Card reader

A memory card reader is a device used for communication with a smart card or a flash memory card. A business card reader is a scanning device used to scan and electronically save business cards. A magnetic card reader is a device used to scan cards containing magnetic data strips. A punched card reader is a device used to read holes in punched cardboard cards.

Smart card readers

A smart card reader is an electronic device that reads smart cards. Some keyboards have a built-in card reader. There are external devices and internal drive bay card reader devices for PC. Some laptops have built-in smart card reader.

Some have a flash upgradeable firmware. The card reader supplies the integrated circuit on the smart card with electricity. Communication is done via protocols and you can read and write to a fixed address on the card.

Communication protocols

Name	Description
T=0	Asynchronous half-duplex byte-level transmission protocol.
T=1	Asynchronous half-duplex block-level transmission protocol.
T=2	Reserved for future full-duplex operations.
T=3	Reserved for future full-duplex operations.
T=CL	APDU transmission via contactless interface ISO 14443.

If the card is not using any standard transmission protocol, but uses a custom/proprietary protocol it has the communication protocol designation T=14.

With latest PC/SC CCID specifications the PC/SC Workgroup (www.pcscworkgroup.com) has defined a new way of smart card framework. It works with USB devices with the specific device class 0x0B. Readers with this class doesn't need device drivers because the operating system manufacturer supplies it by default.

PKCS#11 is an API, designed to be platform independent, defining a generic interface to cryptographic tokens, such as smart cards.

Memory card readers

A memory card reader is a device, typically having a USB interface, for accessing the data on a memory card such as a CompactFlash (CF), Secure Digital (SD) or MultiMediaCard (MMC). Most card readers also offer write capability, and together with the card, this can function as a pen drive.

Some printers and personal computers have a built-in card reader.

Today card readers can be categorized into three by the type and quantity of the card slots: single card reader (e.g. 1x SD-only), multi card reader (e.g. 9-in-1) and series card reader (e.g. 4x SD only). However, there are some kinds of memory cards with USB functions that do not need the card reader, such as the Intelligent Stick memory card, which can plug directly into a USB slot.

A multi card reader is a device used for communication with more than one type of flash memory card. Multi card readers do not have any built-in memory capacity, but are able to accept multiple types and styles of memory cards. Multi card readers typically use a USB interface to connect with a USB-capable computer or other device, enabling users to access information stored in the memory card. The number of compatible memory cards varies from reader to reader and can include more than 20 different types. The number of different memory cards that a multi card reader can accept is expressed as x-in-1, with x being the number of memory cards accepted. Such as 35-in-1. There are three categories of card readers sorted by the type and quantity of the card slots: single card reader (e.g. 1x SD-only), multi card reader (e.g. 9-in-1) and series card reader (e.g. 4x SD only).

The USB device class used is 0x08.

Access control card reader

Access control card readers are used in physical security systems to read a credential that allows access through access control points, typically a locked door. An access control reader can be a magnetic stripe reader, a bar code reader, a proximity reader, a smart card reader, or a biometric reader.

Light pen

A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a the computer's CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy. A light pen can work with any CRT-based display, but not with LCD screens, projectors and other display devices.

A light pen is fairly simple to implement. The light pen works by sensing the sudden small change in brightness of a point on the screen when the electron gun refreshes that spot. By noting exactly where the scanning has reached at that moment, the X,Y position of the pen can be resolved. This is usually achieved by the light pen causing an interrupt, at which point the scan position can be read from a special register, or computed from a counter or timer. The pen position is updated on every refresh of the screen.

The light pen became moderately popular during the early 1980s. It was notable for its use in the Fairlight CMI, and the BBC Micro. Even some consumer products were given light pens, in particular Thomson's TO7 and TO7/70 computers. Due to the fact that the user was required to hold his or her arm in front of the screen for long periods of time, the light pen fell out of use as a general purpose input device.

The first light pen was used around 1957 on the Lincoln TX-0 computer at the MIT Lincoln Laboratory, and is mentioned as the "Lincoln Wand" in the first RFC, RFC 1.

Since the current version of the game show Jeopardy! began in 1984, contestants have used a light pen to write down their wagers and responses for the Final Jeopardy! round.

Since light pens operate by detecting light emitted by the screen phosphors, some nonzero intensity level must be present at the coordinate position to be selected.

SMPS

Switched-mode power supply

A switched-mode power supply, switching-mode power supply or SMPS, is an electronic power supply unit (PSU) that incorporates a switching regulator. While a linear regulator maintains the desired output voltage by dissipating excess power in a "pass" power transistor, the SMPS rapidly switches a power transistor between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. The resulting rectangular waveform is low-pass filtered with an inductor and capacitor. The main advantage of this method is greater efficiency because the switching transistor dissipates little power in the saturated state and the off state compared to the semiconducting state (active region). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation from the higher efficiency. Disadvantages include greater complexity, the generation of high amplitude, high frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), and a ripple voltage at the switching frequency and the harmonic frequencies thereof.

