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Register Memory
Register memory is the smallest and fastest memory in a computer. It is not a part of the main memory and is located in the CPU in the form of registers, which are the smallest data holding elements. A register temporarily holds frequently used data, instructions, and memory address that are to be used by CPU. They hold instructions that are currently processed by the CPU. All data is required to pass through registers before it can be processed. So, they are used by CPU to process the data entered by the users.

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Registers hold a small amount of data around 32 bits to 64 bits. The speed of a CPU depends on the number and size (no. of bits) of registers that are built into the CPU. Registers can be of different types based on their uses. Some of the widely used Registers include Accumulator or AC, Data Register or DR, the Address Register or AR, Program Counter (PC), I/O Address Register, and more.

Types and Functions of Computer Registers:
Data Register: It is a 16-bit register, which is used to store operands (variables) to be operated by the processor. It temporarily stores data, which is being transmitted to or received from a peripheral device.
Program Counter (PC): It holds the address of the memory location of the next instruction, which is to be fetched after the current instruction is completed. So, it is used to maintain the path of ex*****on of the different programs and thus executes the programs one by one, when the previous instruction gets completed.
Instructor Register: It is a 16-bit register. It stores the instruction which is fetched from the main memory. So, it is used to hold instruction codes, which are to be executed. The Control Unit takes instruction from Instructor Register, then decodes and executes it.
Accumulator Register: It is a 16-bit register, which is used to store the results produced by the system. For example, the results generated by CPU after the processing are stored in the AC register.
Address Register: It is a 12-bit register that stores the address of a memory location where instructions or data is stored in the memory.
I/O Address Register: Its job is to specify the address of a particular I/O device.
I/O Buffer Register: Its job is to exchange the data between an I/O module and the CPU.

Register Memory
Register memory is the smallest and fastest memory in a computer. It is not a part of the main memory and is located in the CPU in the form of registers, which are the smallest data holding elements. A register temporarily holds frequently used data, instructions, and memory address that are to be used by CPU. They hold instructions that are currently processed by the CPU. All data is required to pass through registers before it can be processed. So, they are used by CPU to process the data entered by the users.

Computer Memory
The computer memory holds the data and instructions needed to process raw data and produce output. The computer memory is divided into large number of small parts known as cells. Each cell has a unique address which varies from 0 to memory size minus one.

Computer memory is of two types: Volatile (RAM) and Non-volatile (ROM). The secondary memory (hard disk) is referred as storage not memory.

But, if we categorize memory on behalf of space or location, it is of four types:

Hard Real-Time Systems:

These are used for the applications where timing is critical or response time is a major factor; even a delay of a fraction of the second can result in a disaster. For example, airbags and automatic parachutes that open instantly in case of an accident. Besides this, these systems lack virtual memory.

Soft Real-Time Systems:

These are used for application where timing or response time is less critical. Here, the failure to meet the deadline may result in a degraded performance instead of a disaster. For example, video surveillance (cctv), video player, virtual reality, etc. Here, the deadlines are not critical for every task every time.

Advantages of real-time operating system:

The output is more and quick owing to the maximum utilization of devices and system
Task shifting is very quick, e.g., 3 microseconds, due to which it seems that several tasks are executed simultaneously
Gives more importance to the currently running applications than the queued application
It can be used in embedded systems like in transport and others.
It is free of errors.
Memory is allocated appropriately.
Disadvantages of real-time operating system:

A fewer number of tasks can run simultaneously to avoid errors.
It is not easy for a designer to write complex and difficult algorithms or proficient programs required to get the desired output.
Specific drivers and interrupt signals are required to respond to interrupts quickly.
It may be very expensive due to the involvement of the resources required to work.

Real Time operating System
A real-time system is defined as a data processing system in which the time interval required to process and respond to inputs is so small that it controls the environment. The time taken by the system to respond to an input and display of required updated information is termed as the response time. So in this method, the response time is very less as compared to online processing.

Real-time systems are used when there are rigid time requirements on the operation of a processor or the flow of data and real-time systems can be used as a control device in a dedicated application. A real-time operating system must have well-defined, fixed time constraints, otherwise the system will fail. For example, Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc.

The interaction between a user and the computer does not occur in this system. The user is required to prepare jobs on punch cards in the form of batches and submit them to the computer operator. The computer operator sorts the jobs or programs and keeps similar programs or jobs in the same batch and run as a group to speed up processing. It is designed to execute one job at a time. Jobs are processed on a first-come, first-serve basis, i.e., in the order of their submission without any human intervention.

For example, the credit card bill generated by banks is an example of batch processing. A separate bill is not generated for each credit card purchase, rather a single bill that includes all purchases in a month is generated through batch processing. The bill details are collected and held as a batch, and then it is processed to generate the bill at the end of the billing cycle. Similarly, in a payroll system, the salaries of employees of the company are calculated and generated through the batch processing system at the end of each month.

Advantages of Batch processing operating system:

Repeated jobs can be completed easily without any human intervention
Hardware or system support is not required to input data in batch systems
It can work offline, so it causes less stress on the processor as it knows which task to process next and how long the task will last.
It can be shared among multiple users.
You can set the timing of batch jobs so that when the computer is not busy, it can start processing the batch jobs such as at night or any other free time.
Disadvantages of batch processing operating systems:

we need to train the computer operators for using the batch system.
It is not easy to debug this system.
If any error occurs in one job, the other jobs may have to wait for an uncertain time.

