Supplement
Date: 2015-10-07; view: 435.
Optical input devices
| Device | Comments |
| Lightpen | It detects differences in reflected light. It can be used for drawing directly on the monitor screen or for reading printed optical characters or barcodes. |
| Graphical tablet | Used with a lightpen for drawing. The user draws on the tablet with a lightpen as if they were drawing on a sheet of paper. |
| Barcode reader | A special kind of lightpen for reading barcodes. Barcodes are used to identify items for stock control and pricing. |
| Scanner | Used to input text and graphics from a printed page. |
| Digital camera | Used to take pictures of an object. The picture is stored electronically and can be edited using a computer. |
| Voice input device | |
| Device | Comments |
| Microphone | Used to input sound |
In electronics, a multi-level cell (MLC) is a memory element capable of storing more than a single bit of information.
MLC NAND flash is a flash memory technology using multiple levels per cell to allow more bits to be stored as opposed to SLC NAND flash technologies, which uses a single level per cell. Currently, most MLC NAND stores four states per cell, so the four states yield two bits of information per cell. This reduces the amount of margin separating the states and results in the possibility of more errors. Multi-level cells which are designed for low error rates are sometimes called enterprise MLC (eMLC).
Flash memory stores data in individual memory cells, which are made of floating-gate transistors. Traditionally, one bit of data was stored in each cell in so-called single-level cells, or SLC flash memory. SLC memory has the advantage of faster write speeds, lower power consumption and higher cell endurance. However, because it stores less data per cell, it costs more per megabyte of storage to manufacture. Due to faster transfer speeds and longer life, SLC flash technology is used in high-performance memory cards.