Fundamentals of Computer Systems and Software

Hardware

Physical components of a computer system.

Software

Programs enabling computer functionality. It runs on the hardware.

System Software and what's included (4)

Software required to operate hardware, so it works together for the computer to function. It includes the

-operating system

-utilities

-programme translators

-libraries

Application Software

Programs completing tasks for the user. It's what apps are used to make the computer useful, e.g. video editing or a web browser app

Operating System

Controls the operation of the hardware in the computer. It's the platform that other software runs on.

Utility Programs and 4 areas it overviews

Software optimizing computer performance and tasks. such as a disk defrag etc.

-maintenance

-optimisation

-configuration

-analysis

Disk Defragmenter

Reorganizes fragmented files for efficient storage.

Virus Checker

Scans for and removes computer viruses.

Libraries

Pre-compiled / prewritten programs and functions available for reuse.

Translators

Convert programming languages into executable code (To assembly code or straight to machine code)

Compilers

Translate high-level code into machine code, al

Interpreters

Execute code line-by-line at runtime.

Assemblers

Convert assembly language to machine code.

Special-Purpose Software

Designed for specific tasks or functions.

Bespoke Software

Custom software tailored to user requirements.

Virtual Machine

Emulates hardware to run software environments.

Memory Management - OS task

recording how memory in the computer is divided and identified so that memory is allocated efficiently between processes that are running

Controls computer memory allocation and usage.

Resource Management

Oversees hardware resources like CPU and memory. optimised the resourced available.

User Interface

Facilitates user interaction with the computer. In the interest of the person using the computer and their easy use.

Programming Language Translators

Convert code between programming languages.

RAM

Temporary storage for active programs and data. any current running programs grab from the pool of RAM

Virtual Memory

Hard disk space used as additional RAM. borrowing disk space for current running programs

Processor Scheduling - OS task

Allocating CPU time among multiple tasks.

Scheduler

Module that optimizes processor time usage.

Multi-user System

System allowing multiple users to operate simultaneously.

Response Time

Time taken to respond to user requests.

Interrupt handline - OS task

dealing with requests that disrupt the processor's work

Command Line Interface

Text-based interface for user commands.

Graphical User Interface

Visual interface with windows and icons.

Embedded Systems

OS designed for specific hardware applications.

Machine Code

Binary instructions directly executed by the CPU.

Opcode

Operation code indicating the instruction type.

Assembly Code

Low-level language using mnemonics for instructions.

High Level Programming Language

Code that abstracts machine instructions significantly.

Bletchley Park

Site of early computer development during WWII.

Enigma Code

Cipher used by Germans in WWII.

Memory Cell

Basic unit of storage in a computer.

Imperative Languages

High-level languages with command-based instructions.

FORTRAN

First high-level programming language for formulas.

Imperative Programming

Program structure as sequential instructions modifying memory.

Functional Programming

-Uses functions and mathematical operations to input and output data.

-There are no mutable variables, so it is good for process big data with no risk of changing it.

Assembler

Converts assembly code to machine code.

Compiler

Translates high-level code into machine code.

Interpreter

Translates and executes code line-by-line.

Bytecode

Intermediate code executed by a bytecode compiler.

Logic Gates

Devices that perform logical operations on inputs.

Boolean Algebra

Mathematical structure for binary variables and operations.

De Morgan's Laws

Rules relating conjunctions and disjunctions in logic.

X · 0 = 0

Multiplication with zero results in zero.

X · 1 = 1

Multiplication with one retains the value.

X + 0 = X

Addition with zero retains the value.

X + 1 = 1

Addition with one results in one.

X · X = X

A variable ANDed with itself equals itself.

X + X = X

A variable ORed with itself equals itself.

D-type Flip-Flops

Memory cells that store one bit, triggered by clock.

Concatenated Adder

Combines multiple adders for n-bit binary addition.

Positive Edge-Triggered

Changes state only at rising clock edges.

Characteristics of high-level programming languages (5)

- Syntax that is easy for humans to understand

- Syntax that uses command words similar to natural human language

- A single line of code can accomplish multiple tasks

- Allow the programmer to focus on what the program is trying to achieve rather than how the computer or specific hardware operates

- Source code is translated into machine code for the computer to process

Advantages of high-level languages

- Easier to write statements as they are closer to the human language

-it is Portable, so can compiled/translated to be run on different devices

- Libraries can be downloaded so coders can utilise pre-written code

what imperative and procedural refer to

procedural is a type of imperative language.

They both describe the function or method the computer should use to solve a problem.

It's code that runs one after another. procedural refers to the use of breaking it into functions/procedures.

Built-in functions

Used by high level languages. It's functions that are prewritten, so can be used repeatatively by programmers.

They don't need to know the complexity of the how the function operates, but just know that it does the job. For example, the 'Print' function in Python.

Object Oriented Pillars

Abstraction, Encapsulation, Polymorphism, Inheritance

Secondary Storage Management - OS task

tracking where files and programs are stored and which parts are available for storage, and managing files and folders based on user permissions

Input/Output device management - OS task

ensuring efficient communication with devices and managing functionality issues

Security - OS task

Levels of authority and access management. For example a computer user login, Admin locks, Limited file access.

Peripheral Devices

all the other external, physical components of the computer such as the input and output devices (mouse, keyboard, webcam etc)

a table of CRUD, HTML and SQL equivalents

CRUD

CREATE RETRIEVE UPDATE DELETE

SQL

CREATE SELECT UPDATE DELETE

HTML

POST GET PUT DELETE

REST

architecture that implements CRUD between apps.

It allows them to be programmed individually but have a successful interaction

Websockets

Provides a connection where clients and servers can send data bi-directionally at any given time. used for real-time applications.

Pushy Servers via Websockets

The websocket provides a connection where data can be sent without https. This means the heavy headers are not needed

- reduced latency and traffic

-no need for security checks

Websocket Protocol - how it functions

Uses the Transport layer of the TCP/IP stack

WebSocket use port numbers (80 or 443 is encrypted) to the firewall acts like its regular web traffic.

It transports messages made of one or more frames. these are reconstructed when recieved

Frames within a WebSocket message

Binary frames

text frames - images

Ping/Pong frames - check connection

Control Frames - end connection e.g.