Computer Structure & Architecture 7d - Input, Output & Backing Storage

Computer Structure & Architecture7d - Input, Output & Backing Storage

Lesson 1 – Input and Output Devices

LI: Identify and describe the purpose of a range of computer input and output devices

• An input device is used to send information to the computer

• Computers can capture a range of inputs including key strokes, sound, graphics and video

• Input devices include, mice / touchpads, keyboards, microphones etc.

Input Devices - Resolution• Resolution is used to measure the quality of an image.• It is measured in DPI (dots per inch) • The more dots per inch an image has, the higher the quality of the image.• Resolution has an effect on file size – the higher the resolution, the larger

the file size.• Resolution is used to measure the quality of webcams and scanners.

Output Devices• An output device allows data to be displayed or passed out of a

computer.

• Data can be output in many ways including visually, aurally or on paper.

• Most computer and laptop monitors have an LCD screen (Liquid Crystal Display).

• TFT (Thin Film Transistor) is a type of LCD technology.

• Resolution is used to measure the quality of a monitor.

Output Devices• Printers are measured by how fast they can print (pages per minute)

and resolution.

• The output of a printer is known as a hardcopy, electronic copies are known as softcopies.

• Inkjet and laser printers can both print high resolution images.

• Laser printers are much faster than inkjet printers.

• A plotter is an output device which draws pictures using coloured pens.

Lesson 2 - Backing Storage & Interfaces

• Hard discs are found inside the computer base, but portable drives are available. Typical storage 20 GB to 2 TB

• Magnetic tape is still used today, mostly for backups, because it is cheap and reliable.

• Optical storage includes CD-R’s (700 MB), DVD-R’s (4.7 GB) and Blu-Ray discs (25 GB).

LI: Identify and describe the purpose of a range of backing storage devices and be able to identify the most suitable one for different tasks. Identify and describe the purpose of an interface.

Backing Storage• USB Flash Memory and Flash Cards (such as SD cards) are known as

solid state devices.

• Solid state devices are robust because they have no moving parts

• Sequential access only allows the data to be read into the computer in the same order in which it was saved (i.e. in a sequence). Magnetic tape is an example of sequential access.

• Random or direct access allows the user to access data or files on any order. Examples of random or direct access include USB flash drives, hard discs, CD-R’s, DVD-R’s and Blu-Ray discs.

Interfaces• Interfaces go between the computer and a device so they can work

together. This compensates for the differences between how they operate.

• Interfaces can be both hardware and software. Hardware interfaces include USB, VGA and HDMI ports. Software interfaces include driver software e.g. a printer driver.

• Interfaces deal with Data conversion (e.g. analogue to digital)SpeedData storage