1.3 Input, Output & Storage

Question 1

Input & Output Devices

Answer 1

• Input: Device used to put data and information into a computer (E.g keyboard, mouse)
• Output: Device used to send data and information out of a computer (E.g speaker, printer)

Question 2

Optical Storage

Answer 2

• Read from and written to using lasers
• Binary information represented by portions of disc, either reflect (flat lands, 1) or scatter (recessed pits, 0)
• CDs: store small quantities of info. Used for audio files, text & images. Very portable but easily damaged, limited capacity & relatively slow transfer speeds. (CD-RW, written to more than once & CD-ROM, written once)
• DVDs: higher storage capacity than CDs, suited to storing digital videos (E.g movies)
• Blu-Ray: 5x more storage than DVDs, used for storing high-res films.

Question 3

Magnetic Storage

Answer 3

• Devices which store information magnetically represent binary information using 2 states (polarised & unpolarised)
• These two states can represent 1 and 0, allowing any information to be represented in binary form.
• Hard Disk Drives: between 500GB-5TB. Rotates magnetic platters at high speeds under a read/write head on an actuating arm. Somewhat slow data transfer speeds, can be damaged by movement
• Magnetic Tape: Wound onto reels, long tape passed through readers, check the polarity of the tape and read off a binary value. Bulky way to store data
• Floppy Disks: Thin magnetic disk, incredibly portable, typical capacity of 1MB-200MB.

Question 4

Flash Storage

Answer 4

• Fast & compact. Uses silicon semiconductors forming the logic gates NAND & NOR to store electrical charge in either high or low
• Represent the binary values True & False, used to represent information
• Erased and reprogrammed electronically, non-volatile,
• SSDs = good replacement for HDDs, same functionality but improved performance
• More expensive per GB than alternatives

Question 5

RAM & ROM

Answer 5

• Primary storage, used by OS (E.g code instructions)
• RAM: Random access memory, fast main memory used to store data & programs computer is currently using
• High access speeds
• More expensive per gigabyte, 4-8 GB
• Volatile, loses information when power is lost. Used as temporary storage while the computer is running.
• ROM: Read only memory, cannot be modified. Once programmed
• Used for storing fixed sequences of instructions (E.g bootstrap/startup routine)
• Non-volatile, retains its data even when the computer is powered off.

Question 6

Virtual Storage

Answer 6

• Storing information remotely so that it can be accessed
  by any computer w/ access
• Cloud storage (E.g Google Drive, Microsoft OneDrive) & Networked storage (E.g offices, schools)
• Stored on 100s of hard drives/SSDs formatted to act as a single piece of storage.
• Limitations: Network speed, high costs.