Nat 4/5 Computing Science Input, Output and Backing Storage Computer Systems Nat 4/5 Computing Science Input, Output and Backing Storage

Lesson Aims By the end of this lesson: Pupils will be able to: Describe the features, functions and uses of: keyboard, mouse, microphone, touchpad, digital camera, scanner, webcam Describe the features, functions and uses of monitor, LCD panel, inkjet and laser printers, loudspeakers Compare devices using appropriate characteristics including resolution, capacity, speed of data transfer, cost

Nat 4/5 Input Devices An input device is a device which creates some new information to put INTO the system

Nat 4/5 Output Devices An output device is a device which gets information FROM the system

Nat 4/5 Input/output Devices You have to be able to compare these devices in terms of appropriate characteristics such as: Resolution Capacity Speed of data transfer Cost

Backing Storage

a group of 8 bits – Single Letter Nat 4/5 Storage Terms Term Abbreviation Description Bit binary digit, 0 or 1 BIGGER -> Byte a group of 8 bits – Single Letter Kilobyte Kb 1024 bytes Megabyte Mb 1024 Kilobytes Gigabyte Gb 1024 Megabytes Terabyte Tb 1024 Gigabytes

Types Of Access Sequential Access Direct/Random Access Nat 4/5 Types Of Access Sequential Access Direct/Random Access To go from file A to file Z in a sequential-access system, you must pass through all files in order. Sequential access is sometimes called serial access Refers to the ability to access data at random. In a random-access system, you can jump directly to file Z. Disks are random access media, whereas tapes are sequential access media

Nat 4/5 Backing Storage Backing storage is used to save permanent copies of your files onto. There are 3 main types Magnetic These use magnetic fields to store the data Floppy Disks/Hard Disk Drives Magnetic Tapes Optical These store data by means of lasers ‘burning’ a disk CDROM/DVD/Blue Ray Solid State This uses no moving parts at all, uses memory chips USB Drives SSD Hard Drives

Nat 4/5 Floppy Disks Floppy Discs are small pieces of plastic film wrapped in a plastic case, they are fast becoming very scarce due to their slow transfer speed and limited capacity, have basically been replaced with USB Flash Drives Type Of Access Direct/Random Capacity 1.44 Megabytes Portability Very – Only requires another drive Transfer Rate Very Slow – 500Kbps Price Approx 25p per Disk

Hard Disk Drives (HDD’s) Nat 4/5 Hard Disk Drives (HDD’s) Hard Disk Drives are usually stored inside the computer. They use disks of metal which are magnetically charged. These are read by a small head – like a record player, which moves over the disks. Type Of Access Direct/Random Capacity Up to 3TB Portability Not portable Transfer Rate Up to 600Mbps Price Approx £40 - £220

Magnetic Tape Magnetic tapes are essentially the same as music tapes. Nat 4/5 Magnetic Tape Magnetic tapes are essentially the same as music tapes. To access a file you have to sequentially go through every file by fast forwarding or rewinding. They are however relatively cheap and easy to store. Often used for backups Type Of Access Sequential Capacity Up to 80GB Portability Very portable, requires another drive Transfer Rate Up to 7Mbps Price Up to £20 per tape

Optical Storage – CD/DVD Nat 4/5 Optical Storage – CD/DVD CD and DVD’s are optical media – a laser is used to burn holes (pits) into the surface of the disk. CD/DVD-R are recordable once CD/DVD-RW are rewritable more than once Type Of Access Direct/Random Capacity CD: 700MB (80 minutes audio) DVD 4.7GB up to 50GB Blue Ray Portability Very portable, requires another drive Transfer Rate Approx 130Mbps Price CDR: 20-30p DVDR: 30p-£1

Nat 4/5 USB Flash Drives USB (Universal Serial Bus) flash drives use memory chips to store data, this means there are no moving parts at all – this is called solid state storage, this means they are very robust. These are often used in MP3 – Players – Ipod Nano/Shuffle uses this. Some are even waterproof or branded with company logos Type Of Access Direct/Random Capacity Up to 128GB Portability Very portable, only requires USB port Transfer Rate 10-30MBps Price £10-£100+

Summary There are three main types of backing storage Optical Magnetic Solid State There are two main types of access Sequential Direct/Random Input Devices put information INTO the computer Output Devices get information FROM the computer