Computer Systems and C++ Programming

• Outlines include: elements of a computer system, the language of a computer, the evolution of programming languages, a C++ program, processing a program, analysis-coding-execution cycle, and ANSI/ISO Standard C++.

Elements of a Computer System

• Includes hardware and software.
• Hardware consists of the Central Processing Unit (CPU), main memory, secondary storage, and input/output devices.

Central Processing Unit (CPU)

• The main components are the control unit (CU), arithmetic and logic unit (ALU), and registers.
• CU fetches and decodes instructions and is responsible for controlling the flow of information in and out of main memory, along with the operation of internal CPU components.
• ALU carries out all arithmetic and logical operations.
• Registers include the program counter (PC), which points to the next instruction to be executed, and the instruction register (IR), which holds the instruction currently being executed.

Main Memory

• Directly connected to the CPU.
• All programs must be loaded into main memory before the program can be executed.
• All data must be brought into main memory before it can be manipulated.
• All data in main memory is lost when computer power is turned off.

Secondary Storage

• Devices that store information permanently.
• Examples include hard disks, floppy disks, CD-ROMs, tapes, and flash drives.

Input/Output Devices

• Input devices feed data and programs into computers, including keyboards, mice, and secondary storage.
• Output devices display results, including monitors, printers, and secondary storage.

Software

• Programs that do specific tasks.
• System programs take control of the computer, like an operating system, that monitors the overall activity of the computer and provides services.
• Application programs perform a specific task, such as word processors, spreadsheets, and games.

Computer Language

• Digital signals are sequences of 0s and 1s, also known as machine code.
• Computers run machine language.
• A binary digit (bit) is the digit 0 or 1.
• A binary code is a sequence of binary digits.
• A byte is a sequence of eight bits.
• Kilobyte (KB) is 2^10 bytes, equivalent to 1,024 bytes.
• Megabyte (MB) is 1024 KB or 2^20 bytes, equivalent to 1,048,576 bytes.
• Gigabyte (GB) is 1024 MB or 2^30 bytes, equivalent to 1,073,741,824 bytes.
• Terabyte (TB) is 1024 GB or 2^40 bytes, equivalent to 1,099,511,627,776 bytes.

Programming Language Evolution

• Early computers were programmed in machine language.
• Assembly language instructions are mnemonic and easier to remember.
• Assembler: Translates a program written in assembly language into machine language.
• High-level languages simplify programming wages = rate * hours can be written in C++ as wages = rate * hours;
• Compiler: Translates a program written in a high-level language into machine language.

C++ Program Demonstration

• std::cout with insertion operator << inserts text into standard output.
• #include <iostream> is a preprocessor directive needed for input-output operations.
• using namespace std; declares that the program uses the standard namespace.
• int main() is the entry point of any C++ program.
• return 0; exits the main function.
• Statements can use a combination of constants, manipulators and functions
• New line is inserted into the output stream using endl;.
• cout << "My first C++ program." << endl; shows printing a literal string.
• cout << "The sum of 2 and 3 = " << 5 << endl; prints the sum of two numbers, represented by first a literal string and the sum integer.
• cout << “7 + 8 = " << 7 + 8 << endl; prints the result of adding literals representing numbers as a literal string and the result of the addition calculated.