CPT4 Revision

CPT4 revision notes for AQA AS Computing.

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Version 3
CPT4: Binary and Binary Coded Decimal Revisited
Binary Representation:
The binary representation of 45 is:
128 64 32 16 8 4 2 1
0 0 1 0 1 1 0 1
Representation of a denary number to binary is done altogether by adding up to
create 45.
BCD (Binary Coded Decimal) Representation
The BCD representation of 45 is:
8 4 2 1 8 4 2 1
0 1 0 0 0 1 0 1
Representation in BCD is done by finding the binary code for each the `4' and
the `5'.
CPT4: Hex Numbers
The primary purpose of hex is to represent the binary code in a format easier for
humans to read and acts as a shorthand of binary.
Denary Value Hex Value
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 A
11 B
12 C
13 D
14 E
15 F
16 1
Method:
What is the Hex value of 45?
1. Find how many times 16 goes into 45 (45 div 16 = 2)
2. So the hex value for this is `2'
3. Find the value of the remainder (45 ­ (16*2) = 13)
4. So the hex value for 13 is `D'
5. The full Hex value is 2 D.
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Representation of Hex
In Books
In books, you can identify a hexadecimal as 5A3SIXTEEN or 5A3HEX.
In HTML
In HTML, you can identify hexadecimals as #FFFFFF where # identifies a
hexadecimal.
In C, C++, C#, Java and JavaScript
In these languages, a hexadecimal is shown with 0x. E.g.: 0x5A3.
In Ada and VHDL
In these languages, a hexadecimal is shown as 16#5a3#
Pascal
These languages use $ to show a hexadecimal.…read more

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2.360 = 2.36 x103
0.001025 = 1.025 x103
The exponential tells you how many places the point moves.
There are different parts of a floatingpoint number: the Mantissa, the base
number and the exponential, which is a whole number and indicates how many
places the binary point moves.…read more

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Step Two: As the exponential is positive, we move the binary point 3 places to
the right.
3 2 1 1/2 1/4 1/8 1/16 1/32
1 0 0 1 1 0 1 1
Step 3: The whole number represented is: 3
Step 4: The decimal is: 01325
Step 5: So the answer is: 3.…read more

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