SMPS can be classified into four types according to the input and output waveforms, as follows.

How an SMPS works

Block diagram of a mains operated AC-DC SMPS with output voltage regulation.

Inverter stage

The inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it inaudible to humans. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve high gain) MOSFET amplifier. MOSFETs are a type of transistor with a low on-resistance and a high current-handling capacity. Since only the last stage has a large duty cycle, previous stages can be implemented by bipolar transistors leading to roughly the same efficiency. The second last stage needs to be of a complementary design, where one transistor charges the last Mosfet and another one discharges the Mosfet. A design using a resistor would run idle most of the time and reduce efficiency. All earlier stages do not weight into efficiency because power decreases by a factor of 10 for every stage (going backwards) and thus the earlier stages are responsible for at most 1% of the efficiency. This section refers to the block marked "Chopper" in the block diagram.

Joystick

A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer. A popular variation of the joystick used on modern video game consoles is the analog stick.

The joystick has been the principal flight control in the cockpit of many aircraft, particularly military fast jets, where centre stick or side-stick location may be employed (see also Centre stick vs side-stick).

Joysticks are also used for controlling machines such as cranes, trucks, underwater unmanned vehicles and zero turning radius lawn mowers. Miniature finger-operated joysticks have been adopted as input devices for smaller electronic equipment such as mobile phones.

Joysticks can be used within first-person shooter games, but generally provide less accurate control than a combination of mouse and keyboard input.

Technical details

Most joysticks are two-dimensional, having two axes of movement (similar to a mouse), but one and three-dimensional joysticks do exist. A joystick is generally configured so that moving the stick left or right signals movement along the X axis, and moving it forward (up) or back (down) signals movement along the Y axis. In joysticks that are configured for three-dimensional movement, twisting the stick left (counter-clockwise) or right (clockwise) signals movement along the Z axis. These three axes - X Y and Z - are, in relation to an aircraft, roll, pitch, and yaw.

An analog joystick is a joystick which has continuous states, i.e. returns an angle measure of the movement in any direction in the plane or the space (usually using potentiometers) and a digital joystick gives only on/off signals for four different directions, and mechanically possible combinations (such as up-right, down-left, etc.). (Digital joysticks were very common as game controllers for the video game consoles, arcade machines, and home computers of the 1980s.)

Additionally joysticks often have one or more fire buttons, used to trigger some kind of action. These are simple on/off switches.

Some joysticks have force feedback capability. These are thus active devices, not just input devices. The computer can return a signal to the joystick that causes it to resist the movement with a returning force or make the joystick vibrate.

Most I/O interface cards for PCs have a joystick (game control) port. Modern joysticks (as of 2007) mostly use a USB interface for connection to the PC.

History

Computer port view of the Atari standard connector:

1. up
2. down
3. left
4. right
5. reserved
6. fire button
7. +5VDC
8. ground
9. not connected

Joysticks were originally controls for an aircraft's ailerons and elevators.

The name "joystick" is thought to originate with early 20th century French pilot Robert Esnault-Pelterie.^[1] There are also competing claims on behalf of fellow pilots Robert Loraine, James Henry Joyce and Mr A.E. George. The latter was a pioneer aviator who with his colleague Mr. Jobling built and flew a biplane at Newcastle, England in 1910. He is alleged to have invented the "George Stick" which became more popularly known as the joystick. The George and Jobling aircraft control column is in the collection of the Discovery Museum in Newcastle Upon Tyne, England. The joystick itself was present in early planes, though the mechanical origins themselves are uncertain.

The first electrical 2-axis joystick was probably invented around 1944 in Germany. The device was developed for targeting the glide bomb Henschel Hs 293 against ship targets. Here, the joystick was used by an operator to steer the missile towards its target. This joystick had on-off switches rather than analogue sensors, i.e. a digital joystick. The signal was transmitted from the joystick to the missile by a thin wire.

This invention was picked up by someone in the team of scientists assembled at the Heeresversuchsanstalt in Peenemünde. Here a part of the team on the German rocket program was developing the Wasserfall missile, a variant of the V-2 rocket, the first ground-to-air missile. The Wasserfall steering equipment converted the electrical signal to radio signals and transmitted these to the missile.

The Atari standard joystick, developed for the Atari 2600 was a digital joystick, with a single 'fire' button, and connected via a DE-9 connector, the electrical specifications for which was for many years the 'standard' digital joystick specification. Joysticks were commonly used as controllers in first and second generation game consoles, but then gave way to the familiar Game pad with the Nintendo Entertainment System and Sega Master System in 1985 and 86, though joysticks - especially arcade-style ones - were and are popular after-market add-ons for any console.

The joystick has found a new lease of life for flight control in the form of a 'sidestick' - a controller similar to a games joystick but which is used to control the electronics of the latest aircraft. Almost the entire family of Airbus aircraft (with the exception of the A300 and A310) up to the A380, the largest commercial aircraft in aviation, use the 'sidestick' which saves weight, improves movement and visibility in the cockpit and is said to be safer in the event of an accident than the traditional 'control yoke'.

