Theory Chapter 1 - Information Representation

Flashcards by TS P, updated more than 1 year ago
Created by TS P over 5 years ago


Advanced Level (A- Level) Computer Science (Information Representation) Flashcards on Theory Chapter 1 - Information Representation, created by TS P on 12/24/2015.

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Question Answer
How to convert from Binary to Denary? multiply the binary value with their place value and add it all up
How to convert from binary to hex? Divide into 4 bit digits/nibble (from the right), each nibble assign with a hex value, add extra 0s if needed
Convert denary to hex? Convert from decimal to binary , then from binary to hex
Convert hex to binary? Assign each hex value (from the right) with a nibble value. Repeat for all hex values, then group together.
hex to decimal? Put hex values into powers of 16 place values, multiply hex values by place values, and add them all together.
Convert a binary into its two's complement First turn every 1 in the binary string to a 0 and vice versa, this should give us the binary string’s one’s complement. Then add one to the newly converted string, this will result in 2’s complement
Hexadecimal's values? from 0-9 is 0-9 10 = A 11 = B 12 = C 13 = D 14 = E 15 = F
What problems do two's complement resolve? Two’s complement solves the double zero issue and the incorrect mathematics issue.
Convert from two's complement into decimal? Multiply the far left binary digit by its place value and then multiply by -1, then add this onto the denary value of the remainder bits. e.g. 100101 in 2’s complement is =(1x32x-1)+(0x16)+(0x8)+(1x4)+(0x2)+(1x1)= -27 in denary.
If a far bit left of a two's complement bit pattern is 1 ... ...the bit pattern represents a negative no.
What is ASCII, it's advantages and disadvantages? American Standard Code for Information Interchange, advantages: takes up little space since it's only storing 8 bits, disadvantages: 128 characters is not enough
What are Unicode? Character system ranging from UTF-8 to UTF-64, with over a million combinations. This, however, leads to more storage space required
What are BCDs? Binary Coded Decimals, taking every decimal digit and turning it into 4 bit pattern. E.g. 214 = 0010 0001 0100
Packed BCD vs Unpacked BCD Unpacked: 1 decimal digit = 1 byte Packed: 1 decimal digit = 1 nibble
Uses of BCD Due to its simple circuits, BCDs are used for simple maths calculations Useful for storing date and real-time values, like in the BIOS
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