IT : Hardware and System Software - LU2 and LU3

Overclocking

The practice of making computer components run at speeds faster than designed by manipulating the frequencies at which the component is set to run.

Overclocking per component

The CPU operates faster than the system clock by changing its own clock multiplication factor.

Overclocking the whole system

The system clock is increased affecting all components that detect the system clock and multiply by a factor.

Dangers Of Overclocking:

Components run faster than they were designed, causing them to become unstable or fail

Machine cycle

• FETCH a programme from memory(RAM or Cache) (Data Bus)

• DECODE the instruction(Use CPU instruction set)

  (Address Bus)

• EXECUTE the instruction, using data, if necessary

• STORE the result in main memory or send to an output device(Control Bus)

PCI Express

Peripheral Component Interconnect Express

• Used to connect Graphics Cards, RAID Cards, Wi-Fi cards or SSD’s to the motherboard.

SATA

Serial Advanced Technology Attachment

• Used to connect mass storages (Hard Drives/ SSD’s) to motherboard

NVMe

Non-Volatile Memory express

• Connects SSD’s to motherboard

• NVMe allows SSD’s to read/write at much higher speeds than SATA

Browser Cache

Every time a website is accessed, a copy of the website is kept in the browser cache in local hard disk.

This cache also stores all files downloaded from the web

Stores all cookies.

Web Cache

Also known as Proxy Server Cache

Stores all the recently accessed web pages on a server in a network.

Web cache is a shared storage of previously downloaded web pages, images, etc on a server of an organisation.

If anyone on the network tries to access a previously accessed website, site will be delivered from organisations server, not the web server, reducing network traffic and making server quciker.

BIOS

Basic Input Output System

• Low level software

• Stored in non-volatile ROM chip on MOBO

• Firmware

• Responsible for POST

UEFI

Unified Extended Firmware Interface

• Replaces BIOS

UEFI vs BIOS

• UEFI boot from drives of 2.2TB or larger

• Can run in 32 or 64 bit mode, more address space than BIOS meaning it boots faster

• UEFI setup screen more user friendly with graphics and mouse cursor support , BIOS Has no capability for using mouse and graphics drivers.

Multitasking vs multiprocessing and multithreading

Multitasking:

• Appear to be running several programs simultaneously

• CPU switches very short bursts of processing time

• The ability of an OS to execute more than one task simultaneously on a single processor machine

Multiprocessing:

• Having multiple CPU’s, Called CORES on a single CPU chip

• Entire core is duplicated on CPU Chip

• Multiple core many processes can run at the same time

Multithreading:

• When more than one task in the same program can be executed at the same time

• Each thread can be executed by a separate CPU

Virtual Memory

• When RAM is full, OS can use a section of the hard disk and extend it as RAM

• Virtual memory extends number of addresses RAM has and requires pages to be swapped between RAM and hard disk

Compilers vs Interpreters

Compiler: A compiler translates code from a high-level programming language into machine code before the program runs.

Interpreter: An interpreter translates code written in a high-level programming language into machine code line-by-line as the code runs. Python OR JavaScript