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

What is a Computer?

A computer is an information processing machine capable of storing a large amount of data.

What is an Abacus?

The Abacus was a device capable of performing automatic calculations.

What is the Computer's Brain?

The computer's brain is the microprocessor.

What is Multimedia?

Multimedia is the ability to use images and sound through the computer.

What is the Internet?

The Internet is a network that allows access to information stored on computers.

What is Compatibility?

Compatibility refers to the ability of different components or software to work together.

What is a Power Supply?

The power supply is a component that connects your computer to the electric current.

What is the Motherboard?

The motherboard is the main circuit board of a computer,... Continue reading "Understanding Computer Fundamentals: FAQ" »

Flip Flop XR

library ieee;

use ieee.std_logic_1164.all;

Entity FFXR is

Port( clk, x, r : in std_logic;

q: buffer std_logic);

End FFXR;

Architecture Behavior of FFXR is

Begin

Process

Begin

Wait until clk 'EVENT' and clk='1';

if x='0' then

if r='0' then

q <= not q;

Else

If r='0' then

q <= '0';

Else

q <= q;

End If;

End If;

End Process;

End Behavior;

Multiplexer 4-to-1

library ieee;

use ieee.std_logic_1164.all;

Entity Mux_4_1 is

Port(aB:... Continue reading "Understanding Flip Flop and Multiplexer Designs in VHDL" »

Key Computer and Software Terms

1. Text Editor: It is a program through which we can enter text without a specific file format.

2. Word Processing: It serves not only to write, but also to format the text and offer a better appearance.

3. Document: A data file with a specific format that is interpreted by the processor.

4. Book: An entire document with all its pages.

5. Section: An organizational unit of the document that may implement a number of characteristics.

6. Paragraph: An organizational unit below a section.

7. Style: A way of sorting, identifying, and storing a set of formatting and other features.

8. Index: A part of the document, usually found at the end.

9. Table of Contents: An index with page layout format which summarizes the contents... Continue reading "Key Computer & Software Terms: Definitions & Concepts" »

The scanner is a computer input device that allows you to scan images or documents using Optical Character Recognition (OCR). It emits light onto the document being scanned and captures the reflected light using a photosensor.

Types of Software

• OCR (Optical Character Recognition): Software specializing in extracting text characters from scanned document images, converting them into editable text.
• OMR (Optical Mark Recognition): Software designed to extract marks from documents, storing them as database fields.

Transmission of Photographs

• Wired: Traditional cable connections.
• Card Reader: For transferring data from memory cards.
• Infrared: Transmits and receives waves in the infrared spectrum. Requires devices to be side-by-side for communication (2-

RHQ Configuration

Hostname: rhq

Username: isp

Password: 0 duocuc

Interface Configuration

FastEthernet0/0

• IP Address: 172.31.0.1 255.255.0.0
• IP NAT Inside
• Duplex: Auto
• Speed: Auto

Serial0/0/0

• No IP Address
• Encapsulation: Frame-Relay

Serial0/0/0.100 (Point-to-Point)

• Bandwidth: 512
• IP Address: 10.10.0.1 255.255.0.0
• Frame-Relay Interface-DLCI: 100
• IP OSPF Authentication: Message-Digest
• IP OSPF Message-Digest-Key: 1 MD5 cisco
• IP NAT Inside

Serial0/0/0.200 (Point-to-Point)

• Bandwidth: 512
• IP Address: 10.11.0.1 255.255.0.0
• Frame-Relay Interface-DLCI: 200
• IP OSPF Authentication: Message-Digest
• IP OSPF Message-Digest-Key: 2 MD5 cisco
• IP NAT Inside

Serial0/0/1

• IP Address: 200.10.10.2 255.255.255.0
• Encapsulation: PPP
• PPP Authentication: CHAP
• IP NAT Outside

Routing Configuration

Router... Continue reading "Network Configuration: RHQ, ISP, Rconcepcion, Rsantiago" »

Model 802
IEEE defined in the 80s
Responsible for defining communication,
transmission, and use of LANs.

802.1: Definition Network International
We define that the network devices should be identified by 48 bits where the first 3 bytes are defined by the IEEE. This identifier must be unique for each product.

802.2: Logical Link Control (LLC)
It defines the controls for the transmission, i.e., defines handshaking.

802.3: Method of Access to the Medium
It defines the access method or wireless LAN, and collisions are resolved by the present CSMA/CA and CSMA/CD.

802.5: Token Ring
It defines the logical and physical topologies of Token Ring.

802.11: Wireless Networks (WiFi)
Establishes standards for speed, frequency, and scope in local wireless transmissions.... Continue reading "Understanding IEEE 802 Standards for Networking" »

Understanding MS-DOS CONFIG.SYS Configuration

The CONFIG.SYS file is crucial for configuring various system components, including MS-DOS, hardware, and applications, ensuring they function as intended.

System configuration information is primarily stored in the CONFIG.SYS file.

What is CONFIG.SYS?

It is a text file that contains special commands that configure computer components such as hardware (memory, keyboard, mouse, printer) for use by MS-DOS and applications.

It is the first file that runs when you start MS-DOS.

Location of CONFIG.SYS

It is usually located in the root directory, C:\.

CONFIG.SYS Runtime

MS-DOS executes this file each time you start your computer. However, if needed, you can instruct the system to skip it.

Why Modify CONFIG.SYS?

Repeaters

Repeaters: are network elements that regenerate the electrical signal that arrives in order to restore it to its original level, thus avoiding problems that might occur due to excessive attenuation. They operate at the physical layer of the OSI model, since they work with signals.

Hubs

A hub has the advantage of simply copying bits from other network segments. It requires no special configuration, being based on the physical layer. It serves no network addresses, protocols, services, etc. It simply repeats the signal from the network at high speed. It does not isolate the traffic problems generated by the network in each of the segments.

Bridges

Bridges: provide some capacity or element of control. They can accept and forward the frames... Continue reading "Understanding Repeaters, Hubs, Bridges, Switches, and VLANs" »

Data Link Protocols

LAPB, LAPF, and LAPD

These are Data Link protocols:

• LAPB (Link Access Procedure, Balanced): A subset of HDLC, providing asynchronous balanced mode (ABM) for point-to-point links between user systems and packet-switching network nodes.
• LAPF (Link Access Procedure for Frame-Mode Bearer Services): Includes a control protocol (similar to HDLC) and a core protocol (subset of the control protocol). LAPF control uses ABM and 7-bit sequence numbers. LAPF core has flag, address, information, and FCS fields, but no control field.
• LAPD (Link Access Procedure, D-Channel): Provides data link control over the ISDN D channel. Uses ABM, 7-bit sequence numbers, a 16-bit CRC FCS, and a two-part address field for device and logical user identification.

Oracle Tablespaces and Data Storage

System tablespaces and the required sysaux tablespace are created when the database is created and must be online.

The System tablespace is used for core functionality, for example, the data dictionary tables.

The auxiliary Sysaux tablespace is used for additional database components, such as the Enterprise Manager repository.

A tablespace accounts for one or more data files.

Data files belong to one tablespace.

User process: It begins when the user database server requests a connection to Oracle.

Process server: Connects to the Oracle instance and starts when a user establishes a session.

Background processes: Start the Oracle instance.

Oracle is a server management system database that provides an open, comprehensive,... Continue reading "Oracle Tablespaces, Segments, and Data Blocks Explained" »