Computer Tower
The tower includes the physical components of the system that store and process data, including the power supply, processor and memory chips, and internal storage devices such as the hard drive. Input and output devices are connected to the computer tower through cables and connectors.
Monitor
The computer monitor is a device that is used to display visual output from the computer tower. It requires a separate power source and is connected to the tower by a cable.
Keyboard
The keyboard is covered with buttons called keys that you can use to type text and send commands to the computer through a USB cable.
Mouse
The mouse moves the onscreen cursor and lets you interact with elements displayed on the monitor screen. The mouse communicates with the computer tower either through wireless signals or through a USB cable.
Speakers
Speakers play audio output from the computer. Headphones are actually small speakers.
Software
Computer software encompasses all of the programs running on the system to perform specific computing tasks. Several different types of software must be present on a computer for it to work properly, including the operating system (such as Microsoft Windows) and applications (such as Microsoft PowerPoint and Google Chrome).
Binary
A system of Counting calculating from left to right
1
ON
2
OFF
Binary calculation
128 | 64 | 32 | 16 | 8 | 4 | 2 | 1
Bit
The smallest unit of digital information. Each individual one and zero in a binary sequence is a bit.
Byte
Eight bits together form a byte. The value of a single byte can range from 0 (eight 0s) to 255 (eight 1s). Because a single byte can't store much information, we usually talk about them in groups.
1 kilobyte
1024 bytes
1 megabyte
1024 kilobytes
1 gigabyte
1024 megabytes
1 terabyte
1024 gigabytes
Sample
Sound is caused by vibrating objects, which create pressure waves in the air. Digital sound recordings capture this continuous wave and divide it into discrete segments. Then, it assigns a value to each segment. A single segment's value is called its sample height.
Bit Depth
Recording programs have to decide how much memory they should allocate to store the value of each sample. The amount of memory used is called the bit depth. 8-bit sound uses eight bits (or one byte) to store the value of each sample. 16-bit sound uses two bytes per sample. Generally speaking, the better the bit depth, the better the sound.
Sampling Rate
Another setting that affects sound recording quality is the sampling rate, or how many individual samples are taken each second. This rate is measured in hertz (Hz). For example, a sampling rate of one thousand samples per second is the same as one thousand hertz, or one kilohertz (kHz). Most modern sound recordings are made at 44.1 kHz.
Frame Rate
Videos are made of a sequence of still images shown in rapid succession. Each individual image is called a frame. Frame rate is a measure of how many frames are shown each second. Most digital videos have a frame rate of about 30 frames per second.
Resolution
Resolution is a measure of how many pixels wide and tall each frame of a digital video is. The higher the resolution, the clearer the image will be.
Color Depth
Color depth is a measure of how much memory the computer uses to display colors. Eight-bit color images use one byte of data for each pixel, which means each pixel must be one of these 256 colors. 24-bit color, which uses three bytes for each pixel, can use millions of different colors.
RGB
Red Green Blue
RGB Display
Computer monitors are made up of tiny red, green, and blue lights. This is called an RGB display. Red, green, and blue are the three primary colors of light, and they can be combined to make all the colors of the visible spectrum. Each set of three lights is called a pixel. The image above uses three lights to represent a single pixel. When all three lights shine at the same time, our eyes perceive them together as white light. By combining two colors, you get the secondary colors of light. Red and green make yellow, red and blue make magenta, and green and blue make cyan. By varying the brightness of one or more of the lights, each pixel can display any color on the visible spectrum.
Raster Images
Raster (or bitmap) images are the most common kind of digital image. Computers store raster images by remembering the color of each pixel. For example, a yellow pixel might take three bytes to encode – one each for red, green, and blue. Since yellow is a combination of red and green, the computer might store the yellow pixel by using eight 1s for red, eight 1s for green, and eight 0s for blue. When the computer interprets this data, it turns the red and green lights all the way on, and the blue light all the way off.
Raster Image Pros
-They store each individual pixel so they can be very detailed.
-They are also easy to create.
-Most common so easy to share
Raster Image Cons
- They use tons of storage space.
- They have limits to how much you can scale the file.
- If you take a small image and make it larger, it’ll become pixelated.
Pixelated
Enlarging an image so far that the viewer sees the individual pixels that form the image.
Vector Images
Instead of storing each individual pixel, the computer stores points and curves. For example, to create a circle, a vector image may store four points, then tell the computer to connect the points with quarter arcs and fill the shape with a color.
Vector Image pros
- They’re scalable
- Generally take up less storage space than raster files
Vector Image Cons
- They’re difficult to create
- Require special software and training
- Usually lack the fine detail of raster images, which is why they’re usually used for images with only a few colors like logos and fonts
Lossless Compression
A compression algorithm that doesn't affect the original data. In other words, the uncompressed file will be exactly the same as the file before compression, bit for bit. Common lossless file types include:
.GIF .PNG .PDF .ZIP
Lossy Compression
A compression algorithm that slightly alters the data to make it easier to store. Lossy compression takes advantage of the limitations of human sight and hearing, and is usually used for images, videos, and audio files. Common lossy file types include:
.JPG .MP3 .MP4
Run-Length Encoding
A common lossless compression algorithm. Instead of storing each individual bit of a file, it stores how many of each bit appears in a sequence. For example, instead of storing thirty zeros in a row, it would just store the number thirty, followed by a zero. It can also store repeated patterns in data, such as identical pixels in an image.
Compression Artifact
Sometimes, when a video is compressed to a very small size, patches of pixels appear that have less visible detail than the rest of the image. These are called compression artifacts. They often appear in educational videos (such as the ones in this course) because file size is prioritized over video sharpness, which allows the videos to stream well on suboptimal hardware.
Confidentiality
Protecting confidential data and information
Human Dignity
Respecting the privacy and dignity of other human beings
Civility
Observing rules of "netiquette" that promote online civility
Property Rights
Refusing to violate the intellectual property rights of others
Ethics
Personal behaviors that build responsibility and trust. Computer ethics requires you to do more than simply avoid unlawful acts. It upholds ethical standards.