Data Link Layer Protocols: Services, Framing, and Error Control
Data-Link Layer Service Categories
Describe the three possible categories of services provided by the data-link layer:
Unacknowledged Connectionless Service
- This service is appropriate when the error rate is very low, so recovery is left to higher layers.
- It is also appropriate for real-time traffic, such as voice, where late data are worse than bad data.
Acknowledged Connectionless Service
- No logical connections are used, but each frame sent is individually acknowledged.
- Thus, the sender knows whether
Input/Output Systems, Storage, and CPU Security Mechanisms
Types of I/O Devices
Block Devices
Store data in fixed-size blocks. Data transfer happens in blocks (e.g., SSD).
Character Devices
Handle a stream of characters with no block structure (e.g., Keyboard, Mouse). They do not support seek operations.
Block vs. Character Devices
Block devices support random access and block-level operations, while character devices operate in a stream and cannot seek.
I/O Communication Methods
Separate I/O and Memory Space
Provides easier separation but is less flexible.
Memory-
Read MoreMastering C Programming Concepts: Data Structures, Control Flow, and File I/O
Two-Dimensional Arrays and Matrix Addition in C
A two-dimensional array (2D array) is a type of array that stores data in a matrix format, consisting of rows and columns. It can be visualized as an array of arrays. Each element in a 2D array is accessed by two indices: the row index and the column index.
Declaration of a Two-Dimensional Array
In C language, a 2D array is declared using the following syntax:
data_type array_name[rows][columns];Example: To declare a 2×2 integer matrix:
int matrix[2][2]Fundamental Definitions in Computer Systems and Programming
Core Concepts in Computer Architecture and Data Handling
Input-Output Interface (I/O Interface)
The Input-Output Interface (I/O Interface) is a method used for transferring information between internal storage devices (i.e., memory) and external peripheral devices. A peripheral device provides input and output for the computer and is often called an I/O device.
Examples of Peripheral Devices:
- Input Devices: Keyboard and mouse.
- Output Devices: Monitor and printer.
- Both Input and Output: External hard drives
Database and Algorithm Fundamentals: Essential Concepts Q&A
Database Structure and Relationships
Database Relationships: How They Function
Relationships work by matching data in key fields, usually a field with the same name in both tables. In most cases, the matching fields are the primary key of one table and a foreign key in another.
Most Common Database Relationship Type
The most common type is the One-to-Many relationship. In this structure, a record in Table A can have many matching records in Table B, but a record in Table B has only one matching record
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Algorithm Analysis vs. Algorithm Design Difficulty
When performing algorithm analysis, an algorithm already exists. The task involves applying established rules of analysis, such as:
- Rules for sequence structure.
- Rules for selection structure.
- Rules for repetition/iteration structure.
- Recurrence rules for recursion.
While some algorithms involve complex nested structures, the analyst always has a “specimen” to study and analyze. This is not the case when one has to design an algorithm.
Algorithm design
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