SMK Lundu ICT Class: State the relationship of data representation: bit, byte and character
A bit is the smallest individual piece of data. For most computers, that is a binary value of 0 or 1, represented by a lack or presence of voltage respectively. Packing multiple characters into a single larger-thanbit-byte is possible but not particularly efficient, and it's been . Byte: 8 bits, lets you encode different states. Learn why bits are the basic building block of all computer data and learn about why these are represented in binary with GCSE Computer Science. One extended-ASCII character in a text file (eg 'A'), 1 byte. The word 'Monday' in a. Eight bits that are grouped together as a unit. A byte provides enough different combinations of 0s and 1s to represent individual characters.
To find the code for a particular character in the table, add its row number on the left 32, 48, etc. A more comprehensive ASCII table is the following, which includes control characters with their associated graphic symbols, and, for each character, its hexadecimal, decimal and binary codes: Click for bigger image. The 8 bits are depicted in groups of four, because four bits are used to represent a single digit in the hexadecimal system, that we will discuss later.
The first two rows of the table represent so-called control characters, characters that are not visible, such as backspace BSescape ESCCR carriage return - an old word for enteretc.
If you are interested in all acronyms, the AsciiTable website explains them in detail. Yes, even the space character needs to be represented. The actual ASCII system starts at 0, but the first 32 characters are "control" characters, because they were originally used to control the early printers.
Since those characters are not interesting in the context of this class, we've omitted them from the table. Line Endings If all we had to worry about was characters, text representation would be pretty straightforward. In the olden days before Windows, Macs and Unix, the early teletype printers used two control characters at the end of each line: The Mac represents the end of a line with a carriage return character.
Digital devices almost always use two values binary for similar reasons: Using ten digits like we do in our every day decimal counting system would obviously be too challenging. After all, you could do all the same things with a 10 digit system? As it happens, people have tried to build decimal-based computers, but it's just too hard. Recording a digit between 0 and 9 involves having accurate equipment for reading voltage levels, magnetisation or reflections, and it's a lot easier just to check if it's mainly one way or the other.
There's a more in-depth discussion on why we use binary here: Watch the video online at https: Numbers In this section, we will look at how computers represent numbers.
To begin with, we'll revise how the base number system that we use every day works, and then look at binary, which is base After that, we'll look at some other charactertistics of numbers that computers must deal with, such as negative numbers and numbers with decimal points.
Understanding the base 10 number system The number system that humans normally use is in base 10 also known as decimal. It's worth revising quickly, because binary numbers use the same ideas as decimal numbers, just with fewer digits! In decimal, the value of each digit in a number depends on its place in the number.
Each place value in a number is worth 10 times more than the place value to its right, i. Also, there are 10 different digits 0,1,2,3,4,5,6,7,8,9 that can be at each of those place values.
If you were only able to use one digit to represent a number, then the largest number would be 9. After that, you need a second digit, which goes to the left, giving you the next ten numbers 10, 11, It's because we have 10 digits that each one is worth 10 times as much as the one to its right. For example, if you want to write the number in expanded form you might have written it as: The key ideas to notice from this are: Decimal has 10 digits -- 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
A place is the place in the number that a digit is, i. For example, in the number3 is in the "hundreds" place, 2 is in the "tens" place, and 9 is in the "ten thousands" place. Numbers are made with a sequence of digits. The right-most digit is the one that's worth the least in the "ones" place. The left-most digit is the one that's worth the most. Because we have 10 digits, the digit at each place is worth 10 times as much as the one immediately to the right of it.
All this probably sounds really obvious, but it is worth thinking about consciously, because binary numbers have the same properties.
ARCHIVED: What are bits, bytes, and other units of measure for digital information?
Representing whole numbers in Binary As discussed earlier, computers can only store information using bits, which only have 2 possible states. This means that they cannot represent base 10 numbers using digits 0 to 9, the way we write down numbers in decimal. Instead, they must represent numbers using just 2 digits -- 0 and 1. Binary works in a very similar way to Decimal, even though it might not initially seem that way. Because there are only 2 digits, this means that each digit is 2 times the value of the one immediately to the right.
The word "denary" also refers to the Roman denarius coin, which was worth ten asses an "as" was a copper or bronze coin. The interactive below illustrates how this binary number system represents numbers. Have a play around with it to see what patterns you can see. Click to load Binary Number Calculator Use the interactive online at http: Find the representations of 4, 7, 12, and 57 using the interactive.
What is the largest number you can make with the interactive? What is the smallest? Are there any numbers with more than one representation? This is exactly the same as decimal! When set to 0, a bit does not add anything to the total. So the idea is to make numbers by adding some or all of 32, 16, 8, 4, 2, and 1 together, and each of those numbers can only be included once.
Image source Choose a number less than 61 perhaps your house number, your age, a friend's age, or the day of the month you were born onset all the binary digits to zero, and then start with the left-most digit 32trying out if it should be zero or one. See if you can find a method for converting the number without too much trial and error.
Try different numbers until you find a quick way of doing this. A word consists of the number of data bits transmitted in parallel from or to memory in one memory cycle. Word size is thus defined as a structural property of the memory.
Block refers to the number of words transmitted to or from an input-output unit in response to a single input-output instruction. Block size is a structural property of an input-output unit; it may have been fixed by the design or left to be varied by the program. Archived PDF from the original on Figure 2 shows the Shift Matrix to be used to convert a bit wordcoming from Memory in parallel, into charactersor 'bytes' as we have called them, to be sent to the Adder serially.
The 60 bits are dumped into magnetic cores on six different levels. Thus, if a 1 comes out of position 9, it appears in all six cores underneath. Pulsing any diagonal line will send the six bits stored along that line to the Adder.
The Adder may accept all or only some of the bits.