C AND C++
- C++ is an extension of C originally created by Bjarne Stroustrup with additional features like object-based programming, object-oriented programming, and generic programming.

- C is a general purpose programming language that was originally designed by Dennis Ritchie of Bell Laboratories. It was first used as the systems language for the UNIX operating system. Ken Thompson, the developer of UNIX, had been using both assembler and a language named B to produce initial versions of UNIX in 1970. C was invented to overcome the limitations of B. B was a programming language based on BCPL, a language developed by Martin Richards in 1967 as a typeless programming language. Its basic data type was the machine word, and it made heavy use of pointers and address arithmetic.

COMPUTER
- A computer is a device capable of performing computations and making logical decisions many times faster than we could.

COMPUTER PROGRAMS
- Computer Programs are set of instructions that control how computers process data.These instructions guide the computer through orderly set of actions.

HARDWARE
- The various devices such as the keyboard, screen, "mouse", disks, memory, CD-ROM and processing units that comprise a computer system are called the hardware.

SOFTWARE
- The computer programs that run on a computer are called as the software.

SOFTWARE DEVELOPMENT METHODS
Structured Programming,
Top-down stepwise refinement,
Functionalization, and
Object-oriented Programming.

COMPUTER ORGANIZATION
- SIX LOGICAL UNITS

INPUT UNIT
Receiving section of the computer. It obtains information i.e., data and computer programs from various input devices and places this information at the disposal of the other units.

OUTPUT UNIT
Shipping section of the computer. It takes information that has been processed by the computer and places it on various output devices to make the information available for use outside the computer.

MEMORY UNIT
Warehouse section of the computer. It retains information that has been entered through the input unit so that the information may be made immediately available for processing when it is needed. It also retains processed information until that information can be placed on output devices by the output unit.

ALU
Arithmetic Logic Unit. Manufacturing section of the computer. It is responsible for performing calculations such as addition, subtraction, multiplication, and division. It contains the decision mechanisms that allow the computer to compare two items from the memory unit to determine whether or not they are equal.

CPU
Central Processing Unit. Administrative section of the computer. It is the computer's coordinator and is responsible for supervising the operation of the other sections. The CPU tells the input unit when information should be read into the memory unit, tells the ALU when information from the memory unit should be utilized in calculations, and tells the output unit when to send information from the memory unit to certain output devices.

SECONDARY STORAGE UNIT
Long-term ware house section of the computer. Programs or data not actively being used by the other units are normally placed on secondary storage devices such as disks until they are again needed later.

OPERATING SYSTEMS
In single user batch processing, the computer runs a single program at a time while processing data in groups or batches.

Operating systems are software systems that make it more convenient to use computers and to get the best performance from your computers.

Multiprogramming operating systems enable the simultaneous operation of many jobs on the computer- the computer shares its resources among the jobs.

Time sharing is a special case of multiprogramming in which users access the computer through terminals. The user's programs appear to be running simultaneously.

With distributed computing, an organization's computing is distributed via networking to the sites where the real work of the organization is performed.

Servers store programs and data that may be shared by client computers distributed throughout a network, hence the term client/server computing.

LANGUAGES

MACHINE LANGUAGE -

Cumbersome for humans, example:

The following section of a machine language program adds overtime pay to base pay and stores the result in gross pay:

+1300042774
+1400593419
+1200274027

ASSEMBLY LANGUAGE -

Little better, example:

The following section of an assembly language does the same job as above machine language:

LOAD - BASEPAY
ADD - OVERPAY
STORE - GROSSPAY

The assembly language needs a translator program called the ASSEMBLER to convert it to machine language which is the only language the computer directly understands.

HIGH-LEVEL LANGUAGE -
Many languages that look like English, example:
The above program might look like

grossPay = basePay + overTimepay

Translator programs called COMPILERS convert high-level language programs to machine language.