Computer Interfaces and Peripherals - CSS407 PDF

CSS407 Computer Interfaces and Peripherals Introduction Prepared by: Prof. Dr. M. Elmahy and Dr. Rania Sherif  Course Metric: IMPACT FACTOR MEASUREMENT Attendance 5% Midterm...

CSS407 Computer Interfaces and Peripherals Introduction Prepared by: Prof. Dr. M. Elmahy and Dr. Rania Sherif  Course Metric: IMPACT FACTOR MEASUREMENT Attendance 5% Midterm 20 % Lab, Assignments and participation 5% Final Exam 70 % References o A+ Guide to Managing and Maintaining Your PC, 6th Edition by Jean Andrews. o A+ Guide to Managing and Troubleshooting PC’s, 4th Ed., 978-0-07-179591-3, Mike Meyers, McGraw Hill. o Computer Peripherals and Interfaces, 2nd edition, Amit Kamra and Pankaj Bhambri, 2008. o Computer Peripherals and Interfacing, Jyoti Snehi. Objectives of This Course Explain the function of a computer output device. List several types of output devices. Describe the purpose of a computer input device. Describe several input device variations. Explain the purpose of a computer storage device. List the important specifications for a computer hard drive. Describe the purpose of a “modem“. Explain how a “modem“ operates. Define the term “computer network“. Explain the function of a video interface. Peripherals ‫األجهزة الطرفية‬ o Devices that are separate from the basic computer: Not the CPU, memory, power supply. o Classified as input, output, and storage o Connect via: Ports: parallel, USB, serial. Interface to systems bus. Peripherals Peripherals o Computer peripherals work in different ways. o Linking a peripheral to the processor is a difficult task. o They: work at different speeds, use different codes, transfer different amounts of data at a time, and even work at different voltages.  Interface ‫الربط – الوسيط‬ o An interface is the hardware and software needed between a processor and a peripheral device in order to compensate ‫ يستعوض‬for differences ‫ االختالف‬in their operating characteristics ‫خصائص‬. o The interface allows the two devices to communicate correctly. Ports and Peripherals Ports are an interface between the computer and a peripheral device. Such as a disk drive, mouse, printer, modem, monitor, camera, FLASH drive or keyboard. Examples: Serial, Parallel USB, hot wires electronics set. Interface Functions o An interface will have to perform many of the functions (jobs) listed below: 1. Buffering and Spoolling. 2. Data format conversion. 3. Voltage conversion. 4. Protocol conversion. 5. Status signal handling. o This will vary depending on the characteristics of the device. 1- Buffers and Spoolers ‫التخزين المؤقت‬: o Buffers and Spoolers ‫التخزين المؤقت‬: Spooling is ideal for managing multiple task simultaneously and ensuring resources are utilized efficiently. Buffering helps in managing transfer of data between devices with different speeds. Spoolers Resources Buffers Data o Buffers and spoolers are terms generally associated with printers. The terms are not dedicated ‫ مكرسة‬to printers but that is the context ‫ السياق‬that will be described. Buffers What is a Buffer? ❖ Is an area of memory used for the transfer of data between a computer and a peripheral. ❖ Provides temporary storage of data. ❖ Using a buffer provides a link between a device and the processor and helps compensate for any differences in their working speeds.  Buffers Why use buffers? o Peripherals operate at much slower speeds than the CPU. Using buffers helps the computer system compensate for the differences in Speed operating speeds between CPU and its Protocols Voltage peripherals. Frequency o When transferring data out to a peripheral such as a printer, the processor can transfer it faster into the buffer and the buffer will send it to the printer at a speed that the printer can cope with. o The use of buffers reduces the frequency with which the CPU is interrupted to deal with input. Data from a keyboard is stored in a buffer until there is a larger amount of data for the CPU to process.  Spoolers o Spooling is another technique used in the transfer of data to a slow peripherals. o Spooling is a method of improving system performance. o This frees up ‫ يحرر‬the much faster CPU to process other tasks. In this case the data intended ‫ المعدة‬for the peripheral, is transferred to storage, often a hard disk. E.g.: printer Example: Then when the processor is inactive (sleeping mode) , it will transfer the data to the printer at an acceptable speed. This is also called background printing. Buffers vs Spoolers o Spooler vs Buffer A buffer is limited by the amount of RAM whereas a spooler uses backing storage which has a very large capacity. o Use BOTH for optimum efficiency.  2 - Data Format Conversion ❖ The processor and the peripheral device may format ‫تشكيل‬ data in different ways and So, the interface may have to convert the format of the data. ❖ Two common format conversions: a) Serial to parallel. b) Analogue to digital. a) Serial to Parallel Serial transmission is where data is sent along a single line one bit at a time. Parallel transmission is where data is sent several bits a time along multiple lines. The processor uses parallel transmission but many devices send and receive data serially so the data format must be converted.  Serial VS Parallel Comparing serial and parallel in terms of performance: Parallel is faster over short distances. When data is sent over longer distances in parallel the data can fall out of‫تسقط‬ alignment ‫االنتظام‬and so becomes corrupted ‫تتلف‬. This known as “skew” ‫منحرف – مائل‬. Serial transmission is more efficient when longer distances are involved.  Comparing serial and parallel in terms of performance Interface 0 0 1 1 0 1 0 1 0 1 0 0 Serial data format 1 1 0 0 1 1 Parallel data format b) Analogue to Digital The processor is a digital device and works with digital signals. Some devices send analogue signals and so these signals have to be converted into digital signals for processing. Examples of analogue signals include: Signals being received by a modem on a telephone line. Recording using a microphone. An interface performs the data format conversion. Conversion between analogue and digital forms Analogue signals: Many electrical signals are analogue signals. These signals vary between two limits. Analogue signals that are sent in from peripherals to the digital form that the CPU can handle. If you could see an analogue signal it would look roughly like this: Example of peripherals uses analog signal: Microphones Speakers and headphones Monitors (old CRT and analog monitors) Sensors (e.g., temperature, pressure, or light sensors) Conversion between analogue and digital forms Digital signals: Computers can only work with digital signals, which have only two values – on or off. A digital signal therefore consists of a series of “Ons” and “OFFs”. An On signal is represented by a 1 and an Off by a 0. 0 1 1 0 0 1 1 End 23