Notes, abstracts, papers, exams and problems of Computers

80386 Processor State After Reset

After a reset, the 80386 processor is initialized to a specific state to ensure proper operation. Here's an explanation of the processor state after reset:

1. Operating Mode

The processor is initially in Real Mode after a reset. Real Mode is a backward-compatible mode with earlier x86 processors like the 8086/8088. In Real Mode, the processor operates with a 20-bit address bus, allowing it to address up to 1 MB of memory.

2. Segment Registers

The segment registers CS, DS, SS, and ES are set to 0x0000, pointing to the bottom of the physical memory. In Real Mode, these segment registers are 16 bits wide.

3. Instruction Pointer (IP)

The instruction pointer (IP) is set to 0xFFFF, indicating the initial address from which... Continue reading "Understanding the 80386 Processor State After Reset" »

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

Binary Parallel Adder

A binary parallel adder is a digital circuit that adds two binary numbers in parallel, meaning all bits are added simultaneously. It typically consists of full adders arranged in parallel, with each full adder adding corresponding bits from the two input numbers.

BCD Adder

A BCD (Binary Coded Decimal) adder is a specific type of binary parallel adder designed to add two BCD numbers. BCD numbers are decimal digits encoded in binary, where each decimal digit is represented by its 4-bit binary equivalent.

Truth Table for a 4-bit BCD Adder

Here's the truth table for a 4-bit BCD adder:

Diagram

In the truth table:

• A3 A2 A1 A0 represents the first BCD number (A).
• B3 B2 B1 B0 represents the second BCD number (B).
• Cin represents the carry-

Ejercicio de descuentos:

#!/bin/bash

read -p "¿Desea el billete también de vuelta? (s/n): " idavuelta

until [ $idavuelta=="s" ] || [ $idavuelta=="n" ]; do

read -p "¿Desea el billete también de vuelta? (s/n): " idavuelta

done

read -p "¿Tiene carnet joven? (s/n): " carnetjoven

until [ $carnetjoven="s" ] || [ $carnetjoven="n" ]; do

read -p "¿Tiene carnet joven? (s/n): " carnetjoven

done

descuento=0 billete=20

if [ $idavuelta="s" ]; then

descuento=20

billete=" expr $billete \* 2'

fi

if [ $carnetjoven="s" ]j then

descuento=30

fi

costefinal=`expr $billete \* \( 100 - $descuento \) / 100`

echo "El precio final del billete es $costefinal"

Ejercicio de medias:

#!/bin/bash

acu=0

cont=0

read -p "Introduce un numero: " num

while [ $num -ne 0 ]; do

acu=`expr $acu + $num`

cont=... Continue reading "Shell script" »

Kako si lep danes 

What is Lorem Ipsum?

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

What is Lorem Ipsum?

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard... Continue reading "dsdfs" »

DIRECTORY COMMANDS

– Directory commands: Commands that work with directories (pwd, ls, cd, mkdir, rmdir)

– File commands: Commands that allow you to manage files (cp, mv, sort, cut, paste, diff, rm, uniq)

pwd it lets you know where you are in the tree

Basic listing (ls): Displays files and directories in your current directory.

-F  To distinguish between files and directories

-a  show hidden files starting with a dot (.)

 -l parameter to produce a long listing.

Allows you to make copy of a file. 

– cp [option] source destination 

 -i option for interactive mode to give you a warning before overwriting an already existing file. 

 -p option to preserve file access or modification times of the original file for the copied file.

Copy from current

HOSTàROUTER: 1

ENABLE

CONFIGURE TERMINAL

INTERFACE GIGABITETHERNET 0/0

IP ADDRESS 192.168.1.126 255.255.255.224

NO SHUTDOWN

EXIT

INTERFACE GIGABITEETHERNET 0/1

IP ADDRESS 192.168.1.158 255.255.255.240

NO SHUTDOWN

HOSTàSWITCH 2

ENABLE

CONFIFURE TERMINAL

INTERFACE VLAN 1

IP ADDRESS 192.168.1.157 255.255.255.240

NO SHUTDOWN

HOST/ROUTER 3

EXIT (LLEGAR AL CONFIGURE TERMINAL)

HOSTNAME MIDDLE

ENABLE SECRET CISCO

LINE CONSOLE 0

PASSWORD CLASS

LOGIN

EXIT

SECURITY PASSWORD MIN-LENGTH 10

SERVICE PASSWORD ENCRYPTION

IP DOMAIN-NAME CISCO

CRYPTON KEY GENERATE RSA

1024

EXIT

USERNAME CICLOS

LINE VTY 0 4

LOGIN LOCAL

TRANSPORT INPUT SSH

EXIT

INTERFACE GIBABITEETHERNET 0/0

IPV6 ADDRESS 2001:DB8:ACAD:A::1/64

IPV6 ADDRESS FE80::1 LIN

EXIT

GIBABITETHERNET 0/1

IPV6 ADDRESS 2001:DB8:ACAD:B::1/64

IPV6

A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code.^[1] When this replication succeeds, the affected areas are then said to be 'infected' with a computer virus.^[2][3]

Virus writers use social engineering deceptions and exploit detailed knowledge of security vulnerabilities to initially infect systems and to spread the virus. The vast majority of viruses target systems running Microsoft Windows,^[4][5][6] employing a variety of mechanisms to infect new hosts,^[7] and often using complex anti-detection/stealth strategies to evade antivirus software.^{[8][9][10][11]} Motives for creating viruses can include seeking profit (e.g., with ransomware), desire... Continue reading "Understanding Computer Viruses and Network Topologies" »

Javascript Continued