Higher Computing Computer Systems S. McCrossan 1 Higher Grade Computing Studies 4. Peripherals Input Devices Keyboard Mouse Scanners Microphone Digital Camera Digital Video Camera

Higher Computing Computer Systems S. McCrossan 2 Higher Grade Computing Studies 4. Peripherals Input Devices - Scanners A scanner can be used to digitise (turn analogue data into a digital image) images/photographs. The resultant digital representation of the scanned image is a bitmap.

Higher Computing Computer Systems S. McCrossan 3 Higher Grade Computing Studies 4. Peripherals Input Devices - Scanners Hardware features of scanners: Resolution - the number of pixels/dots per inch (dpi). The greater the dpi the better the quality of the image produced. Bit depth - the number of bits used to represent the colours of a pixel. The more colours available then the fine differences between the colours can be shown. Interface – how its connected to the PC, i.e. USB. Accuracy – the resolution and bit depth capacity of the scanner will determine how close the computer image is to the original.

Higher Computing Computer Systems S. McCrossan 4 Higher Grade Computing Studies 4. Peripherals Input Devices - Scanners Advantages cheaper than a digital camera. can scan existing photographs. can be used for other purposes.

Higher Computing Computer Systems S. McCrossan 5 Higher Grade Computing Studies 4. Peripherals Input Devices – Microphone/Sound Sound is an analogue waveform. So it needs to be converted to digital signal for it to be stored in a computer.

Higher Computing Computer Systems S. McCrossan 6 Higher Grade Computing Studies 4. Peripherals Input Devices – Microphone/Sound The sound signal is captured and re- created by sampling. The sampling rate determines how many samples are taken of the analogue signal every second. The sample measurement is stored using a number of bits, called the sampling resolution. Sample taken from signal. Accuracy - the higher the sampling rate and the higher the sampling resolution, the more accurately the sound signal is re- created.

Higher Computing Computer Systems S. McCrossan 7 Higher Grade Computing Studies 4. Peripherals Input Devices – Microphone/Sound Music recorded digitally onto a CD is sampled 44,100 times per second (sampling rate) using 16 bits (sampling resolution). Capacity : a 2 minute sample from a CD will require * 16 * 120 = Mb. To reduce file sizes, we can use compression.

Higher Computing Computer Systems S. McCrossan 8 Higher Grade Computing Studies 4. Peripherals Input Devices – Digital Camera A digital camera obtains an image which is converted into digital data and stored in a flash card. Accuracy - this will depend on the array of photosensitive sensors. The more sensors and the smaller they are, the higher the resolution giving better detail and sharper edges. Capacity - this is based on the resolution and the number of images that can be stored. The higher the resolution the fewer images that can be stored.

Higher Computing Computer Systems S. McCrossan 9 Higher Grade Computing Studies 4. Peripherals Input Devices – Digital Camera A digital camera captures images which are 1600 * 1280 pixels in size and use colours. Calculate the storage requirements for an image from this camera. Number of pixels = 1600 x 1280 = colours are represented using 16 bits or 2 bytes Storage = x 2 bytes = 3.9 Mb

Higher Computing Computer Systems S. McCrossan 10 Higher Grade Computing Studies 4. Peripherals Input Devices – Digital Video Camera A video capture board is needed to generate digital video. A video using a screen size of 640 * 480 pixels and 24 bit- depth will require 23Mb per second. So the video capture board must be able to compress the video as it is being captured. Accuracy - this will depend on the quality of the source as well as the resolution settings on the board. Capacity - most memory cards can hold 1Gb or more.

Higher Computing Computer Systems S. McCrossan 11 Higher Grade Computing Studies 4. Peripherals Storage Devices Floppy disk Hard drive Magnetic tape CD-ROM, CD-R, CD-RW DVD-R, DVD-RW, DVD+R, DVD+RW and DVD-RAM You should be able to describe all of the above in terms of their capacity, speed and cost.

Higher Computing Computer Systems S. McCrossan 12 Higher Grade Computing Studies 4. Peripherals Storage Devices – Solid State Devices USB Flash Memory - A USB flash memory is a memory chip with a USB plug. It uses EPROM technology. Memory Card Reader/Writer - The card is placed in the USB memory card reader/writer, which is then recognized by the system as an external drive. The files can be transferred to and from the card.

Higher Computing Computer Systems S. McCrossan 13 Higher Grade Computing Studies 4. Peripherals Storage Devices – Solid State Devices There are two types: flash ROM and flash RAM. Flash RAM needs power to retain its data and flash ROM does not. Flash ROM is used in flash cards (for storing digital camera photographs) and memory sticks (or MP3 players).

Higher Computing Computer Systems S. McCrossan 14 Higher Grade Computing Studies 4. Peripherals Production of a Multimedia Catalogue You would need a high specification computer with the following … A fast processor to run applications quickly and view video and hear sound/music at an appropriate speed. A large amount of RAM to open media elements - video, sound etc, and run software. A large hard disk to store media elements - video, sound etc, while creating the catalogue. A DVD writer to store finished catalogue for transport to customers/clients.

Higher Computing Computer Systems S. McCrossan 15 Higher Grade Computing Studies 4. Peripherals Production of a Multimedia Catalogue A firewire/USB 2.0 interface to attach a camera to download pictures and video. A video card to capture pictures and video. A sound card to record sound/music. A high resolution monitor to view media elements. A digital video camera to record video frames. A microphone to record sound. A scanner to capture images from photographs, etc. A high resolution colour laser printer to print out the catalogue. Speakers to play back audio.

