Lesson Objectives Aims Key Words Be able to describe the role and purpose of the BIOS Understand the role of drivers in a computer system Understand how virtual machines work and the need for virtualisation Key Words

The boot process Power on Bios Boot loader Kernel / Drivers Desktop

BIOS steps BIOS is loaded from ROM CPU begins executing instructions Power on BIOS is loaded from ROM CPU begins executing instructions POST Power On Self Test Scans for (enumerates) and initialises hardware Looks for hardware changes Performs basic tests (does not guarantee function) Boot Loader Selects the first boot device based on information collected in the POST. Tries the boot loader of that device and, if successful, runs the OS. Moves on to the next boot device if unsuccessful. Repeats until all boot devices have been tried. If no boot devices have suitable boot loaders, the system will stop.

BIOS First widely used in the early 1980’s A 16 Bit system Meaning processors have to “emulate” 16 bit mode at power on! Can only access 1mb RAM Limited functionality 2TB disc limit No support for security etc

The BIOS includes: A configuration utility Saved pointers to the location of boot devices in order of preference. BIOS will attempt to read the boot sector (usually the first sector on a disc), if this is valid it usualy points to the boot loader which loads the operating system.

UEFI

UEFI An OS in its own right A “firmware” rather than BIOS Extensible and modular Support for secure boot Support for absurdly large discs (billions of GB’s) Easier integration with OS’s – change configurations without booting Can access and store data in an EFI disc partition Used by all new PC’s and Macs (since 2008)

VM’s Computers are now incredibly well resourced Sales of PC’s have fallen away, in part due to the fact there is no longer a 1-2 year upgrade need This power brings with it the opportunity to consolidate hardware, especially in a server environment

Virtualisation: The emulation of generic PC hardware, through software “Virtualised” systems believe they have sole access to the resources allocated to them OS’s and software is installed exactly as normal Generic drivers/hardware mean degraded performance in some application

Server side Machines can be: Cloned Multiple VM’s on one single physical machine Managed separately Repaired/maintained without affecting other services Snapshotted – much easier recovery/backup This makes greater use of hardware resources – rarely is a server at 100% load.

Drivers Drivers are software that allow hardware resources to function with the operating system. Why are drivers necessary?

Drivers Allow operating systems to be “extended” to work with a wide ranger of peripherals Responsibility on manufacturers to provide stable code and feature implementation Removes OS complexity Modularity

Review/Success Criteria You should know: The boot process in a PC The purpose of the BIOS Features of BIOS The differences between BIOS and UEFI The need for UEFI What virtualisation is Why it is useful in a server setting What drivers are