Storage

Primary Storage

Storage that can be accessed directly by the CPU. Usually referred to as "memory"
Random Access Memory (RAM)
Read Only Memory (ROM)
byte a group of 8 bits
address a number assigned to the storage location
volatile data is lost when power goes
BIOS Basic Input/Output System - control computer when powered on, tests sys hardware and load OS

Note

The BIOS is stored in ROM, where RAM is "volatile" ROM is not!

When your computer runs out of physical RAM, it uses a trick called Virtual Memory (or Swap on Linux/macOS) to keep things running.

Expansion: It simulates additional RAM by using a portion of your hard drive or SSD as if it were memory.
The "Swap" Process: When RAM is full, the operating system moves inactive data into a Page File or Swap Partition on the disk.
Performance Hit: Accessing data from a drive is significantly slower than accessing it from RAM.
Stability: It prevents programs from crashing immediately when you hit your RAM limit, giving the system a "buffer" to manage heavy workloads.

Magnetic media, electromagnets in read-write heads read and write data on discs coasted with magnetic materials
Optical media, light from lasers read and write data on specifically prepared discs
Electrical or solid stat storage, data is stored electrically
Cloud storage, off-site storage accessed over the internet
Block Storage Best for Virtual Machine disks, high-performance databases, and transactional applications.
Object Storage Best for Static assets like photos/videos, backups, logs, and massive "data lakes" for AI training.

Any system involving two states is called a binary system

Random access memory (RAM) acts as a temporary store of program instructions and data.
RAM consists of billions of memory locations with unique addresses.
The addresses can be accessed in any order
RAM is volatile and can be written to.
Dynamic RAM (DRAM) is slower that static RAM (SRAM) but is far cheaper.
Read-only memory is used to store basic info and instructions that a computer need to start-up.
Read-only memory (ROM) is non-volatile but cannot be written to.
Magnetic media, electromagnets in read-write heads read and write data on discs coasted with magnetic materials
Optical media, light from lasers read and write data on specifically prepared discs
Electrical or solid stat storage, data is stored electrically
Cloud storage, off-site storage accessed over the internet
Block Storage Best for Virtual Machine disks, high-performance databases, and transactional applications.
Object Storage Best for Static assets like photos/videos, backups, logs, and massive "data lakes" for AI training.
Billions of transistors in the CPU carry out millions of calculations per second.
Transistors act as switches, either on or off
These two states are represented byt either 0 or 1
All programs and data consist of billions of 1s & 0s which are called bits
Bits are grouped into the units:
- Nibble (4 bits)
- byte (8 bits)
- kilobyte (1024 Bytes, 8192 Bits)
- megabyte (1024 kilobytes, 8388608 bits)
- And so on!

Note

Example of working out how many bits are in a megabyte is 1024 x 1024 x 8.