1.2 Memory and Storage
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The need for primary storage
To hold data, programs and instructions that are currently in use.
Types of Primary Storage
RAM ROM
RAM
Random Access Memory
ROM
Read Only Memory
The difference between RAM and ROM
• ROM is read-only, RAM can be read from and written to. • RAM is volatile, ROM is non-volatile
Purpose of RAM
RAM is used to hold the operating system and any open documents and programs that are Running At the Moment.
Purpose of ROM
ROM stores instructions and data that are needed for the computer to run, such as BIOS program.
Virtual Memory
Virtual Memory is the use of secondary storage as additional primary memory.
The need for Virtual Memory
Allows data in RAM that isn’t currently being used to be transferred to the hard disk to free up space.
Cache
Cache is a type of high-speed RAM that is used to temporarily hold frequently used instructions.
The need for Secondary Storage
• Storage of programs and data when the power is turned off. • Semi-permanent storage of data that can change. • Backup of data files. • Archive of data files.
Types of Secondary Storage
• Optical • Magnetic • Solid State
Advantages of Optical
• Cheap • Portable
Disadvantages of Optical
• Slow write speed • Not durable • Low storage
Examples of Optical
CD, DVD, Blu-Ray
Advantages of Magnetic
• Cheap • Durable • High storage
Disadvantages of Magnetic
• Slow write speed • Not portable
Examples of Magnetic
Hard drive, tape drive, floppy disk.
Advantages of Solid State
• Portable • Durable • High storage • Fast write speed
Disadvantages of Solid State
• Expensive
Examples of Solid State
USB drive, SD card, Micro SC card.
Nibble
4 bits
Byte
8 bits
Kilobyte (KB)
1000 bytes