ROM, Hard Disk, SSD, Pen Drive, SD Card.
• Speed Hierarchy: CPU Registers > L1 Cache > L2 Cache > L3 Cache > RAM > SSD > HDD > Optical Media.
• BIOS/UEFI: Performs POST and points to the bootable partition (MBR/GPT).
• Non-Volatile: ROM, Hard Disk, SSD, Pen Drive, SD Card.
• Speed Hierarchy: CPU Registers > L1 Cache > L2 Cache > L3 Cache > RAM > SSD > HDD > Optical Media.
• BIOS/UEFI: Performs POST and points to the bootable partition (MBR/GPT).
Frequently Asked Viva & Exam Questions
Review these standard questions frequently asked in diploma exams and job interviews.
Q1: Why is an SSD faster than an HDD?
Ans: An HDD relies on mechanical moving parts (spindle motor, magnetic platters, actuator arm) requiring seek time. An SSD uses solid-state flash memory without moving parts, enabling near-instant electronic data access.
Q2: What is Virtual Memory?
Ans: Virtual memory is a technique where the Operating System temporarily transfers pages of data from RAM onto secondary disk storage (pagefile.sys) when physical RAM is exhausted.
Ans: An HDD relies on mechanical moving parts (spindle motor, magnetic platters, actuator arm) requiring seek time. An SSD uses solid-state flash memory without moving parts, enabling near-instant electronic data access.
Q2: What is Virtual Memory?
Ans: Virtual memory is a technique where the Operating System temporarily transfers pages of data from RAM onto secondary disk storage (pagefile.sys) when physical RAM is exhausted.
Interactive Chapter Quiz
Test your mastery immediately! Click an option to see instant answer feedback.
Q1 Which of the following is volatile memory?
A. ROM
B. Hard Disk
C. RAM
D. Flash Drive
Explanation: RAM loses all its stored information as soon as electric power is switched off.
Q2 Which memory is placed directly between the CPU and main RAM for faster access?
A. Virtual Memory
B. Cache Memory
C. Secondary Storage
D. EEPROM
Explanation: Cache memory stores repeatedly needed instructions directly next to the processor.
Q3 What does BIOS stand for?
A. Basic Input Output System
B. Binary Input Output Service
C. Boot Integrated Operating Setup
D. Broadband Interface Online System
Explanation: BIOS stands for Basic Input Output System.
Q4 Which storage device has no moving mechanical parts?
A. Floppy Disk
B. Hard Disk Drive
C. Solid State Drive (SSD)
D. Magnetic Tape
Explanation: SSDs utilize flash memory chips without any moving motors or read heads.
Q5 How many Megabytes (MB) make 1 Gigabyte (GB)?
A. 1000 MB
B. 1024 MB
C. 512 MB
D. 2048 MB
Explanation: In binary measurement, 1 GB = 1024 MB.