Transcript Unit2x
C_ITCO011/C_ITCO111 LECTURER: E.DONDO Unit 2: System Components Data is transmitted by a computer via electrical signals which are stored in components called ‘transistors’. The electrical pathways that carry these signals are referred to as ‘buses’. Signaling methods can either be: ◦ differential or single-ended ◦ serial or parallel ◦ digital or analogue parallel data transfer refers to the type of data transfer in which a group of bits are transferred simultaneously . serial data transfer refers to the type of data transfer in which a group of data bits are transferred one bit at a time. so generally, the amount of data transferred serially is less that the data transferred in parallel per second. serial data transfer requires less pins/cables so the data can be transmitted over longer distances & smaller hardware can be used. Single-ended signaling ◦ is the simplest and most commonly used method of transmitting electrical signals over wires. ◦ One wire carries a varying voltage that represents the signal, while the other wire is connected to a reference voltage, usually ground. ◦ advantage of single-ended over differential signaling is that fewer wires are needed to transmit multiple signals Differential signaling ◦ method of transmitting information electrically with two complementary signals sent on two paired wires, called a differential pair. ◦ this technique improves resistance to electromagnetic noise compared with use of only one wire and an un-paired reference (ground). ◦ can be used for both analog signaling and digital signaling -analog is a continuous electrical signal -information is translated into electric pulses of varying amplitude. - best suited for audio and video transmission. -digital is a non-continuous electrical signal. -translation of information is into binary format (0 or 1) where each bit is representative of two distinct amplitudes. - best suited for computing and digital electronics. computers work with binary data.(base 2) the basic unit of data storage is a bit 1 bit = 0 or 1 8 bits = 1 byte 1024 bytes = 1 KB 1024 KB = 1 MB 1024 MB = 1 GB 1024 GB = 1 TB Binary values can be converted to: ◦ decimal (base 10) ◦ hexadecimal (base 16) External ports - I/O ports allow for additional devices to be connected to a PC. ◦ PC99 connectors PC99 is standard which defines colour codes for external ports e.g. PS/2 mouse (green) ,PS/2 keyboard (purple) ◦ Legacy port types Ports can be male, which have pin connectors, or female, which have hole connectors. PC99 Colour codes Male and female connectors PS/2 ports ◦ PS/2 is a serial bus. ◦ used to connect a keyboard and mouse. Serial ports ◦ aka RS-232 port or a communication ‘COM’ port. ◦ connects to modems, printers . Parallel ports ◦ also known as the ‘printer’ or ‘Centronics’ port. ◦ data is transferred simultaneously over eight wires . VGA(Video graphics array) ports ◦ is the standard analogue video interface for PC devices. ◦ interface carries red, green and blue (RGB) component video signals. SCSI IEEE 1394 (Firewire) ◦ uses a parallel data stream with hardware handshaking(uses handshake signals between devices ) and control signals(parity error-checking). ◦ supports a variety of devices e.g. dot-matrix printers to scanners, plotters ◦ is a serial bus interface standard for high-speed communications and isochronous real-time data transfer. ◦ FireWire devices are Plug and Play- the OS auto-detects a new device and asks for the driver disk. Hot-pluggable - they can be connected and disconnected at any time, even with the power on. HDMI and other display ports ◦ only carries a digital signal; it does not support analogue signals. ◦ supports both video and audio digital streams as well as remote control and digital content protection. ◦ Other display ports Composite video S-video Component (RGB) video USB(Universal serial bus) ports ◦ USB was designed to standardize the connection of computer peripherals (e.g. keyboards, disk drives) to PCs. ◦ Used to communicate and also to supply electric power. ◦ USB supports hot swapping i.e. it can detect and configure a hot swappable device without requiring a restart. Input devices ◦ peripherals that enable a user to enter data and select commands. Mouse Digital cameras Scanners Biometric devices Joysticks/game pads Bar code readers Touch sensitive screens Output devices ◦ peripheral devices that are capable of presenting information from a computer. Monitors produce soft copies of the output. Printers produce hard copies of the output. Can be impact printers(e.g. dot matrix) or non-impact printers(e.g. laser) 1.Explain ◦ parallel and serial communication. ◦ analog and digital transmission. 2. Briefly discuss the various types of mouse(s).