Comparing different types of Memory / Storage
It is important you understand the diffence between the various types of computer Memory and Storage. This table provides a summary of the key features:
Size (storage capacity) | Speed | Portable | Volatile (forgets without power) | Writable (can have new data saved) | Basic Use | |
Registers | upto 64 bits | Extremely Fast | N/A | Yes | Yes | Holds data during fetch - decode - execute cycle |
CACHE | L1 - 64KB L2 - upto 8MB | Very Fast | N/A | Yes | Yes | Holds regularly accessed data |
RAM | upto 32GB (typical) can go to 256 GB | Fast | N/A | Yes | Yes | Main memory (holds all active programs and data) |
ROM | upto 8MB | N/A | No | No | Contains boot data (Bios) | |
Magnetic Hard Drive | Typical 2 - 4TB | Slow | Partial (external drives) | No | Yes | Permanent Storage |
Solid State Drive | Typical 250GB - 1TB | Medium /Slow | Yes | No | Yes | Permanent Storage |
Flash Memory (Cards / Sticks) | Typical 32GB | Medium / Slow | Yes (very) | No | Yes | Permanent Storage / Data transfer |
DVD | Upto 17GB | Slow | Yes | No | Yes (if R/W) | Permanent Storage /Archive / Transfer |
CD | Upto 700MB | Slow | Yes | No | Yes (if R/W) | Permanent Storage /Archive / Transfer |