Notes, summaries, assignments, exams, and exercises for Computer science for University

Understanding Assembly Language

Assembly language is a low-level programming language where instructions are written using mnemonic codes rather than binary machine language. An assembler translates these instructions into executable machine code.

Classification of Assembly Instructions

Assembly language instructions are categorized into three primary types:

• Imperative Statements (IS): Specify operations for the processor to perform. These generate executable machine code. Examples include: STOP, ADD, SUB, MULT, MOVER, MOVEM, COMP, BC, DIV, READ, and PRINT.
• Declarative Statements (DL): Used for memory allocation and data definition. DS (Define Storage) reserves memory locations, while DC (Define Constant) stores a constant value in memory.
• Assembler

The Open Web Application Security Project (OWASP)

The Open Web Application Security Project (OWASP) is a non-profit foundation providing guidance on developing, purchasing, and maintaining trustworthy and secure software applications. It's an online community that produces free articles, methodologies, documentation, tools, and technologies in IoT, system software, and web application security.

Key Aspects of OWASP

• Origin: Started by Mark Curphey on September 9, 2001.
• Leadership: Jeff Williams was the volunteer Chair from late 2003 to September 2011. As of 2015, Matt Konda chaired the Board. Bill Corry was an OWASP Foundation Global Board of Directors officer in February 2023.
• Goal: To provide tools, resources, and guidelines to developers, businesses,

Common Bus System Explained

The common bus system is an architecture where a single bus is used for communication between various components of a computer, such as memory, registers, and the ALU. This system minimizes the number of pathways required, thereby simplifying the design and saving space.

Components of a Common Bus System:

• Set of Registers (R1, R2, ...)
• Arithmetic Logic Unit (ALU)
• Control Unit
• Common Bus
• Memory Unit

Operation of a Common Bus System:

• Only one register can place its contents on the bus at a time.
• A control unit uses selection lines and control signals to manage data transfers.
• A multiplexer selects which register’s data will go onto the bus.
• A decoder selects the destination register to receive the data.

Advantages:

• Reduces hardware

Verifying Text Summaries of Relational Data Sets

AggChecker

Building a Sudoku Solver in Java with Backtracking

This document presents a Java implementation of a Sudoku solver, utilizing a classic backtracking algorithm. The code demonstrates how to represent a Sudoku board, check for valid moves, and recursively find a solution to the puzzle.

Initial Sudoku Puzzle Setup

The Sudoku board is represented as a 2D integer array. A value of 0 indicates an empty cell that needs to be filled.

int[][] board = {
  { 8, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 3, 6, 0, 0, 0, 0, 0 },
  { 0, 7, 0, 0, 9, 0, 2, 0, 0 },
  { 0, 5, 0, 0, 0, 7, 0, 0, 0 },
  { 0, 0, 0, 0, 4, 5, 7, 0, 0 },
  { 0, 0, 0, 1, 0, 0, 0, 3, 0 },
  { 0, 0, 1, 0, 0, 0, 0, 6, 8 },
  { 0, 0, 8, 5, 0, 0, 0, 1, 0 },
  { 0, 9, 0, 0, 0, 0, 4, 0, 0 }
};

Implementing

Functions and Arguments

A function is a module of program code that takes input (arguments) and produces output (a return value).

• Arguments allow us to customize the operation performed by the function.
• The return value is often the result of executing the code.
• Calling a function causes the code in a function to execute. If called again, it will execute again.

To document a function, use a multi-line comment immediately after the def line.

Local Variables

Local variables are variables used inside functions.

• They are accessible/usable within that function only.
• This refers to the variable's scope.

Global Variables

Global variables are variables used outside of a function.

• Global variables' scope includes both inside and outside of functions.
• However, since

Stock Market Data Integration

Stock Data Table Headers

Alpha Vantage API Implementation

The following script utilizes jQuery AJAX to fetch real-time stock data for MSFT from the Alpha Vantage API.

function main() {
    $("#list").click(function() {
        $.ajax({
            type: "GET",
            url: "https://www.alphavantage.co/query?function=TIME_SERIES_INTRADAY&symbol=MSFT&interval=1min&apikey=demo",
            success: function (azul) {
                var roxo = azul["Time Series (1min)"];
                for (var verde in roxo) {
                    var vermelho = roxo[verde];
                    var str = "<tr><td>" + vermelho["1. open"] + "</td>"

Understanding Deadlock

A deadlock is a critical situation in which two or more computer programs, sharing the same resource, effectively prevent each other from accessing that resource. This results in both programs ceasing to function or becoming unresponsive.

Historically, the earliest computer operating systems ran only one program at a time, making all system resources available to that single program. As operating systems evolved to run multiple programs concurrently through interleaving, programs initially had to specify their resource needs in advance to avoid conflicts.

The advent of dynamic resource allocation, where programs could request further resources after execution began, introduced the problem of deadlocks. Addressing deadlocks...

IPv6 Packet Format: Base Header

Each IPv6 packet consists of a mandatory base header followed by the payload. The payload is made up of two parts: optional extension headers and the upper-layer data. The base header is 40 bytes long, whereas the extension headers and the data from the upper layer can contain up to 65,535 bytes of information.

The base header has 8 fields:

• Version: A 4-bit field that defines the version of IP, such as IPv4 or IPv6. For IPv6, the value of this field is 6.
• Priority: A 4-bit field that defines the priority of the packet, which is important in connection with traffic congestion.
• Flow Label: A 24-bit field designed for providing special handling for a particular flow of data.
• Payload Length: A 2-byte field used to define