Notes, summaries, assignments, exams, and problems for Computer science

Essential PC Hardware Troubleshooting Topics

• POST Routine Familiarity

  The Power-On Self-Test (POST) routines perform entry-level hardware troubleshooting as a PC starts. Be familiar with the abilities of the POST and its use.

• Diagnosing Port Issues

  When a port isn't functioning, make sure you know the steps to take to ensure that it's physically connected, enabled in BIOS, and recognized in Windows.

• Troubleshooting Hard Disk Systems

  Be aware of the common causes of hard-disk problems, including improper jumper configuration, BIOS Setup, and formatting/partitioning issues.

• Identifying Overheating Issues

  Overheating can cause spontaneous rebooting or shutdown. It's often caused by nonfunctioning cooling fans or improper airflow through the PC.

• Determining

Microprocessors: Core Concepts

A microprocessor is a component that incorporates all the functions of a CPU onto a single integrated circuit.

Technological Characteristics

• Instruction Set: The specific commands the processor can execute.
• Word Size: The number of bits processed in a single operation.
• Clock Speed: The frequency at which the processor operates.
• Pipelining: Processing instructions like an assembly line.
• Bus Width: The data path width for instruction and data transfer.

Processor Architecture Definitions

• Instruction sets and addressing modes.
• Organization of functional units.
• Electronic component technology.

CISC (Complex Instruction Set Computer)

• Extensive Instruction Sets: Features variable-length instruction formats with varying numbers of

Web Engineering Models

Data Model

Compatible with the entity-relationship model and UML class diagrams.

Hypertext Model

• Composition: Site pages, content units of pages.
• Unit: Atomic content element, used to publish the information specified in data models.
• Navigation: Specified by links.
• Links: Between units of a page, between units of different pages, or between pages.
• Defines both the content and navigation.

Presentation Model

• The appearance of web pages.
• Does not include specific elements for conceptual modeling; notations are used.
• XML.
• The presentation is specified using XSL stylesheets.

Web Engineering UML-Based Methodology (UWE)

• Proposal based on UML and the Unified Process, adapted to the web.
• Specific object-oriented techniques are used.
• Proposes an

Memory Management Objectives

• Compare operating system types based on memory management.
• Analyze machine performance based on demand paging and memory allocation.

Fundamentals of Memory Management

Main memory is a linear array of storage locations, each one byte in size.

• Access Time: The duration between the start and end of a read or write operation.
• Memory Cycle Time: The hardware-imposed delay between the end of one operation and the start of the next.
• Address: Physical memory is a sequence of bytes or words, each with a unique address for direct access.

Types of Operating Systems

• Naked Machine: A computer lacking an operating system.
• Dedicated Memory: A system where the programmer directly accesses and manages hardware memory.
• Resident Monitor: Early

Here's a list of essential Linux commands:

• lime - Displays the current calendar.
• lime 1980 - Shows the calendar for the year 1980.
• cal 12 1980 - Displays the calendar for December 1980.
• date - Displays the current date.
• date -s "2009-11-05 18:55" - Changes the system time.
• who - Shows who is currently logged into the system.
• who -u - Displays the process ID (PID) of logged-in users.
• kill -9 3525 - Terminates the process with PID 3525.
• uname - Outputs the machine's name.
• uname -a - Shows detailed information about the machine.
• uptime - Displays how long the machine has been running.
• du - Displays disk space usage by folders.
• du -k - Displays disk space usage in 1024-byte blocks.
• df - Displays disk usage statistics.
• ps - Displays a general list of running processes.

Understanding System Interrupts and Functions

System interrupts are crucial for managing CPU operations and external device interactions. They can be broadly categorized into:

• CPU Interrupts: These are internal events, often referred to as software interrupts or exceptions, triggered by the CPU itself.
• Hardware Interrupts: Caused by external devices, signaling the CPU for attention (e.g., keyboard input, disk I/O).

Essential System Services and Functions

Beyond interrupts, various basic services are available for program interaction with the system:

ROM BIOS Functions

Functions available directly in the system's Read-Only Memory (ROM).

DOS BIOS Services

Basic functions provided by the Disk Operating System (DOS).

DOS Functions

High-level functions for...

Memory Management in Linux

Page Allocation Mechanism

Linux defines a mechanism for dealing with contiguous blocks of pages corresponding to blocks of contiguous page frames in main memory. For this, it uses the buddy system, where the kernel maintains a list of groups of contiguous page frames of fixed size.

Page Replacement Algorithm

The Linux page replacement algorithm is based on the Clock algorithm (also known as NUR or NRU), which associates a use bit and a modification bit with each page in main memory.

Memory Management in Solaris

Paging System

Machine-Independent Data Structures

For paged virtual memory, Solaris uses a series of data structures that are independent of the machine:

• Page Table: Each process has a table with an entry for every

Network Interface Card (NIC)

The Network Interface Card (NIC), also known as a Media Access Unit (MAU), is the device that connects a station (computer or other network device) to the physical network environment. While often presented as an expansion card for computers, many modern computers have integrated network interfaces, primarily Ethernet.

Sometimes, a network card requires a transceiver. This device connects the physical medium to the card, either because a direct connection is impossible (e.g., 10Base5) or because the medium type differs from what the card supports.

Bridge or Bridges

A bridge interconnects two segments of a computer network or divides one network into two segments. It filters data based on the MAC address. Therefore,...

Program Sources

Program sources are files containing instructions for a computer. These must be translated into binary code so the CPU can understand them; therefore, source programs are not written in binary. The software responsible for this translation includes assemblers, compilers, or interpreters. Before translation, all errors must be corrected.

Assemblers

Assemblers transform assembly language directly into its equivalent binary code.

Interpreters

An interpreter is responsible for processing, translating, and executing instructions from a high-level language to machine code one by one. Programs with syntax errors will not run. Interpreters typically provide an editor for writing source code, which facilitates easy error correction. A primary...

Spreadsheet Software and Advantages

Spreadsheet: Infomat is a program dedicated to operations from data arranged in tablas. Ventajas: we can store and retrieve operations later. If we entered data incorrectly, we can modify it without repeating the whole process, and it allows us simulaciones. Además, it can also be used in creating databases, graphics and documents that integrate text, images, results of operations, etc. Las spreadsheets used most include Galco, Gnumeric, Lotus 1-2-3 (IBM) and Microsoft Excel. They disponen of tools and a common work environment because many tasks are similar regardless of the type and application you're using.

Elements of a Spreadsheet

Elements spreadsheet: Table: It is an element that is used to store and...