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Data Storage
SIGN AND MAGNITUDE
Storing and representing numbers
Give the sign and magnitude of -30
Give the sign and magnitude of the following integers
+ 60 and -60+90 and -90+29 and -29
TWO’S COMPLEMENT REPRESENTATION
Represent -50 in two’s complement
Represent -38 in two’s complement
Perform the calculation 75 – 30, using two’s complement method.
Perform the calculation 90 – 30, using two’s complement method.
Perform the calculation 52– 27, using two’s complement method.
BINARY CODED DECIMAL(BCD)
Storing and representing digits and characters
Binary coded decimal (BCD) is a system of writing numerals that assigns a four-digit binary code to each digit 0 through 9 in a decimal (base-10) numeral.
Computer use the number system you have been studying in order to carry out calculations. Once a calculation is completed, the result has to be displayed in the decimal format on the screen, for example on electronic scoreboard, calculators, microwave ovens and digital clock.
BCD Representations
0000 – 00001 – 1 0010 – 2 0011 – 3 0100 – 4 0101 – 5 0110 – 6 0111 – 7 1000 – 8 1001 – 91101 – (-) negative sign1011 – (-)
Represent the digits 4901 in BCD form
Give the BCD representations of the following numbers:
91430256-81297
Covert BCD representation 010101111001 to decimal
Covert BCD representation 100000000101 to decimal
Covert the following BCD values into decimal
0010100100110000011101011001011110000000
Exam extract
ASCII
ASCII (American Standard Code for Information Interchange) is a character-encoding scheme. Originally based on the English alphabet, it encodes 128 specified characters into 7-bit binary integers.
Example
In a computer system using the seven bit ASCII representation, the letter J would be represented by 1001010 or 74, Give the ASCII representation of letters E and P.
Exercise 1
The ASCII representation of letter P has a decimal value of 80. What is the ASCII representation of letter S?
Exercise 2
Home Work
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