BLUE TOOTH

Bluetooth is a wireless protocol utilizing short-range communications technology facilitating data transmission over short distances from fixed and/or mobile devices, creating wireless personal area networks (PANs). The intent behind the development of Bluetooth was the creation of a single digital wireless protocol, capable of connecting multiple devices and overcoming problems arising from synchronization of these devices. Bluetooth uses a radio technology called frequency hopping spread spectrum. It chops up the data being sent and transmits chunks of it on up to 75 different frequencies. In its basic mode, the modulation is Gaussian frequency shift keying (GFSK). It can achieve a gross data rate of 1 Mb/s. Bluetooth provides a way to connect and exchange information between devices such as mobile phones, telephones, laptops, personal computers, printers, GPS receivers, digital cameras, and video game consoles over a secure, globally unlicensed Industrial, Scientific, and Medical (ISM) 2.4 GHz short-range radio frequency bandwidth. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group (SIG). The Bluetooth SIG consists of companies in the areas of telecommunication, computing, networking, and consumer electronics.

Bluetooth vs. Wi-Fi in networking

Bluetooth and Wi-Fi have many applications in today's offices, homes, and on the move: setting up networks, printing, or transferring presentations and files from PDAs to computers. Both are versions of unlicensed wireless technology. Wi-Fi differs from Bluetooth in that it provides higher throughput and covers greater distances, but requires more expensive hardware and may present higher power consumption.

They use the same frequency range, but employ different modulation techniques. While Bluetooth is a replacement for cabling in a variety of small-scale applications, Wi-Fi is a replacement for cabling for general local area network access. Bluetooth can be taken as replacement for USB or any other serial cable link, whereas Wi-Fi is wireless Ethernet communications according to the protocol architectures of IEEE 802.3 with TCP/IP. Both standards are operating at a specified bandwidth not identical with that of other networking standards; the mechanical plug compatibility problem known with cables is replaced by the compatibility requirement for an air interface and a protocol stack.

Computer requirements

A personal computer must have a Bluetooth adapter in order to communicate with other Bluetooth devices (such as mobile phones, mice and keyboards). While some desktop computers and most recent laptops come with a built-in Bluetooth adapter, others will require an external one in the form of a dongle.

Unlike its predecessor, IrDA, which requires a separate adapter for each device, Bluetooth allows multiple devices to communicate with a computer over a single adapter.

A personal computer must have a Bluetooth adapter in order to communicate with other Bluetooth devices (such as mobile phones, mice and keyboards). While some desktop computers and most recent laptops come with a built-in Bluetooth adapter, others will require an external one in the form of a dongle.

Unlike its predecessor, IrDA, which requires a separate adapter for each device, Bluetooth allows multiple devices to communicate with a computer over a single adapter.

LCD MONITER

LCD monitor
A monitor that uses LCD technologies rather than the conventional CRT technologies used by most desktop monitors. Until recently, LCD panels were used exclusively on notebook computers and other portable devices. In 1997, however, several manufacturers began offering full-size LCD monitors as alternatives to CRT monitors. The main advantage of LCD displays is that they take up less desk space and are lighter. Currently, however, they are also much more expensive.
Why LCD?
Ever wondered why the bigger CRT screens weigh more? Blame it on technology that is used for display. A CRT monitor uses an electron gun to bombard electrons over a glass tube coated with phosphor, which glows when struck by the electron beam. While in LCDs , liquid crystals sandwiched between thin polarized sheets are used. This setup allows LCDs to be sleeker and less heavier than CRTs. They consume 1/3rd of the power of a CRT. They also emit lesser radiation than CRTs, and therefore are less stressful for eyes. So if your employees spend long hours in front of their PCs, then it's better to give them LCD monitors. There is one small drawback in LCDmonitors. The viewing angle of most LCD monitors is only 160 degrees, so if you try to view the monitor from the sides, you may not be able to see anything. Nevertheless, that's a small price to pay compared to the benefits you'll get by using them.

Plan your purchase
There are many factors to consider when choosing an LCD monitor, and it's important to spend some time on them because it's a long term investment. You may be on a tight budget or might be facing space constraints. You could have specific needs such as gaming or video editing or to put a fancy looking monitor on your office's front desk. Let's see what all needs to be considered.

Screen-Size
LCD screen sizes vary from 15 to 28 inches nowadays. Typically for routine office work, 15" LCD monitors are sufficient. However, by paying a little extra, you can also go for a 17" LCD. The catch is that when you're buying in volumes, then even a small per unit price differential can sum up to become a sizeable amount to pay. So price differential isn't the only reason to choose a bigger or smaller screen size. It's the actual need that matters. If you need it for employees who're going to use it for a single or very few applications, then a 15" LCD is sufficient. However, if the work demands working on multiple applications simultaneously, then extra screen space can be a boon for the user. If your work includes animation, then ideally a 19" or a 22" LCD is recommended, as they provide enhanced video experience. Moreover, as 22" LCDs are capable of providing full HD output, they are better suited to designers and video editors.

