Computer Peripherals: Definition, Types and Technologies

Posted on Jan 4, 2025 in Geology

1. Definition and Types of Peripherals

Peripherals are units or devices through which a computer communicates with the external world. They also include systems that store information, such as main memory. They allow input/output (I/O) operations of complementary data to the processes of the CPU. Peripherals can be classified into five main categories:

  • Input Peripherals: Capture and send data to the device for processing.
  • Output Peripherals: Display or project information from the computer to the outside world. They show information to alert, communicate, plan, or give the user some information. They convert electrical impulses into user-readable information.
  • Input/Output (I/O) Peripherals: Introduce external data to the computer for processing by the CPU.
  • Storage Peripherals: Store data and information for long periods. RAM is not considered a storage peripheral because it is volatile and temporary memory.
  • Communication Peripherals: Allow machines or other computers to communicate, work together, or send and receive information.

2. Webcam Summary

A webcam is a small digital camera connected to a computer. It captures and transmits images over the internet. Some webcams have autonomy and only need a network access point, either Ethernet or wireless. Webcams are differentiated from network cameras by their software. A webcam takes a frame from the camera periodically and sends it to be displayed elsewhere. For video, a webcam needs to reach a rate of 15 to 30 frames per second. Webcams consist of a lens, a sensor, and the necessary circuitry. Lenses can be made of plastic, which is the most common.

3. What is a Scanner? Types

A scanner is a peripheral used to convert printed images into digital format using light. Scanners can have accessories such as an automatic sheet feeder or an adapter for slides and transparencies. Once a digital image is obtained, defects can be corrected, specific areas can be cropped, and the image or text can be digitized using OCR technology. There are several types of scanners. The most common today are flatbed scanners.

Flatbed Scanner

A flat glass surface where the document is placed for scanning. An arm moves along the capture area. This mobile arm contains the light source and the photosensor (usually a CCD).

Orbital Scanner

Used to scan books or digital copies of documents that are old or valuable. These scanners consist of a camera mounted on an arm that takes pictures of the desired document. Its main advantage is that books do not need to be fully opened.

Drum Scanner

These scanners reproduce the original document faithfully and produce high-resolution digitalizations (up to 4,000 dpi optical mode) and quality. Their main problems are the slow scanning speed and that they are not suitable for fragile paper documents. They also require a high level of operator skill and are expensive.

Handheld Scanner

These are dragged across the surface of the image to be scanned. They require a firm hand, and uneven speed can produce distorted images. A light on the scanner indicates if the scan was too fast.

4. Scanner Quality and How to Scan

The color depth depends on the characteristics of the vector scan, which is normally at least 24 bits. 48-bit provides better quality or color depth. Another relevant parameter is the resolution, measured in pixels per inch (DPI). Manufacturers often refer to the interpolated resolution, which is higher thanks to software interpolation. The density range is also important. A scanner with a high density range can reproduce highlights and shadows in a single pass. Scanning can be done in grayscale or color. Most scanners can do double-sided scanning at high speeds (20 to 150 pages per minute). Sophisticated scanners have firmware that eliminates accidental marks. Scanned data is usually compressed. Most scanned documents are converted into editable files using OCR technology. Using ISIS and TWAIN drivers, the document is scanned into TIFF format, and then moved to a word processor.

5. What is a Digital and Analog Converter?

An analog-to-digital converter (ADC) is an electronic device that transforms analog signals into digital signals. These converters have two or more input signals and determine which signal will be converted. The device establishes a relationship between the input (analog signal) and the output (digital signal) depending on its resolution. The resolution can be determined by knowing the maximum value of the input information and the maximum number of output binary digits. The analog-to-digital conversion consists of taking periodic measurements of the range (voltage) of a signal, rounding its values to predefined voltage levels, and registering them as integers in memory.

6. Touchscreen: What is it and What is it Used For?

A touchscreen is a display that allows direct interaction with a device through contact with its surface. It acts as an output peripheral by showing results and as an input peripheral by allowing data entry. Touchscreens are popular in industry and other situations, such as museums, where mice and keyboards are not satisfactory. They provide intuitive, fast, and accurate interaction with the content.

7. What is a Graphics Card? GPU. Video Memory. Interfaces. Types

A graphics card is an expansion card that processes data from the CPU and transforms it into a format that can be displayed on an output device, such as a monitor. Most graphics cards are compatible with IBM PC computers. The GPU is a processor that handles graphics processing, offloading work from the central processor. It is optimized for floating-point operations and 3D functions. The most important specifications of a graphics card refer to the GPU. Video memory (VRAM) ranges from 128 MB to 1 GB. In 2006, memory was based on DDR technology, including DDR2, GDDR3, GDDR4, and GDDR5. The memory clock frequency was between 400 MHz and 1.8 GHz. The video adapter’s buffer manages the depth coordinates of images in 3D graphics.