Types of Operating System:
1) Batch Processing Operating System:
2) Time Sharing Operating System:
3) Distributed Operating System:
4)Network Operating System:
5) Real-Time Operating System:

Major Functions of Operating System:

Memory management: - It manages both the primary and secondary memory such as RAM, ROM, hard disk, pen drive, etc. It checks and decides the allocations and deallocation of memory space to different processes. When a user interacts with a system, the CPU is supposed to read or write operations, in this case, OS decides the amount of memory to be allocated for loading the program instructions and data into RAM. After this program is terminated, the memory area is again free and is ready to be allocated to other programs by the OS.

Processor Management: - It facilitates processor management, where it decides the order for the processes to access the processor as well as decides the processing time to be allocated for each process. Besides this, it monitors the status of processes, frees the processor when a process is executed then allocates it to a new process.

Device/ hardware management: The operating system also contains drivers to manage devices. A driver is a type of translation software that allows the operating system to communicate with devices, and there are different drivers for different devices as each device speaks a different language.

Run software applications: - It offers the environment to run or use software applications developed to perform specific tasks, for example, Ms Word, Ms Excel, Photoshop, etc.
Data management: It helps in data management by offering and displaying directories for data management. You can view and manipulate files, folders, e.g., you can move, copy, name, or rename, delete a file or a folder.

Evaluates the system's health:- It gives us an idea about the performance of the hardware of the system. For example, you can see how busy the CPU is, how fast the data is retrieved from the hard disk, etc.

Provides user interface: - It acts as an interface between the user and the hardware. It can be a GUI where you can see and click elements on the screen to perform various tasks. It enables you to communicate with the computer even without knowing the computer's language.

I/O management: - It manages the input output devices and makes the I/O process smooth and effective. For example, it receives the input provided by the user through an input device and stores it in the main memory. Then it directs the CPU to process this input and accordingly provides the output through an output device such as a monitor.

Security: - It has a security module to protect the data or information stored in the memories of the computer against malware and unauthorized access. Thus, it not only manages your data but also helps to protect it.

Time Management: - It helps CPU in time management. The Kernel OS keeps checking the frequency of processes that requests CPU time. When two or more processes that are equally important compete for the CPU time, then the CPU time is sliced into segments and allocated to these processes in a round-robin fashion to prevent a single process from monopolizing the CPU.

Deadlock Prevention: - Sometimes a resource that is supposed to be shared by two or more processes is held by one process due to which the resource cannot continue. This situation is known as deadlock. The OS does not let this situation arise by carefully distributing the resources among the different processes.

Interrupt Handling: - also responds to interrupts, which are signals generated by a program or a device to seek the attention of the CPU. The OS checks the priority of the interrupt, and if it is more important than the currently running process, it stops the ex*****on of the current process and preserves this state of CPU then executes the requested process. Thereafter the CPU returns to the same state where it was stopped.

An operating system is a type of software without which you cannot operate or run a computer. It acts as an intermediary or translation system between computer hardware and application programs installed on the computer. In other words, you cannot directly use computer programs with computer hardware without having a medium to establish a connection between them.

Besides this, it is also an intermediary between the computer user and the computer hardware as it provides a standard user interface that you see on your computer screen after you switch on your computer. For example, the Windows and the Mac OS are also operating systems that provide a graphical interface with icons and pictures to enable users to access multiple files and applications simultaneously.

So, although the operating system is itself a program or software, it allows users to run other programs or applications on the system. We can say that is works behind the scenes to run your computer.

Now We Start Second Unit.
OPEARTING SYSTEM.

Computer Languages
The computer languages are those languages by which the user can communicate with the machine. There are various types of programming languages via we can write the programs. The program is the set of instructions which has to be executed by the computer.

Every language has its strengths and weaknesses, which are used by us. The programming languages are used for the implementation of different algorithms. These have a various purpose which are given below:

Any individual has to instruct the computer system, for everything he wants to do in the human-readable form.
The programmer or coder can structure the instructions into functions, procedures, etc. These procedures allow the program to break into “chunks,” and it makes the program easy to read.
The programming language provides portability.
The computer can understand binary language only, which is in the form of 0’s and 1’s, it is also known as machine language. The binary language is challenging to learn and understand for the fresher.

Computer programming consists of a full understanding of how and why the computer systems, and we can set realistic expectations. There are three types of computer languages:

1) Low-Level Language
2) Middle-Level Language
3) High-Level Language

The period of the fifth generation is 1980-onwards. The VLSI technology develops into ULSI (ultra large scale integration) technology in the fifth generation. These are used in the production of microprocessor chips which have ten million electronic components.

The fifth-generation computers are based on parallel processing hardware and artificial intelligence software. The artificial intelligence is the trending branch of computer science which interpret the meaning and methods of making computers that behave like human beings. This generation is in the developmental stage.
All the high-level languages are used in the fifth generation of computer. The main aim of the fifth-generation is to make the devices which are capable of self-learning and self-organization. This generation of computer is completely based on artificial intelligence and parallel processing hardware, and artificial intelligence includes the various terms which are given below:

Robotics.
Neural Networks.
Game playing.
Develop the expert system to decide a real-life situation.
Natural language processing.