System Calls: Types and Structure
System Calls
1. Memory Management
All data must be in memory before and after processing. All instructions must be in memory in order to execute.
Activities:
- Optimizing CPU and computer response to users.
- Keeping track of which parts of memory are currently being used and by whom.
- Deciding which processes (or parts thereof) and data to move into and out of memory.
- Allocating and deallocating memory space as needed.
2. Storage Management
- Files are usually organized into directories.
- Access control on most
Understanding Data Organization: Files, Records, and Structures
Understanding Data Organization
LOGICAL RECORD – A homogeneous unit of information composed of data relating to a particular object or concept.
FIELD – An elementary unit of information within a logical record.
PHYSICAL RECORD – A unit of transmission or storage of information in auxiliary memory. It is a set of information that, depending on the characteristics of the machine, can be stored or read at one time. Often called a BLOCK. In general, a block consists of a variable number of logical records,
Read More8085 Microprocessor: Addressing Modes, Interrupts, and Pipeline
8085 Instruction Addressing Modes
These instructions transfer data between registers, memory, and registers without altering the content. Addressing modes in 8085 are classified into 5 groups:
Immediate Addressing Mode
In this mode, the 8/16-bit data is specified in the instruction itself as one of its operands. For example: MVI K, 20F means 20F is copied into register K.
Register Addressing Mode
In this mode, data is copied from one register to another. For example: MOV K, B means data in register B
Monitor and Graphics Technologies: A Deep Dive
CRT (Cathode Ray Tube) Monitors
CRT monitors were once the most common type. They work by directing red, green, and blue electron beams across a phosphorus-coated screen. The phosphor glows when struck by the electron beam, while areas not struck remain dark. The combination of glowing and non-glowing areas creates the image.
LCD (Liquid Crystal Display) Monitors
LCD monitors consist of two polarizing filters with a liquid crystal solution between them. An electronic current aligns the crystals, allowing
Read MoreNRZ, MDT, MDF, ISDN, and Passive S0 Bus Explained
NRZ, MDT, MDF, ISDN, and Passive S0 Bus
NRZ (Non-Return-to-Zero): One of the drawbacks of NRZ is that the signal must be accompanied by synchronization pulses, i.e., the clock signal. Without this, it’s impossible to determine bit synchrony. Therefore, a separate channel is required exclusively for the clock signal, leading to resource wastage.
Symbol Distortion: Bandwidth limitation and the transmission of digital information require significant bandwidth. Because the signal is square, it necessitates
Read MoreDesign Patterns: Effective Software Development
Introduction
Standards are an effective way to reuse project. Patterns are solutions to specific problems that occur recurrently in a given context that were identified from the collective experience of software developers. The main advantage of using standards is because it describes software abstractions, including:
- Common vocabulary
- Effective communication of complex principles, helps to document the software architecture
- Capture the essential parts of a compact design
Design Patterns
However, the
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