CMOS is RAM. It is traditionally called CMOS RAM because it uses a volatile, low-power complementary metal–oxide–semiconductor (CMOS) SRAM powered by a small battery when system and standby power is off. This allows it to retain data even when the main power is off.
Understanding CMOS RAM
CMOS RAM is a type of memory that uses CMOS technology. This technology is known for its low power consumption, making it suitable for storing data that needs to be retained for extended periods.
Key Characteristics of CMOS RAM
- Volatile Memory: CMOS RAM is volatile, meaning it loses its data when power is removed.
- Low Power Consumption: CMOS technology allows for very low power consumption.
- Battery Backup: Typically, CMOS RAM is backed up by a small battery to maintain data when the main power is off. For example, the Motorola MC146818 or similar.
- SRAM Based: It uses static RAM (SRAM) cells, which are faster and require less power than dynamic RAM (DRAM) but are also more expensive.
CMOS RAM vs. ROM
| Feature | CMOS RAM | ROM |
|---|---|---|
| Memory Type | Random Access Memory (RAM) | Read-Only Memory (ROM) |
| Volatility | Volatile (requires power) | Non-volatile (retains data) |
| Data Storage | Temporary data | Permanent/Semi-permanent data |
| Data Modification | Can be read from and written to | Primarily read from |
Common Uses of CMOS RAM
CMOS RAM is commonly used to store the BIOS settings, system time, and other configuration data in computers.
