Computer Science - Representing data in a computer + databases 📀 Flashcards
How is data stored?
Data is stored in each memory location in a pattern of bits.
Bit patterns can represent different types of data such as…
Bit patterns can represent different types of data such as numbers, text, audio, images, graphics, and video.
Computers store and manipulate data in the form of…
Computers store and manipulate data in the form of electronic pulses.
What are the 2 signal states that a computer represents data with?
ON (The high voltage level) OFF (The low voltage level)
How is the digitized data represented numerically?
It is represented using the binary number system (base 2) which only uses 1s and 0s.
Since there are only 2 states in a computer, it is called a _______.
Since there are only 2 states in a computer, it is called a bi-stable device.
How does you pressing a letter lead to it being shown on the screen?
Electrical signals are sent from the keyboard to the CPU. The CPU turns the signals into binary code. Then, the computer reads the code and sends it to the monitor to display the letter.
A bit is a ____.
A bit is a single digit in a binary number; it is either a 0 or a 1. It is the smallest unit of memory the computer stores.
What is a byte?
A byte is a group of 8 bits, representing a single character. It is normally the smallest grouping used by computers.
8 bits =
1 byte
1024 bytes =
1 kibibyte
1024 kibibytes =
1 mebibyte
1024 mebibytes =
1 gibibyte
1024 gibibytes =
1 tebibytes
What are the three most common number systems?
Decimal (denary), Binary, and Hexadecimal.
What is the base of the decimal number system?
10
What is the base of the hexadecimal number system?
16
Since the base of the hexadecimal number system is 16, what are the characters used to represent the final 5 digits?
A (10), B (11), C (12), D (13), E (14), F (15).
How do you convert a decimal (denary) number to its binary equivalent?
1) Write down the decimal number.
2) Continually divide by 2 to give a remainder of 1 or 0
3) Keep doing this till the final result is 1 or 0
4) You can get the binary result by putting the binary numbers together, starting from the bottom. If the result is not a byte, fill in the spaces before the answer with zeros.
Recommended to see the method in book as it is hard to visualise.
How do you convert a binary number to its decimal/ denary equivalent?
I can’t explain the method in writing and cannot put images in the answers without a pro subscription but uhh here’s a link to a picture of the method, keep it open in a new tab and open it whenever you get this flashcard… https://i.pinimg.com/originals/68/57/33/68573306c2979a81384b814e53adbaa2.gif
What is a database?
A database is a store of data that has been organised in some way.
Why are databases useful?
Databases are so useful because they store data in a structured way. When data is structured, it can be manipulated easily and then output in different ways.
Databases consist of:
1) Files/tables
2) Records
3) Fields
What is a file/table?
A collection of records and fields is called a file.
What is a record?
One single row of a database represents one record.
What is a field?
Each cell of a table indicates a single field. A single field can hold one piece of data.
What is a key field?
A key field is an individual piece of data that is unique.. A key field is used to differentiate one record from another.
