A Guide to Computer Expansion Cards: Types and Functions
Graphics Cards
Types of Video Memory
DRAM: Were the predominant channels for a long time. Provide low output values.
EDO DRAM: Have been used for quite some time, less expensive than VRAM, is used in middle-low-end cards.
VRAM: You can write to it and read it at the same time. It is much faster than the previous, but memory is a type face.
WRAM: Is a modified version of the VRAM that improves performance and is cheaper.
SGRAM: Currently the most widely used because they offer very good performance. It is the most used in mid-range cards.
MDRAMA: It is a newer type of memory, faster than the previous ones used in high-end graphics cards.
3D Graphics Accelerator Cards
Currently, almost all graphics cards have support for 3D, which can represent objects in three dimensions. However, these cards work much more slowly than cards specially equipped for this purpose.
The 3D graphics accelerator cards are inserted into a PCI slot and communicate with the graphics card via an external cable. The monitor is also connected directly to the 3D card. These cards are often used for applications with highly realistic animations, for example, games.
Sound Cards
A sound card adds the ability to record and play sounds from internal or external sources to the computer. Its main function is to convert analog sounds, that come from, for example, a microphone, to a digital format, so that they may be added as files on your computer.
Sound Measurement
To measure sound, we have to take into account the quality of sampling, 16 or 32 bits, which is the value of the amplitude or height of the wave at a number of binary bits. This operation is done from time to time, taking several points per second called frequency measured in Hertz (dots per second). The sound may be mono or stereo, single-channel or two-channel, or two waves, one for each speaker. Size = number of channels * sound quality sampling * frequency * duration (Sec).
Video Capture Cards
There are cards with which we can watch TV on our computer monitor in full screen or in a window while doing other tasks. Some of these cards have FM radio tuners and remote controls. Generally, these TV tuner cards can also capture video, meaning you can store a video sequence with its corresponding sound in a file on your hard drive. Video capture can be made from:
- A television channel.
- A conventional video camera.
- A webcam-type camera.
However, the resolution in these cards is somewhat limited. There are other special cards for video capture, both analog and digital video cameras. Some are internal and some are external. These cards can capture video at higher resolutions.
Video Size
To save video, which is a representation of images or frames and sound in time, we must add the size of the images + the size of the sound.
Network Cards
Network cards are used to connect computers together to share resources (e.g., printers or files) and to form a network.
Local Area Networks (LAN)
Small networks with no communication with the outside are called local area networks or LAN (local area network). In this case, the network is established through a cable that connects all computers. The network card, therefore, allows a computer to communicate with a local network. They connect to an ISA or PCI slot on the motherboard, but many motherboards now have them integrated.
Modem Cards
The modem enables a computer to connect to other computers via a telephone line. The other computer can be an Internet service provider, a remote computer in another part of the world, a friend’s PC, a work computer, etc. Once connected, data can be transmitted in either direction, thus enabling you to download a web page, send messages, or share files.
The word modem comes from “modulation/demodulation” and its primary mission is to convert the digital data generated by the computer into analog signals to be sent via the telephone line. A second modem demodulates the analog signal back into digital data.
Types of Modems
Modems are of two basic types: internal and external. Current external modems connect via USB and internal ones to PCI or ISA slots on the motherboard.
Modem cards can be classified according to the type of network they provide access to. So we have three types:
- Typical modem card: This is what gives access to the basic telephone network. Allows speeds of 56 Kbps (kilobits per second).
- ISDN card: Provides access to Integrated Services Digital Network. Allows speeds of 144 and 192 kbps, for basic and primary access, respectively.
- ADSL card (ADSL stands for Asymmetric Digital Subscriber Line): Take advantage of the bandwidth of the basic telephone network to allow speeds of 256 Kbps to 20 Mbps (megabits per second).