In integer representation, we learn how to represent signed integers using a fixed number of bits.
This chapter focuses on understanding the fundamentals of integer representation, including the
concepts of signed and unsigned integers, two's complement representation, and arithmetic
operations.
Signed and Unsigned Integers
In computing, we represent integers using a fixed number of bits. We can represent two types of
integers: signed and unsigned. An unsigned integer can only represent positive numbers and zero,
while a signed integer can represent both positive and negative numbers, including zero.
For example, if we have an 8-bit unsigned integer, it can represent numbers from 0 to 255. However,
if we have an 8-bit signed integer, it can represent numbers from -128 to 127.
Two's Complement Representation
Two's complement representation is a way of representing signed integers using a fixed number of
bits. It uses the most significant bit (MSB) as a sign bit, where 0 represents positive and 1 represents
negative. The remaining bits represent the magnitude of the number.
To convert a positive number to two's complement representation, we simply represent it as is.
However, to convert a negative number to two's complement representation, we first find the binary
complement of its magnitude and then add 1 to it.
For example, to convert the decimal number -5 to 8-bit two's complement representation, we first
find the binary complement of its magnitude (5 in binary is 0101, so its complement is 1010). Then,
we add 1 to it, resulting in 1011. Therefore, -5 in 8-bit two's complement representation is 1011.
Arithmetic Operations
Arithmetic operations on signed integers can be performed using two's complement representation.
Addition and subtraction can be done using basic binary addition and subtraction, while
multiplication and division can be done using algorithms that take into account the sign of the
numbers.
For example, to add -5 and 3 in 8-bit two's complement representation, we first convert 3 to 8-bit
two's complement representation (00000011). Then, we perform binary addition on the two
numbers:
1011 (−5)
+ 00000011 (+3)
-----------
1011010 (−2)
Therefore, -5 + 3 = -2 in 8-bit two's complement representation.
In conclusion, integer representation is a fundamental concept in computing that allows us to
represent and perform arithmetic operations on signed and unsigned integers. Understanding two's
complement representation and its arithmetic operations is essential for programming and computer
architecture.
, properties of integer representations
In this chapter, we delve into the properties of integer representations, with a particular focus on
unsigned and two's complement representations.
Unsigned integer representation is a simple and straightforward way to represent non-negative
integers. As the name suggests, there are no negative numbers in this representation, only positive
numbers and zero. In this representation, the integer value is determined by the bits set to 1, where
each bit represents a power of 2. For example, the decimal number 13 can be represented in binary
as 1101, which would be interpreted as (12^3) + (12^2) + (02^1) + (12^0) = 8 + 4 + 0 + 1 = 13.
Two's complement representation, on the other hand, allows for the representation of both negative
and non-negative integers. This representation uses a fixed number of bits and assigns a specific
pattern of bits to negative numbers. The leftmost bit, known as the sign bit, indicates whether a
number is positive or negative. If the sign bit is 0, then the number is positive, and the remaining bits
are interpreted as in unsigned integer representation. If the sign bit is 1, then the number is negative,
and the remaining bits are complemented and 1 is added to the result.
Let's consider an example to illustrate this. Suppose we have a 4-bit two's complement
representation. To represent the decimal number -3, we complement the bits for the positive
representation of 3, which is 0011, to get 1100. Then, we add 1 to get 1101, which is the two's
complement representation of -3.
In both unsigned and two's complement representation, there are certain properties that are
important to understand. One such property is that when incrementing the maximum positive
number, it rolls over to the minimum negative number. This is known as overflow. For example, in an
8-bit unsigned integer representation, if we increment 255 (which is represented as 1111 1111 in
binary), we get 0 (represented as 0000 0000 in binary). Similarly, in a 4-bit two's complement
representation, if we increment -1 (which is represented as 1111 in binary), we get -2 (represented
as 1110 in binary).
Another important property is that when decrementing the minimum negative number, it rolls over
to the maximum positive number. This is also known as underflow. For example, in a 4-bit two's
complement representation, if we decrement -8 (which is represented as 1000 in binary), we get 7
(represented as 0111 in binary).
Understanding these properties of integer representations is crucial when working with computer
systems and programming languages that use fixed-size integers, as they can lead to unexpected
results and errors if not properly handled.
Signed Integer Representation Methods
Sure, I'll do my best to provide a human-level, pro fluent summary of the chapter on Signed Integer
Representation Methods. I'll focus on one method in particular, the two's complement method, which is the
most commonly used method in modern computers.
Two's Complement Method
The two's complement method represents negative numbers in a way that makes arithmetic simpler. It is based
on the principle that a negative number can be represented as the complement of its positive equivalent.