8. Graphics APIs and Effects

Graphics APIs abstract the complexity and diversity of graphics cards. Two important APIs are:

  • Direct3D: Launched by Microsoft in 1996, it is part of the DirectX library. It only works on Windows and is used in most commercial Windows video games.
  • OpenGL: Created by Silicon Graphics in the early 1990s, it is free, open, and multiplatform. It is mainly used in CAD, virtual reality, and flight simulation applications. It has been displaced in the video game market by Direct3D.

Some common technical effects generated by graphics cards include:

  • Antialiasing: Avoids the aliasing effect, which makes curves and steep lines appear jagged due to the finite spacing of monitor pixels.
  • Shaders: Process vertices and pixels for lighting effects, natural surfaces, and layers.
  • HDR: Represents a wide range of intensity levels in scenes (from direct light to dark shadows).
  • Texture Mapping: Adds details to surfaces without increasing the complexity of the models.
  • Motion Blur: The effect of smearing due to the speed of a moving object.
  • Depth Blur: The effect of smearing due to the distance of an object.
  • Lens Flare: Imitation of the reflections of light sources on the camera lens.
  • Fresnel Effect: (Specular reflection) The reflection depends on the angle of incidence of light on a surface. A larger angle results in more reflection.

9. Monitors: Summary and Types

Monitors display information from the computer. Since the first green phosphor monitors, technology has evolved along with graphics cards. Today, a computer without a color monitor is unthinkable. There are several types of monitors:

CRT

CRT monitors translate and display images from the graphics card. They are similar to conventional televisions. They use a cathode ray tube with an electron gun that constantly shoots electrons against a phosphor-coated screen.

LCD

LCD monitors are thin, flat glass displays formed by a number of color or monochrome pixels placed in front of a light source or reflector.

TFT-LCD

TFT-LCD is a variant of LCD that uses thin-film transistor (TFT) technology to improve image quality. TFT-LCDs are a type of active matrix display. They are used in televisions, flat-screen displays, and projectors.

Plasma

Plasma displays are used in large flat-screen TVs (around 37 inches or 940 mm). They have many tiny glass cells filled with a mixture of noble gases (neon and xenon).

OLED

OLEDs are based on an electroluminescent layer formed by organic components that emit light when stimulated electrically. The main advantages of OLEDs are lower cost, higher scalability, better colors, contrasts, and brightness, a wider viewing angle, lower consumption, and flexibility. The degradation of OLED materials has limited their use.

10. What are Sound Cards? Internal or External?

A sound card is an expansion card that allows a computer to input and output audio under the control of a program called a driver. The sound quality does not depend on whether the card is internal or external. The market has shifted towards external sound cards that offer high-quality products and high performance, although at a higher price.

11. Main Technical Characteristics of Sound Cards: Bits, kHz, etc.

A sound chip contains a digital-to-analog converter, which translates digital waves into analog signals and vice versa. Sound cards take samples of sound at 16 bits. The number of bits defines the position of the speaker. The more positions that can be represented, the better the sound signal. Domestic sound cards can work with a resolution of 44.1 kHz, and many can reach 48 kHz. Semi-professional cards work mostly with 48 kHz, and some even with 50 kHz. Professional cards can reach around 100 kHz.

12. Internal and Logical Structure of a Disk

  • Disk: Each of the platters inside a hard disk.
  • Face: Each of the two sides of a platter.
  • Head: The number of read/write heads.
  • Track: A circumference on a side of a platter. Track 0 is on the outer edge.
  • Cylinder: A set of tracks that are vertically aligned (one on each side).

Sector: Each division of a track. The size of a sector is not fixed, but it is usually 512 bytes. The number of sectors per track was fixed, which meant that space was wasted on the outer tracks. Inside the disk are:

  • The boot record (the first sector), which contains the partition table.
  • Partitions, where different file systems can be placed, such as FAT, NTFS, or Linux file systems.

13. Standard Hard Drive Interfaces: IDE and SCSI

The interface is an electronic component that manages the data flow of the disk system. It is responsible for how data is stored, its transfer rate, speed, etc. The most important interfaces are:

IDE Standard

Its main characteristic was the implementation of the controller on the hard drive itself. It allowed transfer rates of 4 MB per second, which simplified the installation and configuration process of hard drives. It met the market’s demands for a time.

Enhanced IDE (EIDE)

Improved flexibility and performance. It increased capacity to 8.4 GB and the transfer rate to 10 MB per second. It also implemented translation systems for physical parameters.

