JNTU B.Pharmacy I COMPUTER APPLICATIONS IN PHARMACY Previous Question Paper (November/December-2020 - R17)

The Hexadecimal number system is a base-16 positional numeral system widely used in computing and digital electronics to represent binary data in a more human-readable and compact format. It utilizes sixteen distinct symbols: the digits 0 through 9 and the letters A through F (or a through f), where A represents 10, B represents 11, C represents 12, D represents 13, E represents 14, and F represents 15.

Each position in a hexadecimal number represents a power of 16, starting from the rightmost position (the least significant digit) as 16⁰. For example, the hexadecimal number 1A3 is calculated as:

The primary advantages of the hexadecimal system include:

• Efficiency in Binary Representation: Since 16 is a power of 2 (16 = 2⁴), each hexadecimal digit corresponds exactly to a 4-bit binary sequence (a nibble). This allows for quick and error-free conversion between binary and hexadecimal.
• Compactness: It significantly reduces the length of binary strings, making it easier for programmers and engineers to read, write, and debug memory addresses, machine code, and color codes in web design.

Conversion to other systems is straightforward. To convert from hexadecimal to decimal, multiply each digit by its corresponding power of 16 and sum the results. To convert from decimal to hexadecimal, perform repeated division by 16 and record the remainders in reverse order. In computer applications, hexadecimal is frequently used to represent memory addresses, character codes (like Unicode), and hardware register settings, serving as a bridge between low-level machine operations and high-level human interpretation.

A Data Flow Diagram (DFD) is a graphical representation that depicts the flow of data through an information system. It illustrates how data enters the system, how it is processed, where it is stored, and where it exits. DFDs are essential tools in systems analysis and design for modeling the functional requirements of a system without specifying the hardware or software implementation details.

The four fundamental components of a DFD are:

• External Entities (Source/Sink): Represented by rectangles, these are individuals, organizations, or other systems that exist outside the boundary of the system being modeled and act as sources or destinations for data.
• Processes: Represented by circles or rounded rectangles, these indicate the activities or functions that transform incoming data into outgoing data.
• Data Stores: Represented by open-ended rectangles or parallel lines, these represent repositories where data is held for later use, such as databases or files.
• Data Flows: Represented by arrows, these show the movement of data between entities, processes, and data stores.

DFDs are structured in levels of increasing detail:

• Level 0 (Context Diagram): The highest level, providing a broad overview of the entire system. It shows the system as a single process interacting with external entities.
• Level 1 (Functional Decomposition): Breaks the system down into its major sub-processes, showing how the main system functions are divided and how they exchange data with data stores.
• Level 2 and beyond: Provide further decomposition of Level 1 processes into more granular sub-processes, offering a detailed view of the system's internal logic.

The primary advantages of using DFDs include improved communication between developers and stakeholders, a clear visualization of system boundaries, and the ability to identify potential bottlenecks or missing data requirements early in the development lifecycle. By focusing on the flow of information rather than the sequence of control, DFDs help ensure that the system design accurately reflects the business processes it is intended to support.