Notes, summaries, assignments, exams, and problems for Computers

Algorithms

Algorithms involve inputs, instructions, outputs, and a purpose.

Instruction Types

• Instruction
• Decision
• Loop
• Variable
• Function

Python Basics

Comments

Comments explain what code is for, intended for human readers.

Variables

Storing a value in a variable is called assignment. It's best practice not to use generic names.

Calculations (Operators)

• + : Addition
• - : Subtraction
• * : Multiplication
• / : Division
• // : Integer Division (e.g., 6 // 4 = 1)
• % : Remainder / Modulo (e.g., 6 % 4 = 2)
• ** : Exponentiation

mass_in_kg = 15

weight_in_pounds = mass_in_kg * 2.2

print('the weight in pounds is: ', weight_in_pounds)

user_name = input("enter your user name: ")

print('hello', user_name)

Data Types

• int: Integer numbers (e.g., -1, 0, 2, 1000)
• float: Floating-point (real)

Lecture 1: Moore's Law

Moore's Law: The number of transistors on microchips doubles every two years.

Lecture 2: Logic Gates

AND, OR, and NOT gates are universal.

Logic word problem steps:

Example: In a bank, there were four employees: the bank manager, assistant manager, teller, and the security guard. The bank has a single vault for the storage of their money. This vault was designed so that it needs four signals to open it. These four signals are from the bank manager, assistant manager, teller, and the security guard. For the vault to open, it needs the following conditions:

1. No single employee can open the vault.
2. It can be opened with three employees as long as one of them is the manager.
3. It can be opened by the manager together with the assistant

A stack is a fundamental data structure in computer science that follows the Last In, First Out (LIFO) principle. This means that the last element added to the stack is the first one to be removed. You can think of it like a stack of plates: you can only add or remove the top plate.

### Key Concepts of a Stack:

1. Basic Operations:
   - Push: This operation adds an element to the top of the stack.
   - Pop: This operation removes the element from the top of the stack and returns it.
   - Peek (or Top): This operation returns the top element of the stack without removing it.
   - IsEmpty: This operation checks whether the stack is empty.

2. Implementation:
   Stacks can be implemented using arrays or linked lists. Here are the details for... Continue reading "Mastering Stacks, Deques, Trees, and Graph Data Structures" »

Microprocessor vs. Microcontroller

ii) Differentiate Between a Microprocessor and a Micro-Controller

Microprocessor

Definition:

A microprocessor is a central processing unit (CPU) on a single integrated circuit (IC) chip that performs the processing functions of a computer.

Functionality:

• It only includes the CPU core and lacks other components like memory, I/O ports, timers, and other peripherals.
• Requires external components like memory (RAM, ROM), input/output devices, timers, and other peripherals to function as a complete system.

Usage:

• Primarily used in systems requiring high computational power and flexibility, such as desktop computers, laptops, servers, and high-end embedded systems.
• Suited for applications where customization of peripherals

Essential Linux Commands

File and Directory Management

• mkdir: Create a new directory.
• ls: List contents of a directory.
• rm: Remove files or directories (-r for recursive).
• cp: Copy files or directories.
• mv: Move or rename files or directories.
• cat: Display file contents or create files.
• less: View file contents one page at a time.
• head: Display the first 10 lines of a file.
• tail: Display the last 10 lines of a file.

System Information

• uname: Show system information (kernel, version, etc.).
• top: Display running processes and resource usage.
• df: Show disk space usage.
• df -h: Show disk usage in human-readable format.
• free: Display memory usage (RAM and swap).

File Creation and Editing

• touch: Create an empty file or update its timestamp.
• echo: Write text to a file

1. TCP Congestion Control

Slow Start: TCP initializes congestion window (cwnd) to a small size and doubles it every Round Trip Time (RTT) until a loss occurs (exponential growth) or the slow start threshold is reached.

Congestion Avoidance: After reaching the threshold, cwnd is incremented by one segment for each RTT, growing linearly to avoid congestion.

Fast Recovery: When triple duplicate ACKs are detected, TCP halves the cwnd and reduces the slow start threshold to half of the cwnd size before the loss, then transitions to congestion avoidance.

2. TCP RTT and Timeout

Estimating RTT: Uses Smoothed Round Trip Time (SRTT) which is a weighted average of previous RTT measurements.

Timeout Calculation: Often calculated as Timeout=SRTT+4×RTT

Windows Popularity and Vista Features

Unit 13

Interviewer: There is no doubt that Windows has revolutionized the way we use computers today. Bill, can you explain just why it’s so popular?

Bill: Well, very simply, people find Windows very easy to use because everything is presented in graphic images. It’s also compatible with thousands of programs.

Interviewer: The big news at the moment is, of course, the launch of Windows Vista – the successor to Windows XP. I understand that there are several versions of Vista available. Could you give us some advice on which one to get?

Bill: Yes, you’re right – there are four main editions: Home Basic, Home Premium, Business and Ultimate.

Windows Vista Editions:

• Home Basic: Designed for users with basic

Unit 14: Moving Text

Cutting and Pasting

Anna: Ben, do you know how I can move this paragraph? I want to put it at the end of this page.

Ben: I think so. First, select the text with your mouse. Then, choose "Cut" from the Edit menu.

Anna: Like this?

Ben: Yes. The text disappears and is copied to the Clipboard. Click where you want the text to go.

Anna: Okay. Is that right?

Ben: Yes, if that's the correct spot. Next, choose "Paste" from the Edit menu, or press CTRL+V.

Anna: Okay, done. Is that all?

Ben: Yes. If you make a mistake, choose "Undo" from the Edit menu to reverse your last action.

Anna: Brilliant! Thanks!

Ben: You're welcome.

Unit 15: Spreadsheet Fundamentals

Introduction

Let's start with the basics. Spreadsheets are used in business for financial... Continue reading "Spreadsheet Basics and Text Editing Tips" »

What is Mathematical Logical Thinking?

These are the skills students develop associated with logical and mathematical concepts, reasoning, comprehension, and exploration of the world through real proportions, thus strengthening more abstract aspects of thought.

Geometry with Dinosaurs

This activity involves cutting out various geometric shapes with EVA rubber. Children will then create their own dinosaurs using these shapes. Through this activity, they can learn geometric shapes, count the number of elements used in each dinosaur (like the sides of the shapes), and create new geometric shapes from the ones they already have.

Logical Reasoning with Chupa Chups

This activity consists of creating logically structured material and playing with it using... Continue reading "Developing Logical and Mathematical Thinking in Children" »

Performance Metrics

• Elapsed Time: Represents overall system performance. It is the total time taken to complete a task.
• User CPU Time: Indicates CPU performance. It is the time the task actively runs on the CPU, excluding idle time.
• CPU Time: The time the CPU spends executing instructions, either from the task or the operating system, excluding idle time.
• Clock Speed: 1 MHz equals 1 million clock cycles per second. 1 GHz equals 1 billion clock cycles per second.
• Response Time: Equivalent to execution time.
• Throughput: Equivalent to bandwidth.
• Performance Comparison: (PerfA) / (PerfB) = (ExecTimeB) / (ExecTimeA) = n

Impact of Processor Upgrades

• Replacing a processor with a faster one decreases response time and increases throughput.
• Adding an additional