SATA (Serial ATA)

A new standard from 2004 that uses a serial bus for data transmission. It is faster than IDE. There are two versions: SATA 1 with up to 150 MB/s (18.75 MB/s) and SATA 2 with up to 300 MB/s (37.5 MB/s) transfer rates.

SCSI Standard

The SCSI interface (Small Computer System Interface) has been traditionally used in professional environments where performance, flexibility, and reliability are important. The SCSI bus is separate from the system bus, avoiding the limitations of the PC bus. It allows connecting up to 7 SCSI devices (8 if the controller is included). It can connect any type of device (scanners, printers, CD-ROMs, removable drives, etc.). SCSI performance does not depend on the system bus.

14. CD Recording: How is a CD Recorded?

A CD is a digital optical storage medium. When a CD-R is recorded, its surface is melted. Data is stored in a code that the reader can interpret. The recorder creates pits and lands by changing the reflectivity of the CD surface. Pits are areas where the laser has more power, and lands are areas with higher reflectivity. A pit requires a surface temperature of 250°C.

15. Differences Between CD, DVD, and Blu-ray Technologies

CDs use an infrared laser with a wavelength of 780 nanometers (nm), while DVDs use a laser with a wavelength of 635 or 650 nm. CD players use a lens with a numerical aperture of 0.5, while DVD players use a lens with a numerical aperture of 0.6. Blu-ray discs use a blue laser with a wavelength of 405 nm. This allows for a smaller and more focused light beam. The tracks and holes are smaller, reflecting the laser as zeros and ones.

  • CD: 120 mm diameter, 74-80 minutes of audio, 650-700 MB of data. 80 mm diameter (mini-CD or CD pocket) can store 21 minutes of music or 210 MB of data.
  • DVD: DVD-5 4.7GB, DVD-9 8.5GB, DVD-10 9.4 GB, DVD-17 18 GB.
  • Blu-ray: Up to 25 GB per layer, and 50 GB for dual-layer discs.

16. Flash Memory: What is it and What is it Used For?

Flash memory is a type of EEPROM memory that allows multiple memory positions to be written or deleted in the same programming operation using electrical impulses. Flash memory operates at higher speeds than previous technologies. It is used in small devices such as mobile phones, PDAs, small appliances, digital cameras, and portable audio players.

17. Modem: What is it?

A modem is a peripheral that connects to a computer and converts its binary language (digital signal) into audio tones (analog signal). These audio tones can be sent over telephone lines. At the other end, another modem converts the tones back into binary code. This process is called modulation-demodulation (modem is an abbreviation).

18. ADSL Modem

ADSL is a type of DSL line. It uses a symmetrical copper pair that carries the conventional telephone line. It can reach up to 5.5 km from the central office. It is a broadband internet access technology that uses higher frequencies than those used in conventional telephone conversations (300-3800 Hz). The ADSL modem or router performs the modulation.

19. Network Card: General Summary

A network card allows communication between computers and allows sharing resources (hard disks, CD-ROMs, printers, etc.). Network cards are also called network adapters or NICs (Network Interface Card). There are different types of adapters depending on the type of cable or network architecture (thin coax, thick coax, token ring, etc.). The most common type is Ethernet, which uses an RJ-45 connector. Gigabit Ethernet and 10 Gigabit Ethernet are also being used, which use category 6, 6e, and 7 twisted-pair cables.

Wireless Network Card (Wireless)

Wireless NICs come in different varieties depending on the standard they adhere to, usually 802.11a, 802.11b, and 802.11g. The most popular are 802.11b, which transmits at 11 Mbps with a range of 100 meters, and 802.11g, which transmits at 54 Mbps.

Bluetooth Card

A Bluetooth card allows a PC to communicate with any Bluetooth peripheral.

20. Scanner Quality and How to Scan

The color depth depends on the characteristics of vector scanning (the first of the basic characteristics that define the quality of the scanner) that would normally be at least 24 bits. With 48 bit you get a better quality or color depth. Othermost relevant parameters of the quality of a scanner is resolution, measured in pixels per inch (DPI). Manufacturers of scanners, rather than referring to the actual optical resolution scanner, prefer to refer to the interpolated resolution, which is much higher thanks to software interpolation. The third most important parameter for providing a quality scanner is the density range. If the scanner has a high density range, means it is capable of playing with shadows and highlights a single pass. Scanning is done in gray scale, although it is possible to do it in color. Most are capable of two-sided scanning at maximum speed (20 to 150 pages per minute). The most sophisticated have incorporated some firmware scanning clean eliminating accidental marks. Normally, the scanned data is compressed on the fly. Most scanned documents are converted into editable files using OCR technology. Using ISIS and TWAIN driver scans the document into TIFF format, to move scanned pages to a word processor, which stores the corresponding file.