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

Communication Modes

Operability:

• Simplex Communication: Clearly defined transmitter and receiver functions. Transmission occurs in one direction only. Example: a TV broadcast using a single physical channel and a single unidirectional logical channel.
• Half-Duplex Communication: Two-way communication where sender and receiver roles are interchangeable, but transmission is not simultaneous. When one device sends, the other must receive. It uses one physical channel and a bidirectional logical channel.
• Full-Duplex Communication: Bidirectional and simultaneous communication. Sender and receiver roles are not strictly defined.

Data Circuit Components

Circuit Data:

• Data Terminal Equipment (DTE): The source or destination of information.
• Data Circuit-Terminating

Image Processing

Imaging Technique

• Bitmap (Raster): Formed by pixels, each with a color. Programs: GIMP, Photoshop. Formats: GIF, JPEG, BMP, TIFF, PNG, PCX (Paintbrush), RAW, TGA, PSD (Photoshop), XCF (GIMP).
• Vector: Obtained using lines. Programs: Corel Draw, OpenOffice.org Draw, AutoCAD, QCad. Formats: DXF, CDR, DWG, ODG/SXD, SWF, AI, SFHx.
• 3D: Three-dimensional figures. Widely used in games. Programs: Virtual Hammer.

Memory Cards

• SD
• MMC
• XD
• Memory Stick

Image Properties

• Color Depth: Total number of bits used to encode an image. More depth means more shades.
• Brightness: Related to light intensity emitted over a given area.
• Contrast: Brightness difference between the maximum and minimum brightness.

Color Specification Systems

• RGB (Red, Green, Blue): Used

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" »

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" »

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" »

Understanding Computer Memory

Memory Types

Main Memory

Main memory is integrated into the system's firmware and directly governed by the CPU. It stores the boot process, data from the stack, memory-resident programs, and the user program currently executing.

Types of Main Memory:

• Ferrite memories (obsolete)
• Integrated memory:
  • RAM (Random Access Memory)
  • ROM (Read-Only Memory)
  • PROM (Programmable ROM)
  • EPROM (Erasable Programmable ROM)
  • OTP Memory (One-Time Programmable ROM)
  • EAROM (Electrically Alterable ROM)

Cache Memory

Cache memory is located within the CPU and communicates directly with it. It stores frequently used data to reduce access time from main memory.

Mass Memory

Mass memory refers to storage devices with higher capacity, typically peripherals.

Types