Aspect ratio
CRT monitors usually have an aspect ratio of 4:3. The LCD monitors too have a 4: 3 aspect ratio. However, the current trend of high-def TV, widescreens and 16:9 DVDs have made 16:9 LCDs the flavor of the season. For Xtra widescreen, 16:10 aspect ratio is also available. Widescreen monitors are capable of displaying 16:9 videos in full screen mode without cropping them. But this doesn't mean that the screen size of widescreen monitors is more than that of 4:3 ratio displays. What they gain in terms of a wide display, they lose the same in height. So a 19" LCD has the same height as a 17" LCD, even though it may look bigger due to the wide stretch. Interestingly, all monitors above 20" are available in widescreen only.

Resolution

All LCD monitors have a native resolution at which they will give you the best quality viewing. Apart from this, they would also support a few other resolutions. You need to check how many such resolutions are supported in a LCD monitor, because non-supported resolutions will result in distorted images. Most of the 4:3 LCDs have a maximum resolution of 1280 x 1024, which is appropriate for routine usage other than watching high-def (i.e. 16:9) videos. The widescreen LCDs come with resolution of 1440 x 900, 1680 x 1050 or 1920 x 1200 pixels and that makes them appropriate for high-def video playback as well as other tasks. Most of the games these days also come with support for widescreen resolution display.

Viewing Angle
This is one of the most crucial parameters. Both the horizontal and vertical viewing angles must be checked. With LCDs, the display appears perfect when you sit right in front but deteriorates as you move sideways. So, always buy the one that has the maximum viewing angle. For best viewing experience, we suggest a monitor having a viewing angle of 160 degrees and above.

Adjustments
LCD monitors are light and portable and usually need to be attached to a separate stand. There are LCD monitors that allow the display screen to be tilted by a certain angle or be swiveled and rotated by a certain angle. This aspect is more important for an office than a home user.

Dot Pitch
Dot Pitch refers to the distance between each pixel or pocket. The lesser the space between each pocket the crispier the image and better picture the you will get. 0.22 mm is the value of dot pitch which is recommended for intense graphics use while for normal use anything between 0.26-0.30 mm will suffice.

Auto-Adjust

This is one of the most important features of an LCD monitor. In CRTs, the display moves out of screen whenever there is a change in resolution. However, the auto-adjust feature ensures that this doesn't happen no matter what. While most monitors have the auto-adjust feature, it's still advisable to check before buying.

Pivot display
Some LCD monitors have the feature to pivot the display panel from landscape to portrait mode. This can be done by using the supplied software that comes with the monitor; it rotates and reforms the image to be displayed in the new orientation. Additionally, monitors that generally have this feature can be rotated clockwise (by 90 degree) to facilitate work in the portrait mode. This feature can be useful when you're working on long documents, you needn't scroll down while viewing a long webpage.

Inputs
LCDs work best with the digital input, so if the LCD is attached via a D-sub port then the digital data is converted to analog and then at the monitor it is converted back to digital format which leads to loss in signal quality. The DVI interface eliminates this conversion process and directly transmits digital signal to provide lossless display. DVI with HDCP input is the best, HDCP encrypts the transmission of digital content from the computer and the monitor that supports HDCP can then decrypt the transmitted data without any loss in the integrity of the transmitted content. So, the LCDs having DVI with HDCP are recommended, even if they cost you a bit more. Monitors above 22" are capable of displaying full HD content, and some of them even come with HDMI input that is capable of transmitting HD content without any loss of quality. Infact, now there are graphics cards too that come with HDMI output.

On-Screen display
Similar to CRTs, LCDs also need to be adjusted for brightness, contrast, and color. Thus LCDs also come with adjustment keys that provide OSD controls. One should check that these controls are easy to use, quick to learn, and the keys on front panel are not flimsy. Some manufacturers also provide an OSD lock control, which means that no one can alter your settings. If you want this feature then it is advisable to check the OSD lock feature: how easy it is to use and reset.

Audio
Apart from adding a visual element to your desktop, LCDs also offer full multimedia capabilities. A number of monitors come with onboard speakers which are perfect for casual listening. In general they don't have quite high volume, plus sometimes the output at max volume becomes shrilling. Hence, the speakers must be checked by listening to songs or watching videos on the LCD at max volume. Some LCD screens come with headphone jack either on the side or at the back of the screen. So, if your work is such that you have to be constantly connected with the headphones, then an LCD with the headphone jack option is a sensible option.
Response time
This refers to the amount of time it takes for the crystals in the LCD monitor to turn on and off. The lower the response time, the less ghosting and streaking would appear on the monitor. The response time of LCD varies between 2 and 16 ms. For general word processing and Internet browsing an LCD monitor with 8–16 ms latency would not be an issue. However, for watching videos and playing games, the monitor should have a response time of 5 ms or less to avoid blurring of screen or visible ghosting.

