Computer Structure
By Shannon MacLeod
Backing Storage
- People often get confused between main memory and backing storage, they are not the same.
- Main memory is located inside the computer system. It can either be RAM or ROM.
- Backing storage is outside the main processor, e.g. Hard Drives, CD/DVD drives, USB Flash Memory (Pen Drives).
Pen Drive
A USB flash drive is a data storage device that includes flash memory with an integrated Universal Serial bus (USB) interface.
Hard Drive
A hard disk drive (HDD) is a data storage device used for storing and retrieving digital information using rapidly rotating disks (platters) coated with magnetic material.
CD/DVD Drive
An optical disc drive (ODD) is a disk drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical discs.
ROM (Read Only Memory)
ROM
- ROM is used to store a small part of the operating system called the bootstrap loader.
- Data is stored permanently in ROM.
- Data is not lost when the power goes off.
- Data in ROM cannot be changed.
RAM (Random Access Memory)
- This is where the operating system is stored; it also holds all programs and data. You can purchase additional RAM chips and install them in your desktop computer, which normally speeds up multi-tasking.
- The processor can write to and read from RAM at high speed.
- Data held in RAM can be changed.
- All data in RAM is lost when the power is switched off.
Embedded Systems
- Small scale computers, with their own processors and memory.
- Built into machines to carry out a job.
- Can be found in many products such as:
- Digital cameras
- Mobile phones
- Cars
- Washing Machines