Direct Answer: In computer architecture, RAM (Random Access Memory) is high-speed, volatile primary memory that temporarily stores active operating system files, programs, and data while the computer is turned ON, losing all contents when power is turned off. In contrast, ROM (Read Only Memory) is permanent, non-volatile primary memory that stores critical firmware instructions like the BIOS (Basic Input/Output System) and bootstrap loader needed to boot the computer, retaining its data even after power is turned off.
Comprehensive Comparison Table: RAM vs ROM
| Parameter |
RAM (Random Access Memory) |
ROM (Read Only Memory) |
| Data Retention (Volatility) |
Volatile: Data is lost completely when power is switched off. |
Non-Volatile: Data is permanently retained even when power is turned off. |
| Operation / Access Mode |
Read and Write memory (data can be read, written, altered, and erased continuously). |
Read-only memory (data is written during manufacturing or flashed; normally cannot be altered during normal CPU operations). |
| Primary Purpose |
Stores active applications, running background tasks, and browser tabs for CPU processing. |
Stores bootstrap loader, BIOS/UEFI firmware, and hardware diagnostics routines required to start the PC. |
| Speed & Access Time |
Extremely fast (nanosecond access times: 10–50 ns). |
Slower than RAM (access times: 50–200 ns). |
| Typical Capacity |
High capacity: 4 GB, 8 GB, 16 GB, 32 GB, 64 GB. |
Small capacity: 4 MB, 8 MB, 16 MB. |
| Types / Subcategories |
• SRAM (Static RAM): Uses flip-flops, faster, no refresh required, used in CPU Cache (L1, L2, L3).
• DRAM (Dynamic RAM): Uses capacitor-transistor pairs, needs periodic refreshing, used in main memory (DDR4, DDR5).
|
• PROM: Programmable ROM (programmed once).
• EPROM: Erasable PROM (erased using Ultraviolet light).
• EEPROM: Electrically Erasable PROM (erased electrically, used in Flash memory & modern BIOS).
|
| Cost per Unit Bit |
Higher cost compared to secondary storage; SRAM is costlier than DRAM. |
Inexpensive per chip due to small capacity requirements. |
Summary for SSC CGL & Bank Exam Aspirants
Remember that both RAM and ROM are classified as Primary (Internal) Memory because they communicate directly with the CPU. Secondary memory (Hard Disks, SSDs, Pen Drives) is auxiliary non-volatile storage.