Other factors
These are mainly user-specific depending on the special requirements of the user.

USB ports
Some LCD monitors provide USB ports that can be handy if you have many devices to connect.

Wall mounting
If you want to put a LCD monitor in a public place, such as your reception, then this feature comes in handy.

Dead pixels:
The nemesis of LCDs Sometimes, individual liquid crystal cells get permanently stuck on or off in an LCD during manufacturing or transportation. A dead pixel is a tiny colored or black dot that does not change along with other cells and stands out in each program. There are several methods on Internet to get rid of dead pixels, but they are not 100 per cent fool proof.

LCD monitor TV
A new crop of LCD monitor TVs is coming from manufacturers like LG, BenQ, ViewSonic and Samsung. Their sizes range from 19" to 28". These monitors have the standard D-Sub and DVI ports and also have component, composite, and HDMI connectivity options. While buying an LCD it is important that you try it out.

Viewing angle, contrast, and brightness are all factors that you can decide upon only after seeing the LCD in action. Always try to check the LCD with the widest possible viewing angle. This would also ensure that you can ask for a different unit if dead pixels are present.

DVD-RAM

DVD-RAM (DVD–Random Access Memory) is a disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders and personal video recorders since 1998.

Introduction

Currently there are three competing technologies for rewritable DVDs: DVD-RAM, DVD+RW and DVD-RW. DVD-RAM is considered a highly reliable format, as the discs have built-in error control and a defect management system. Therefore, DVD-RAM is perceived to be better than the other DVD technologies for traditional computer usage tasks such as general data storage, backup and archival, though the Mount Rainier Format standard for DVD+/-RW (and CD-R, CD-RW, DVD+/-R) somewhat lessens the DVD-RAM format's perceived advantage. Curiously, DVD-RAM has a larger presence in camcorders and set-top boxes than in computers, although the DVD-RAM's popularity in these devices can be explained by the fact that it is very easily written to and erased, which for example allows extensive in-camera editing.

The on-disc structure of DVD-RAMs is closely related to hard disk and floppy disk technology, as it stores data in concentric tracks. DVD-RAMs can be accessed just like a hard or floppy disk and usually without any special software. DVD-RWs and DVD+RWs, on the other hand, store data in one long spiral track and require special packet reading/writing software to read and write data discs. It is a common misconception that DVD-RAM uses magneto-optical (MO) technologies, since both DVD-RAM and MO have numerous rectangles on the disc surface. However, DVD-RAM is a pure phase change medium, similar to CD-RW or DVD-RW.

DVD-RAM Cartridge types

Size	Bare Disc		Non-removable Cartridge		Removable Cartridge		Empty/No Cartridge
sides	single	double	single	double	single	double	single	double
12 cm	yes (type 0)	none	type 1	type 1	type 2	type 4	type 3	type 5
8 cm	yes (type 0)	none	none	none	type 7	type 6	type 9	type 8

Specification

Since the Internationale Funkausstellung Berlin 2003 the specification is being marketed by the RAM Promotion Group (RAMPRG), built by Hitachi, Toshiba, Maxell, LG Electronics, Matsushita/Panasonic, Samsung and Teac.The specification distinguishes between

• DVD-RAM version 1.0, recording speed 1x
  • Single-sided, one layer discs with a capacity of 2.58 GB
  • Double-sided one layer discs with a capacity of 5.16 GB
• DVD-RAM version 2.0, recording speed 2x
  • Single-sided, one layer discs with a capacity of 4.7 GB
  • Double-sided one layer discs with a capacity of 9.4 GB
• DVD-RAM version 2.1/Revision 1.0, recording speed 3x
• DVD-RAM version 2.2/Revision 2.0, recording speed 5x
• DVD-RAM version 2.3/Revision 3.0, recording speed 6x max
• DVD-RAM version 2.4/Revision 4.0, recording speed 8x max
• DVD-RAM version 2.5/Revision 5.0, recording speed 12x max
• DVD-RAM version 2.6/Revision 6.0, recording speed 16x max

Physically smaller, 80 mm in diameter, DVD-RAM discs also exist with a capacity of 1.46 GB for a single-sided disc, but they are uncommon. DVD-RAMs were originally solely sold in cartridges; recent DVD recorders can work with discs either with or without cartridge, and many devices do not support cartridges at all. Discs can be removed from cartridges for use with these drives.

Compatibility

A DVD-RAM Type 2.

Many operating systems like Mac OS (Mac OS 8.6 up to Mac OS X), Linux and Microsoft Windows XP support DVD-RAM operation directly, while earlier versions of Windows require device drivers or the program InCD.

