Memory and Storage Devices

Primary vs secondary memory, RAM vs ROM, and the units of digital storage from bit to yottabyte.

📖 ~4 min read 💻 RRB NTPC / Group D — Computer Awareness

Type	Feature
Primary Memory (RAM, ROM)	Directly accessible by CPU; RAM is volatile (data lost on power off)
Secondary Memory	Non-volatile, used for permanent storage — Hard Disk, SSD, Pen Drive, CD/DVD

RAM	ROM
Random Access Memory	Read Only Memory
Volatile (data lost when powered off)	Non-volatile (data retained without power)
Read/Write memory	Mostly Read-only; stores firmware/BIOS

Bit → Byte (8 bits) → Kilobyte (KB) → Megabyte (MB) → Gigabyte (GB) → Terabyte (TB) → Petabyte (PB) → Exabyte (EB) → Zettabyte (ZB) → Yottabyte (YB)

💡 1 Byte = 8 Bits | 1 KB = 1024 Bytes | 1 MB = 1024 KB | 1 GB = 1024 MB

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