CS 110 Lecture 1I) What is a Program?II) Basic Components of a Computer SystemIII) Evolution of programming?IV) The Java Development Environment:CS 110 Lecture 1This course has a dual purpose:A) The first objective of this course is to teach you the fundamental programming skills that you will need to successfully write programs. We will do this in the context of learning Java.B) The second objective is to teach you to write code that is robust, well structured, and maintainable and that adheres to sound principles of software engineering.I) What is a Program?A program is a set of step by step instructions that instructs the computer how to perform some task or accomplish some calculation. Programs contain “algorithms” which are setsof that explain exactly how to perform some calculation. One of the most difficult things that novice programmers need to understand is that each and EVERY detailed step of the task must be clearly defined, and that the computer can’t “remember” values unless we explicitly indicate that the value is to be “stored” in some memory location. {develop an algorithm to make a PB sandwich, and calculate the sum of the numbers from 1 to 10;}II) Basic Components of a Computer SystemThe various components a computer system all work together to contribute to the successful execution of a program. When a program is executed, the steps or statements inside the program are processed one at a time frequently in the order that they occur inside the program file.Input Devices: Input devices provide data to a program in execution, and include keyboards, mice, light pens etc… As a program executes frequently it will require additional information to perform calculations, and this category of devices allow users tocommunicate with the program, and to provide data during execution. Output: Output devices allow the program to display information to the user, while executing. These devices include printers, and displays. Secondary Storage: Data entered through input devices, displayed on screens, or stored in memory as the program executes is volatile. Storage devices such as disks and CD’s provide a means for the long term retention of data, and files containing program code. The main components involved in the execution of a program are Memory and the CPUMemory: Before a program can be executed, it must be loaded from disk into memory. Volatile main memory is used for the temporary storage of programs and their associated data while executing. It consists of a series of locations, into which “executable program code”, and data can be loaded. Each memory location or “cell” has an address.When a program is executed, it is loaded from disk into memory in a series of CONSECUTIVE (adjacent) locations. The first instruction in the program has the “lowest” address. During execution, instructions are copied from memory into the computer’s CPU which is responsible for decoding and executing the instruction.It is important to note, that in memory everything is stored as a series of 1’s and 0’s which is known as Binary. Each bit (or binary digit) represents the presence or absence of an electrical pulse (high and low voltage). Bits individually are not very useful, usually the smallest addressable unit in a computers memory is a byte, which consists of 8 bits. A byte is sufficient to store the representation of a character in the ASCII character set. For example 1000001 is an “A”. Other encoding schemes exist, for instance Java and many new languages use a different character representation called UNICODE which represents characters using 16 bits, the If we are dealing with only the English language, the first 128 characters of Unicode are the same as the characters in ASCII. The advantage of UNICODE is that it allows for the representation of characters of most modern alphabets. In Unicode 0000000010000001 is “A”. To represent more complex values bytes are grouped together into words. The exact number of bits in word varies from one family of architectures to another… Frequently it is 4.When we write a program statement in some language, print (“Hello World”); , it can not be directly executed by the computer, before it can be executed, a program must be translated into the “native” language of the machine, 1’s and 0’s, known machine code or machine language. (The executable version of a program is in machine language) Each machine language statement performs one SIMPLE operation, such as retrieving data from some memory location. Machine language is specific to a particular architecture, sowhen we move a program from one kind of machine to another, we would need translate it again.Cpu: The Central Processing Unit is responsible for executing instructions and is essentially the brain of the computer. The speed of the CPU determines how many machine instructions per second it can execute. It consists of a set of specialized registerswhich perform various functions:Control Unit: this component is responsible for fetching and decoding the next instruction from memory, controlling the flow of instructions and data between the CPU and memory, and controlling the operation of the CPU’s other components.Data Registers are used to contain the data associated with instructions while they are being executed. the instruction register that contains the “current” instruction, and the program counter which contains the address of the next instruction.Instruction Register: Holds the current machine instruction being executed.Program counter: contains the address of the next instruction to execute.Instructions are transferred from memory into the CPU during the fetch execute cycle. At the beginning of each cycle, the “next” instruction fetched from memory and stored in the instruction register, decoded, and executed. The number of instructions that executed is determined by the clock rate of the computer. :III) Evolution of programming?The evolution of programming and programming languages is closely tied to the advancements made in computing hardware. In the early days of computing, programming/computing was difficult and limited in availability.- 1948 – 64 => Main frames, Custom Software written “in house”, by Data processing professionals. Programs were “relatively” simple single purpose systems. Operating systems if they existed at all….were generally single usero