Windows XP can only write directly to FAT32-formatted DVD-RAM discs. For UDF-formatted discs, which are considered faster, compatible device drivers or software such as InCD or DLA are required. Windows Vista can natively access and write to UDF-formatted DVD-RAM discs. This is a non-issue with Linux however, which allows the use of virtually any file system of the multitude that ship with the operating system, including UDF. It is even possible to use the ext3 file system on a DVD-RAM disc. Even though it is possible to use any file system one likes, only very few perform well on DVD-RAM. This is because some file systems frequently over-write data on the disc and the table of contents is contained at the start of the disc.

Mac OS up to 9.2 (Mac OS Classic) can read and write HFS-, HFS Plus-, FAT-, and UDF-formatted DVD-RAM discs directly. Mac OS X officially supports DVD-RAM formatting and writing operations. (See [1].)

Many DVD standalone players and recorders do not support DVD-RAM, especially older or cheaper versions. However, within "RAMPRG" (the DVD-RAM Promotion Group) there are a number of well-known manufacturers of standalone players and recorders that do support DVD-RAM. Panasonic, for instance, has a range of players and recorders which make full use of the advantages of DVD-RAM. There are also a number of video cameras that use DVD-RAM as the recording media.

Some DVD players with hardware DVD-RAM capability are sold without DVD-RAM support. As a specific example, Dell uses the TS-L632D drive manufactured by TSST in some of its laptop computers without DVD-RAM capability. However it is possible, with some difficulty, to replace the firmware with a non-Dell version which supports DVD-RAM.

The newest DVD-RAM Specification, DVD-RAM2 (also called RAM2), is not compatible with DVD drives that do not specifically support reading DVD-RAM2 discs.

Advantages of DVD-RAM

• Long life — without physical damage, data is retained for an estimated 30 years minimum. Ideal for video evidence recording in CCTV applications amongst many other uses.
• Can be rewritten over 100,000 times (DVD±RW can be rewritten approx. 1,000 times). Faster DVD-RAMs support fewer rewrites (3x speed: 100,000, 5x speed: 10,000)^{[citation needed]}, but still more than DVD+RW or DVD-RW. (These are theoretical numbers. In practice they could be smaller depending on the drive, the treatment of the disc and the file system. In practice, a domestic DVD recorder can rewrite a disk only 300 times. Note also that some areas of the disc, e.g. directory, can be written many times without the user perceiving multiple writes.)
• Reliable writing of discs. Verification done in hardware by the drive, so post-write verification by software is unnecessary. Software verification is disabled in all current DVD Video Recorders.
• Disc defect management safeguards data.
• Suitable for archival storage.^[2][3]
• DVD-burning software may not be required — discs can be used and accessed like a removable hard disk. Mac OS (8.6 or later) supports DVD-RAM directly. Windows XP supports DVD-RAM directly for FAT32-formatted discs only. Windows Vista is able to write directly to both FAT32- and UDF-formatted DVD-RAM discs from within Windows Explorer. Device drivers or other software are needed for earlier versions of Windows which do not support UDF, or any format, on DVD-RAM.
• Arguably easier to use than other DVD technology.
• Very fast access of small files on the disc.
• Small 2 KB disc block size wastes less space when writing small files.
• Finalization not necessary. This is an attribute of the VR recording mode and is available on other media such as DVD-RW.
• Media available with or without protective cartridges; can be used in the cartridge by many devices.
• In some video recorders DVD-RAM can be written to and read at the same time, allowing one program to be recorded and a different one, or an earlier part of the same one (time slip recording), to be viewed at the same time. This is an attribute of the VR mode recording mode and is possible, although only at lower bit rates, on other media such as DVD+RW.
• Supported by some high-end security digital video recorders, such as the Tecton Darlex, as a secure export medium. 30 year retention makes this an ideal format for evidence.
• Holds more data when using Double Sided discs than dual-layer DVD+RW and DVD-RW, 9.4GB for DVD-RAM vs 8.5GB for DVD+RW DL and DVD-RW DL.
• Has write-protect tabs to prevent accidental deletion when used in a cartridge.

TV tuner card

A TV tuner card is a computer component that allows television signals to be received by a computer. Most TV tuners also function as video capture cards, allowing them to record television programs onto a hard disk.

Variants

A DVB-S2 tuner card

D-Link external TV tuner

TV tuners are available in a number of different interfaces: as PCI-bus expansion card, PCIe (PCI Express) bus or USB devices. Ethernet-connected devices also exist.(HDHomeRun) In addition, some video cards double as TV tuners, notably the ATI All-In-Wonder series. The card contains a tuner and an analog-to-digital converter (collectively known as the analog front end) along with demodulation and interface logic. Some very cheap cards lack an onboard processor and, like a Winmodem, rely on the system's CPU for demodulation.

There are currently four kinds of tuner card on the market:

Analog TV tuners

Cheaper models output a raw video stream, suitable for real-time viewing but ideally requiring some sort of compression if it is to be recorded. More expensive models encode the signal to Motion JPEG or MPEG, relieving the main CPU of this load. Many cards also have analog input (composite video or S-Video) and many also provide FM radio reception.

