1. Understand Computer Storage and Data Types
LESSON 1.1
Software Development Fundamentals
Understand Computer Storage and Data Types

2. Lesson Overview
Students will understand computer storage and data types.
In this lesson, you will learn:
How a computer stores programs and instructions in computer memory
Memory stacks and heaps
Memory size requirements for the various data storage types
Numeric data and textual data

3. Guiding Questions How are program instructions stored in a computer?
Identify the different data types that can be used and the values they can hold.
Use the guiding questions as a class starter, allowing the students time to answer the questions in their journals. Discuss student answers to the questions.
Primary and secondary storage. Stacks or heaps depending on the type of data.
int–integers, float, double; decimal–decimal values; bool–Boolean values (true/false), etc.

4. Activator Name the components of a computer.
What components are involved in storing program instructions?
CPU, RAM, hard drive, monitor, etc.
RAM and hard drive

5. Review Terms
Data type—a definition of a set of data that specifies the possible range of values of the set, the operations that can be performed on the values, and the way in which the values are stored in memory.
Garbage collection—a process for automatic recovery of heap memory.
Heap—a portion of memory reserved for a program to use for the temporary storage of data structures whose existence or size cannot be determined until the program is running.
Memory —a device where information can be stored and retrieved.
Stack—a region of reserved memory in which programs store status data such as procedure and function call addresses, passed parameters, and sometimes local variables.

6. How a computer stores programs in memory
A computer keeps data and programs in storage as follows:
Primary storage—Otherwise known as random access memory (RAM), it is made of memory chips. In common usage, it refers only to a computer’s main memory, the fast semiconductor storage (RAM) directly connected to the processor.
Secondary storage—Otherwise known as a hard drive, it consists of a read/write head that floats above rotating platters coated with a magnetic material.

7. Memory–Stacks and Heaps
Variables are stored in either a stack or heap based on their type:
Value types (e.g.: int, double, float) go on the stack.
Reference types (String, Object) go on the heap.
* Value types in classes are stored with the instance of the class on the heap.
The stack
Values in the stack are managed without garbage collection because items are added and removed from the stack as last in, first out (LIFO) every time you enter or exit a scope, like a method or statement
A StackOverFlowException occurs because you have used up all the available space in the stack.

8. Memory–Stacks and Heaps (continued)
The heap
A heap-based memory allocation occurs when we create a new object, at which point the compiler figures out how much memory is needed and allocates an appropriate amount of memory space and returns a reference representing the memory address.
A heap is used for dynamic allocation of memory.
The Microsoft® .NET Framework uses garbage collection to free up space during run time.
Garbage collection is an automatic process for recovery of heap memory. Blocks of memory that had been allocated but are no longer in use are freed, and blocks of memory still in use may be moved to consolidate the free memory into larger blocks.

9. Data Types Numeric data types Integral types (e.g.: byte, char, int)
Floating-point types (float, double)
Decimal
Boolean
Example: bool done = false;

10. Data Types Numeric data types Integral types (e.g.: byte, char, int)
Floating-point types (float, double)
Decimal
Boolean
bool done = false;

11. Integral Types Type Range Size sbyte -128 to 127 Signed 8-bit integer
Unsigned 8-bit integer
char
U+0000 to U+ffff
Unicode 16-bit character
short
-32,768 to 32,767
Signed 16-bit integer
ushort
0 to 65,535
Unsigned 16-bit integer
int
-2,147,483,648 to 2,147,483,647
Signed 32-bit integer
uint
0 to 4,294,967,295
Unsigned 32-bit integer
long
-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
Signed 64-bit integer
ulong
0 to 18,446,744,073,709,551,615
Unsigned 64-bit integer
The ranges seen here are for the .NET Framework

12. Floating-Point Types Type Approximate Range Precision float
±1.5e−45 to ±3.4e38
7 digits
double
±5.0e−324 to ±1.7e308
15-16 digits
The ranges seen here are for the .NET Framework.

13. Decimal Type Type Approximate Range Precision decimal
±1.0 × 10−28 to ±7.9 × 1028
28-29 significant digits
The ranges seen here are for the .NET Framework.

14. Using the Numeric Data Types
byte numKids = 15;
char letter = ‘p’;
int worldPopulation = ;
float money = f;
double lotsaMoney = 2.4E+12;
decimal testGrade = 89.5m;

15. Lesson Review
Describe how the program statement below is stored in memory:
int tennisPoints = 30;
Identify the appropriate data types for each of the following values.
100
-2323
true
This is the last slide of the presentation.