Memory and Storage
beginner22 min read
Primary memory versus secondary storage, the memory hierarchy from registers to disk, RAM and ROM and their variants, cache, volatility, and the main secondary-storage technologies - magnetic, optical and solid state.
What you will be able to do
- Distinguish primary memory from secondary storage on speed, cost, volatility and role.
- Place registers, cache, RAM and disk in a memory hierarchy.
- Describe RAM, ROM and their common variants.
- Name the main secondary-storage technologies and their trade-offs.
What is inside this lesson
- 1Primary memory and secondary storage
- 2The memory hierarchy
- 3RAM
- 4ROM
- 5Secondary-storage technologies
- 6Common confusions
- 7Quick revision
- 8Practice
Get Pro for full access. This is section 1 of 8; the rest of the lesson opens with Pro at onelystop.in/upgrade.
Primary memory and secondary storage
- Primary (main) memory is the memory the CPU can read from and write to directly. It is fast, relatively expensive per byte, limited in size, and mostly volatile - its contents are lost when power is removed. RAM is the main example.
- Secondary storage holds data and programs not currently in use, and keeps them when the power is off (non-volatile). It is slower, much cheaper per byte, and far larger. The CPU cannot run a program straight from secondary storage; it must first be loaded into primary memory.
A rough rule: as you move closer to the CPU, storage gets faster, smaller and costlier per byte.
The lesson itself is for members
Reading the 8 sections above is free. A free account opens the first 2 topics of every subject in full, along with flashcards and private notes.