Digital TV tuners

Digital TV is broadcast as an MPEG-2 stream, so no encoder is necessary; instead, the digital cards either provide the whole MPEG transport stream or extract the individual (audio and video) elementary streams.

Hybrid tuners

A hybrid tuner has one tuner that can be configured to act as an analog tuner or a digital tuner. Switching in between the systems is fairly easy, but can not be done "on the fly". The card operates as a digital tuner or an analog tuner until reconfigured.

Combo tuners

This is similar to a hybrid tuner, except there are two separate tuners on the card. One can watch analog while recording digital, or vice versa. The card operated as an analog tuner and a digital tuner. The advantages over two separate cards are cost and utilization of expansion slots in the computer. As many regions around the world convert from analog to digital broadcasts, these tuners are gaining popularity.

Like the analog cards, the Hybrid and Combo tuners can have specialized chips on the tuner card to perform the encoding, or leave this task to the CPU. The tuner cards with this 'hardware encoding' are generally thought of as being higher quality. The small USB tuner stick have become more popular in 2006 and 2007 and are expected to increase in popularity. These small tuners generally do not have hardware encoding due to size and heat constraints.

While most TV tuners are limited to the radio frequencies and video formats used in the country of sale, many TV tuners used in computers use DSP, so a firmware upgrade is often all that's necessary to change the supported video format. Many newer TV tuners have flash memory big enough to hold the firmwares for decoding several different video formats, making it possible to use the tuner in many countries without having to flash the firmware. However, while it is generally possible to flash a card from one analog format to another due to the similarities, it is generally not possible to flash a card from one digital format to another due to differences in decode logic necessary.

Many TV tuners can function as FM radios: this is because there are similarities between broadcast television and FM radio. The FM radio spectrum is close to (or even inside) that used by VHF terrestrial TV broadcasts. And many broadcast television systems around the world use FM audio. So listening to an FM radio station is simply a case of configuring existing hardware.

Video card

A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to generate and output images to a display. It operates on similar principles as a sound card or other peripheral devices.

The term is usually used to refer to a separate, dedicated expansion card that is plugged into a slot on the computer's motherboard, as opposed to a graphics controller integrated into the motherboard chipset. An integrated graphics controller may be referred to as an "integrated graphics processor" (IGP).

Some video cards offer added functions, such as video capture, TV tuner adapter, MPEG-2 and MPEG-4 decoding or even FireWire, mouse, light pen, joystick connectors, or even the ability to connect multiple monitors.

A common misconception regarding video cards is that they are strictly used for Video games; a misconception that companies take advantage of in order to sell their products by advertising their products as if they were in fact video consoles. Video cards instead have a much broader range of capability. Being specialized for video output Video Cards improve what a computer monitor displays. As well, they play a very important role for Graphic Designers and 3D Animators, who tend to require optimum displays for their work as well as faster rendering in order to efficiently tone up their work.

Video cards are not used exclusively in IBM type PCs; they have been used in devices such as Commodore Amiga (connected by the slots Zorro II and Zorro III), Apple II, Apple Macintosh, Atari Mega ST/TT (attached to the MegaBus or VME interface), Spectravideo SVI-328, MSX, and in video game consoles.

Graphics processing unit (GPU)

Main article: Graphics processing unit

A GPU is a dedicated graphics microprocessor optimized for floating point calculations which are fundamental to 3D graphics rendering. The main attributes of the GPU are the core clock rate, which typically ranges from 250 MHz to 850 MHz, and the number of pipelines (vertex and fragment shaders), which translate a 3D image characterized by vertices and lines into a 2D image formed by pixels.

[edit] Video BIOS

The video BIOS or firmware contains the basic program that governs the video card's operations and provides the instructions that allow the computer and software to interface with the card. It may contain information on the memory timing, operating speeds and voltages of the graphics processor and RAM and other information. It is sometimes possible to change the BIOS (e.g., to enable factory-locked settings for higher performance) although this is typically only done by video card overclockers, and has the potential to irreversibly damage the card.

[edit] Video memory

Type	Memory clock rate (MHz)	Bandwidth (GB/s)
DDR	166 - 950	1.2 - 30.4
DDR2	533 - 1000	8.5 - 16
GDDR3	700 - 1800	5.6 - 54.4
GDDR4	1600 - 2400	64 - 156.6
GDDR5	3000 - 3800	130 - 230

If the video card is integrated in the motherboard, it may use the computer RAM (lower throughput). If it is not integrated, the video card will have its own video memory, called Video RAM. The memory capacity of most modern video cards range from 128 MB to 2.0 GB^[8]. Since video memory needs to be accessed by the GPU and the display circuitry, it often uses special high speed or multi-port memory, such as VRAM, WRAM, SGRAM, etc. Around 2003, the video memory was typically based on DDR technology. During and after that year, manufacturers moved towards DDR2, GDDR3 and GDDR4 even GDDR5 utilized most notably by the ATI Radeon HD 4870. The memory clock rate in modern cards are generally between 400 MHz and 2.4 GHz.

