Binary, headecimal signed 2s compliment Flashcards
Computer technology has all components that recognise only two states. What are they?
1 or 0 (binary aka on or off)
Binary code is used inside the computer to do what?
.store and manipulate data
What is a disadvantage of using binary code?
Difficult to document outside of the computer system
What can be used to document instead of binary code?
Hexadecimal representation
What type of system is binary?
Base 2
What type of system is hexadecimal?
Base 16
How is one hexadecimal symbol grouped?
in four bits (nibble)
Convert 1011 0110 0111 0001 into Denary
46705
Convert 485 into Binary - 16 bits
0000000111100101
Convert 865 into Hexadecimal
361
Convert 1011 0110 0111 0001 into Hexadecimal
B671
Convert AE2 into denary
2786
How many bits in a byte?
8 bits
Why do we need signed numbers?
To see if a binary number is positive or negative
How is a signed binary byte structured
The first bit is used to represent the + or - sign. 0 is positive and 1 is negative. The remaining bits total up the value. Another name for this is sign and magnitude.
Give a disadvantage of using sign and magnitude method
You have a positive and negative 0.
How do people normally store signed integers?
In 2’s complement
State what is meant by one’s complement
The binary number obtained by subtracting each digit in a binary number from 1
State what is meant by two’s complement
The one’s complement of a binary number plus 1
Express the number 10100100 in 2’s complement
01011100
How do you convert a negative denary number into binary Two’s
Complement
- Find the binary equivalent of the denary number
- Add an extra bit before the most significant bit and turn that into 0
- Flip all the bits: 0 to 1; 1 to 0
- Add 1
How do you Converting Two’s Complement to denary
- Flip all the bits: 0 to 1; 1 to 0
- Add 1
- Simple conversion from binary to denary
Give an example of where 2’s complement can be used
Digital displays. This is because you take the lowest negative value, and each successive higher value is obtained by adding 1 to the binary code. When all numbers in the nibble is 1, it rolls over again to all 0 - just like a digital display.
State what is meant by binary coded decimal?
Another method to grouping bits
Why use BCD?
If you need an application where single denary digits are required to be stored or transmitted - BCD is used
Give examples of BCD being used?
Calculator screen or digital time display or the display of currency on a computer
If a currency is $300.25, display this in BCD
0011 0000 0000 0010 1001
Add up 0.26 + 0.85 using BCD
0000 0001 0001 0001
State what is meant by ASCII
It is a coding scheme that allows text to be stored via a character code
State the columns of an ASCII table
Binary, Hexadecimal, Character, Description
How many different codes are available for 7 bit code.
27 (128)
What characters are contained in an ASCII table
Non-printing or control characters - there for data transmission or entering data in a computer terminal (not used much anymore).
Upper and Lower Case letters; Punctuation symbols; Numerals and Arithmetic Symbols
What is the problem with ASCII codes
Limited amount of characters can be stored not suitable for different languages.
State what can be used instead of ASCII code
Unicode - the first 128 characters is ASCII and has different lengths
How is Unicode structured
Uses a CODE POINT instead of character code (ASCII).
e.g.
U+0041 is the letter A where 0041 is hexadecimal.
Where Unicode uses ASCII (the first byte) it starts with 0.
