System Software
Start Up and Boot Software
- Hardware needs to be checked on boot up
- If correct, operating system and hardware drivers are loaded in RAM
- A boot sequence is the initial set of operations that the computer performs when it is
switched on
- Boot/bootstrap loader is the program that performs the boot sequence
BIOS
- BIOS (basic input-output sequence)
- Low-level software
- Resides in non-volatile ROM chip
- Firmware: permanently resides on ROM
- Process when computer switches on:
● BIOS begins the POST (Power-On Self-Test) to check hardware
● Inventory of hardware obtained from CMOS (Complementary Metal-Oxide-
Semiconductor)
● Hardware is tested
● BIOS locates MBR (Master boot record), a section of code on hard drive
responsible for loading and executing the operating system kernel, and
continues startup procedure
Kernel
- Core of operating system in RAM
- Translates input/output from software into instructions for CPU
- Handles memory and peripherals eg. keyboards, monitors, printers and speakers
CMOS
- Battery backed volatile memory (as different hardware can be installed and user
settings can change)
- Stores hardware details (types installed such as disk drive) and user settings (current
date and time)
- Referred to by BIOS in boot up process
, UEFI
- UEFI (Unified Extended Firmware Interface)
- More efficient start up process in terms of functionality and speed
- Firmware
- NOT POSSIBLE to switch from BIOS to UEFI: needs new hardware that supports it
- Backwards compatible with operating systems expecting BIOS
- Advantages:
● Can boot from drives 2.2 TB or larger
● Can run in either 32-bit or 64-bit mode
● More user-friendly setup screens (eg. graphics and mouse cursor support)
● Supports secure boot (checks operating system for malware)
● Supports networking features to aid in remote troubleshooting and
configuration
● Tiny operating system that runs on top of computer’s firmware - can do a lot
more that BIOS
● Stored on: flash memory, motherboard, hard drive, or shared on a network at
boot
Start Up and Boot Software
- Hardware needs to be checked on boot up
- If correct, operating system and hardware drivers are loaded in RAM
- A boot sequence is the initial set of operations that the computer performs when it is
switched on
- Boot/bootstrap loader is the program that performs the boot sequence
BIOS
- BIOS (basic input-output sequence)
- Low-level software
- Resides in non-volatile ROM chip
- Firmware: permanently resides on ROM
- Process when computer switches on:
● BIOS begins the POST (Power-On Self-Test) to check hardware
● Inventory of hardware obtained from CMOS (Complementary Metal-Oxide-
Semiconductor)
● Hardware is tested
● BIOS locates MBR (Master boot record), a section of code on hard drive
responsible for loading and executing the operating system kernel, and
continues startup procedure
Kernel
- Core of operating system in RAM
- Translates input/output from software into instructions for CPU
- Handles memory and peripherals eg. keyboards, monitors, printers and speakers
CMOS
- Battery backed volatile memory (as different hardware can be installed and user
settings can change)
- Stores hardware details (types installed such as disk drive) and user settings (current
date and time)
- Referred to by BIOS in boot up process
, UEFI
- UEFI (Unified Extended Firmware Interface)
- More efficient start up process in terms of functionality and speed
- Firmware
- NOT POSSIBLE to switch from BIOS to UEFI: needs new hardware that supports it
- Backwards compatible with operating systems expecting BIOS
- Advantages:
● Can boot from drives 2.2 TB or larger
● Can run in either 32-bit or 64-bit mode
● More user-friendly setup screens (eg. graphics and mouse cursor support)
● Supports secure boot (checks operating system for malware)
● Supports networking features to aid in remote troubleshooting and
configuration
● Tiny operating system that runs on top of computer’s firmware - can do a lot
more that BIOS
● Stored on: flash memory, motherboard, hard drive, or shared on a network at
boot
