Used to represent the data size. A bit is the smallest unit size. The data is stored in binary value of 0 or 1. Computer memory is stored into smaller parts called as cells which has unique address in between 0 and it's size - 1.
||0 or 1
Types of memory
Based on location, it is of 4 types.
- Register memory
- Cache memory
- Primary memory
- RAM - Volatile
- DRAM - dynamic
- SRAM - static
- ROM - Nonvolatile
- Secondary memory
- Fixed storage
- HDD - Hard Disk Drive
- SSD - Solid State Disk
- Internal flash memory
- Removable storage
- Optical disks
- Memory cards
- Floppy disks
- Magnetic tapes
1. Register memory
- Smallest and fastest memory in computer.
- It is in the form of registers reside inside CPU.
- Temporarily stores the data for faster access by CPU.
2. Cache memory
- Small and faster than primary memory.
- It stores the frequently used data or instructions by CPU.
3. Primary memory
- It is the part of the computer unlike secondary memory.
3.A. RAM (Random Access Memory)
- It is volatile memory means that it stores data or instructions temporarily.
- It loses all data when we shut down the computer.
- It system's RAM is more, it works faster.
3.A.I. DRAM (Dynamic RAM)
- It refreshes it's memory constantly.
3.A.II. SRAM (Static RAM)
- It doesn't need to refresh so much constantly unlike DRAM.
- As it acts like system cache it works faster than DRAM.
3.B. ROM (Read Only Memory)
- It is nonvolatile memory means that it stores data or instructions permanently.
- It doesn't loose data when we shut down and helps in getting instructions for booting process.
3.B.I. PROM (Programmable ROM)
- Once program is written in PROM, it remains there forever.
3.B.II. EPROM (Erasable Programmable ROM)
- Until the memory is exposed to ultraviolet light, the content will be there forever.
3.B.III. EEPROM (Electrically Erasable Programmable ROM)
- Until the memory is exposed to electric charge, the content will be there forever.
4. Secondary memory
- It is connected to the computer externally to add additional functionality.