Higher Computing Computer Systems S. McCrossan 16 Higher Grade Computing Studies 4. Peripherals Setting up a LAN You would need a high specification computer with the following … A fast processor to run applications at an appropriate speed. A large amount of RAM to open media elements - video, sound etc, and run software. A large hard disk to store client software. A Network Interface Card to connect to the network. A monitor to view data or software. Cables to allow the computer to connect to the network.

Higher Computing Computer Systems S. McCrossan 17 Higher Grade Computing Studies 4. Peripherals Setting up a LAN A network laser printer to print documents across the network. A network server to store user files across the network. Switches to filter and forward packets on the network. Hubs to connect devices to the network.

Higher Computing Computer Systems S. McCrossan 18 Higher Grade Computing Studies 4. Peripherals Developing a School Website You would need a high specification computer with the following … A fast processor to run applications at an appropriate speed. A large amount of RAM to open media elements - video, sound etc, and run software. A large hard disk to store software. A Network Interface Card to connect to the network. A video card to capture pictures and video. A sound card to record sound/music. A high resolution monitor to view data/media elements.

Higher Computing Computer Systems S. McCrossan 19 Higher Grade Computing Studies 4. Peripherals Developing a School Website Cables to allow the computer to connect to the network. Digital Video Camera to take digital photographs and video. Scanner to capture images from photographs, etc. Inkjet printer to print out completed pages for checking.

Higher Computing Computer Systems S. McCrossan 20 Higher Grade Computing Studies 4. Peripherals Buffers A buffer is an area of computer memory that is allocated to transferring data between the computer and a peripheral. A buffer will be used when a fast acting part of the system is exchanging data with a slow acting device e.g. a printer. Most interfaces have buffers to store blocks of data while in transfer between the processor and the peripheral. This ensures that the processor is not held up by slow communications to and from the peripherals. The buffer must also keep the status of the peripheral so that the processor knows when it is able to send or receive data.

Higher Computing Computer Systems S. McCrossan 21 Higher Grade Computing Studies 4. Peripherals Spooling Another approach to ensuring the processor is not held up by slow peripherals is to send data to be spooled. This means that the data is sent to fast backing storage usually a hard disc. The data is then sent from the backing store to the peripheral in the gaps between processing actions (an example of this is background printing). The user can continue operating the computer while the data is being sent to the peripheral.

Higher Computing Computer Systems S. McCrossan 22 Higher Grade Computing Studies 4. Peripherals Interfacing Peripheral devices, such as printers, scanners, magnetic tape drives and hard disk drives, connect to processor. Each device works at different speeds, use different codes, transfer different amounts of data at a time and even work at different voltages. In order for these devices to communicate with the CPU they need to be interfaced. An interface is a unit that sits between the CPU and a peripheral device to ensure compatibility.

Higher Computing Computer Systems S. McCrossan 23 Higher Grade Computing Studies 4. Peripherals Interfacing – Data Conversion Data to be communicated has to be converted in such a way to be understood by the hardware or software doing the sending or receiving. Some data is sent by parallel data transmission, some by serial data transmission.

Higher Computing Computer Systems S. McCrossan 24 Higher Grade Computing Studies 4. Peripherals Interfacing – Data Conversion Parallel data transmission - Each bit of an 8-bit byte is sent at the same time along a set of parallel wires. The intention being that all bits of the byte arrive at their destination at the same time. TransmitReceive

Higher Computing Computer Systems S. McCrossan 25 Higher Grade Computing Studies 4. Peripherals Interfacing – Data Conversion Parallel data transmission Advantages Faster than sending out a single bit at a time Good for transmission over short distances Disadvantages Skewing can occur, due to interference, where the individual bits may arrive at their destination at different times.

Higher Computing Computer Systems S. McCrossan 26 Higher Grade Computing Studies 4. Peripherals Interfacing – Data Conversion Serial data transmission - each bit of an 8-bit byte is sent one at a time, over the communications line. TransmitReceive Start Bit 7 Data Bits Parity Bit Stop Bits

Higher Computing Computer Systems S. McCrossan 27 Higher Grade Computing Studies 4. Peripherals Interfacing – Data Conversion Serial data transmission Advantages Only one data channel required Good for transmission over long distances Disadvantages Slower than parallel transmission. Start and stop bits required to identify different pieces of data.

Higher Computing Computer Systems S. McCrossan 28 Higher Grade Computing Studies 4. Peripherals Interfacing Data Conversion - Data to be communicated has to be converted from the format understood by the processor to the format understood by the peripheral and vice versa, e.g. serial to parallel, analogue to digital. Voltage Conversion - As devices operate and send signals at differing voltages then these quantities must be converted to allow successful communication, e.g. one device may use 5v for a 1, while another device may use 7v for a 1.

Higher Computing Computer Systems S. McCrossan 29 Higher Grade Computing Studies 4. Peripherals Interfacing Data Storage - Data is stored in buffers inside the interface as it is transferred from the processor to the peripheral and vice versa. Protocol Signals - The conversion of different protocols to and/or from the processor and the peripherals. Status Signals - Supplies status signals to the processor indicating the readiness of the peripheral device to transmit or receive data.

Higher Computing Computer Systems S. McCrossan 30 Higher Grade Computing Studies 4. Peripherals Wireless Communication Some peripherals now have the ability to communicate with the CPU without physical connection (i.e. cabling). Bluetooth is an example of wireless technology. It is a short range radio technology aimed at simplifying communications among Internet devices and between devices and the Internet. It also aims to simplify data synchronisation between Internet devices and other computers.