CS Terms - Getting Started

Khan Academy AP CS Principles and Khan Academy Computing are good resources to learn and refresh some of this information.

Storage

• bit is 0 or 1, stands for “binary digit”
• byte is 8 bits, written for example like 1001 0101
• B - abbreviation for byte
• b - abbreviation for bit
• KB - kilobyte, 1000 bytes
• MB - megabyte, 1 million bytes
• GB - gigabyte, 1 billion bytes
• TB - terabyte, 1 trillion bytes

Base systems

• Able to convert between decimal, binary, hexadecimal, octal
• 15 = 1111 binary = F hex
• 255 = 1111 1111 binary = FF hex
• unsigned 8 bit integer ranges from 0 to 255
• signed 8 bit integer is between -128 and 127
• unsigned 32 bit integer ranges from 0 to 2³²-1, about 4 billion
• signed 32 bit integer ranges from -2³¹ to 2³¹-1, about +/-2 billion
• unsigned k bit integer at most 2^k-1

Computer components

• RAM - random access memory. The kind of memory used in computers, random access means any part of memory can be accessed without having to look at the rest of memory (same amount of time to look up any part of RAM).
• Hard drive / Hard disk - one of the two main long-term storage used in most computers. Physically, data is stored on magnetic platters that spin around very fast (spinning much like CD/DVD/record players)
• Solid state drive - the other main long-term storage used in most computers. Physically, data is normally stored in flash memory. SSDs are typically faster than HDDs but more expensive and have different error behavior.
• CPU - central processing unit - the part of the computer that is "in charge". Executes programs that are in "machine code".
• input devices - used to bring data into the computer - hard drive, keyboard, mouse, touch screen, modem
• output devices - computer sends data out to these - hard drive, screen, printer