Video memory may be used for storing other data as well as the screen image, such as the Z-buffer, which manages the depth coordinates in 3D graphics, textures, vertex buffers, and compiled shader programs.

[edit] RAMDAC

Random Access Memory Digital-to-Analog Converter. RAMDAC takes responsibility for turning the digital signals produced by the computer processor into an analog signal which can be understood by the computer display. Depending on the number of bits used and the RAMDAC data transfer rate, the converter will be able to support different computer display refresh rates. With CRT displays, it is best to work over 75 Hz and never under 60 Hz, in order to minimise flicker.^[9] (With LCD displays, flicker is not a problem.) Due to the growing popularity of digital computer displays and the migration of some of its functions to the motherboard, the RAMDAC is slowly disappearing. All current LCD and plasma displays and TVs work in the digital domain and do not require a RAMDAC. There are few remaining legacy LCD and plasma displays which feature analog inputs (VGA, component, SCART etc.) only; these do require a RAMDAC but they reconvert the analog signal back to digital before they can display it, with the unavoidable loss of quality stemming from this digital-to-analog-to-digital conversion.^{[citation needed]}

[edit] Outputs

The most common connection systems between the video card and the computer display are:

HD-15	Analog-based standard adopted in the late 1980s designed for CRT displays, also called VGA connector. Some problems of this standard are electrical noise, image distortion and sampling error evaluating pixels.
DVI	Digital-based standard designed for displays such as flat-panel displays (LCDs, plasma screens, wide High-definition television displays) and video projectors. It avoids image distortion and electrical noise, corresponding each pixel from the computer to a display pixel, using its native resolution.
Video In Video Out (VIVO) for S-Video, Composite video and Component video	Included to allow the connection with televisions, DVD players, video recorders and video game consoles. They often come in two 9-pin Mini-DIN connector variations, and the VIVO splitter cable generally comes with either 4 connectors (S-Video in and out + composite video in and out) or 6 connectors (S-Video in and out + component PB out + component PR out + component Y out (also composite out) + composite in).

9-pin VIVO for S-Video (TV-out), DVI for HDTV and HD-15 for VGA outputs.

[edit] Other types of connection systems

Composite video	Analog system, with lower resolution. It uses RCA connector.
Component video	It has three cables, each with RCA connector (YCBCR); it is used in projectors, DVD players and some televisions.
DB13W3	An analog standard once used by Sun Microsystems, SGI and IBM.
HDMI	An advanced digital audio/video interconnect released in 2003, and is commonly used to connect game consoles and DVD players to a display. HDMI supports copy protection through HDCP.
DisplayPort	An advanced license and royalty-free digital audio/video interconnect released in 2007. DisplayPort intends to replace VGA and DVI for connecting a display to a computer.

External Hard Disk

External

hard disk

drive

An external hard disk drive is a type of hard disk drive which is externally connected to a computer, and may be portable. External hard disk drives are connected to the computer using a cable which is compatible with Small Computer System Interface (SCSI), Integrated Drive Electronics (IDE), Universal Serial Bus (USB), IEEE 1394 (Firewire), CAT-3 or CAT-5 cable (Ethernet), eSATA or other bus standards.

Structure and design

The internal structure of external hard disk drives is similar to normal hard disk drives; in fact, they include a normal hard disk drive which is mounted on a disk enclosure. ^[5] Nevertheless, the design of external hard disk drives is more targeted at portability, which can be roughly summarized as cost per gigabyte. In the PC Magazine's top 10 external hard drives chart, the cost per gigabyte value varied between 0.3 to 0.5 USD, approximately.^[6] For the same reason, high capacity external hard disk drives (which weigh more) were for a time less common, although external hard disk drives with more than 500 GB of storage capacity are now commonly manufactured.

Although external hard disk drives are intended to be portable, the data cannot be secured on them due to their insufficient shock protection ^[7] especially compared to digital portable media storage devices such flash memories and memory cards. Nonetheless, external hard disk drives cost less than memory cards or flash memories of the same storage, and are the only portable media storage options available in the size of hundreds of gigabytes.

File system, partition, and operating system

Most external hard drives are compatible with the three major operating systems: Windows, Mac OS (Unix), and Linux. On each of these OSs, you have tools for disk formatting (and maybe journaling), and partitioning. Also, you can install the operating system onto these hard drives, thus gaining the capability to boot into them and run programs or applications on a computer.

These external hard disks are also able to run different file systems, such as Mac OS X Extended (Journaled), FAT, and NTFS. The option of using different operating systems and file systems on different partitions

External hard disks can be partitioned and formatted using 'Disk Management Console' under Windows 2000, XP, and Vista, 'Disk Utility' and 'BootCamp' under Mac OS X or 'Gparted', and 'Qtparted' under Linux.