Reading (computer)

Reading is an action performed by computers, to acquire data from a source and place it into their volatile memory for processing. Computers may read information from a variety of sources, such as magnetic storage, the Internet, or audio and video input ports. Reading is one of the core functions of a Turing machine. Reading is an action performed by computers, to acquire data from a source and place it into their volatile memory for processing. Computers may read information from a variety of sources, such as magnetic storage, the Internet, or audio and video input ports. Reading is one of the core functions of a Turing machine. A read cycle is the act of reading one unit of information (e.g. a byte). A read channel is an electrical circuit that transforms the physical magnetic flux changes into abstract bits. A read error occurs when the physical part of the process fails for some reason, such as dust or dirt entering the drive. For example, a computer may read information off a floppy disk and store it temporarily in random access memory before it is written to the hard drive to be processed at a future date. Complementary metal–oxide–semiconductor (CMOS) is a non-volatile medium. It is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. Memory is read through the use of a combination of p-type and n-type metal–oxide–semiconductor field-effect transistors (MOSFETs). In CMOS logic, a collection of n-type MOSFETs are arranged in a pull-down network between the output node and the lower-voltage power supply rail, named Vss, which often has ground potential. By asserting or de-asserting the inputs to the CMOS circuit, individual transistors along the pull-up and pull-down networks become conductive and resistive to electric current, and results in the desired path connecting from the output node to one of the voltage rails. Flash memory stores information in an array of memory cells made from floating-gate transistors. Flash memory utilizes either NOR logic or NAND logic. In NOR gate flash, each cell resembles a standard MOSFET, except the transistor has two gates instead of one. On top is the control gate (CG), as in other MOS transistors, but below this, there is a floating gate (FG) insulated all around by an oxide layer. The FG is interposed between the CG and the MOSFET channel, and because the FG is electrically isolated by its insulating layer, any electrons placed on it are trapped there and, under normal conditions, will not discharge for many years. When current flow through the MOSFET channel binary code is generated, reproducing the stored data. NAND gate flash utilizes tunnel injection for writing and tunnel release for erasing. NAND flash memory forms the core of the removable USB storage devices known as USB flash drives, as well as most memory card formats available today. The magnetic medium is found in magnetic tape, hard disk drives, floppy disks, and so on. This medium uses different patterns of magnetization in a magnetizable material to store data and is a form of non-volatile memory. Magnetic storage media can be classified as either sequential access memory or random access memory although in some cases the distinction is not perfectly clear. Small polarized ferrous cores in the shape of wires or poles are flipped along the surface of reading and writing into the desired data is stored. Accessing different parts of the medium involves winding the wire forward or backward until the point of interest is found. Data is read through a small reading peripheral which amplifies which side the ferrous cores are arranged.