Main functions of printers. Give description to MFP, MFD, AIO, virtual, dot-matrix, ink-jet, laser, thermal transfer, thermal printers and plotters

In computing, a printer is a peripheral which produces a hard copy or printout of documents stored in electronic form, usually on physical print media such as paper or transparencies.

In addition, a few modern printers can directly interface to electronic media such as memory sticks or memory cards, or to image capture devices such as digital cameras, scanners; some printers are

combined with scanners and/or fax machines in a single unit, and can function as photocopiers.

Printers that include non-printing features are sometimes called Multifunction Printers (MFP), Multi-Function Devices (MFD), or All-In-One (AIO) printers. Most MFPs include printing, scanning, and copying among their features. A Virtual printer is a piece of computer software whose user interface and API resemble that of a printer driver, but which is not connected with a physical computer printer. A dot-matrix printer uses a group, or matrix, of pins to create precise dots required to shape a character. A print head containing tiny pins strikes an inked ribbon to make letters and graphics. They print text and graphics and nowadays some of them can print up to 500 characters per second (cps). They are slower than laser printers but much cheaper.

An ink-jet (also called bubble-jet) printer generates an image by spraying tiny, precise drops of ink onto the paper.. This type of printer is quite fast, silent and not so expensive as a laser printer. A standard ink-jet has a three-colour cartridge, plus a black cartridge. A laser printer uses a laser beam to fix the ink to the paper. A laser works like a photocopier – it scans the image with a laser beam and transfers it to paper with a special ink powder called toner which is attracted to paper by an electrostatic charge and then fused on by a hot roller. Laser printers are fast and produce a high resolution of 1,200 to 2,400 dpi, so they are ideal for businesses and for professional graphics work. They are constantly being improved.

Thermal transfer printers use solid sticks of colored ink, which are melted and fed into a piezo crystal operated print-head which sprays the ink on a rotating, oil coated drum. The paper then passes over the print drum and the image is transferred, or transfixed, to the page. Drawbacks of the technology include high power consumption and long warm-up times from a cold state.

Thermal printers work by selectively heating regions of special heat-sensitive paper. They are silent and considered to be inexpensive.

A plotter is a vector graphics (using geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical equations, to represent images in computer graphics) printing device which uses ink and fine pens held in a carriage to draw detailed designs on paper. It's used in computer- aided design, maps, 3-D technical illustrations, construction plans, engineering drawings and other technical illustrations.

13. Computer data storage. What do terms memory, storage, primary storage, secondary storage refer to?

Computer data storage, often called storage or memory, refers to computer components, devices, and recording media that retain digital data used for computing for some interval of time. It provides one of the core functions of the modern computer, that of information retention.

Memory usually refers to a form of semiconductor storage known as random access memory (RAM) and sometimes other forms of fast but temporary storage. Storage more commonly refers to mass storage - optical discs, forms of magnetic storage like hard disks, and other types slower than RAM, but of a more permanent nature. Primary storage is the only one directly accessible to the CPU which continuously reads instructions stored there and executes them as required. Any data actively operated on is also stored there in uniform manner.

The specific functions of internal storage are to hold (store): all data to be processed; intermediate results of processing; final results of processing; all the instructions required for ongoing process. Another name for primary storage is memory, because of its similarity to a function of the human brain.

Secondary storage, or storage is not directly accessible by the CPU. The computer usually uses its input/output channels to access secondary storage and transfers the desired data using intermediate area in primary storage. Secondary storage does not lose the data when the device is powered down—it is non-volatile.

14. The most commonly used storage technologies: semiconductor, magnetic and optical. Their performance characteristics.

The most commonly used storage technologies are semiconductor, magnetic, and optical.

The most important performance characteristics of a storage unit are:

 Speed, measured in cycle time.

 Capacity, measured by the number of machine words or binary digits.

 Reliability, measured by the number of failures per unit of time.

Semiconductor memory uses semiconductor-based integrated circuits to store information. In modern computers, primary storage almost exclusively consists of dynamic volatile semiconductor memo ry or dynamic random access memory. Since the turn of the century, a type of non-volatile semiconductor memory known as flash memory has steadily gained share as off-line storage for home computers. Removable flash memory is solid-state, rewritable memory; it is non-volatile, so it retains data when the power is turned off. This explains its popularity in small devices.

Flash memory cards are found in cameras, PDAs and music players. Flash drives, also known as thumb or pen drives, are connected to a USB port of the computer. They let you save and transfer data easily. Magnetic storage uses different patterns of magnetization on a magnetically coated surface to store information. It is non-volatile. The information is accessed using one or more read/write heads which may contain one or more recording transducers. A disk drive spins the disk at high speed and reads its data or writes new data onto it. Magnetic storage takes these forms:

 Floppy disk,

 Hard disk,

 A portable hard drive is an external unit with the drive mechanism and the media all in one sealed case. You can use it to make a backup, a spare copy of your files, or to transport data between computers.

 Magnetic tape data storage, used for tertiary and off-line storage.

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