Half Term 4 Flashcards
RAM, ROM and BIOS
What is BIOS?
Basic Input Output System is a program stored on ROM that runs when a computer is powered on and loads the OS
RAM, ROM and BIOS
What is POST?
Power On Self Test is a process run by BIOS that checks that all required hardware is present and working correctly
RAM, ROM and BIOS
What is UEFI?
Unified Extensible Firmware Interface is an alternative to BIOS that has now replaced it. UEFI provides faster boot times, better security, larger disk support and a GUI
RAM, ROM and BIOS
How does booting up a computer work?
- A ‘reset’ command is sent to the CPU
- The CPU locates and starts the BIOS start-up program
- POST checks that all hardware is working correctly
- Video card is initialised and the screen starts working
- BIOS searches for a ‘bootable’ drive to start up the OS
- The computer reads the ‘boot sector’ of the drive and the instructions are executed
- On a hard drive, the ‘boot sector’ contains the Master Boot Record
- The MBR points the BIOS to the ‘primary partition’ on the hard disk
- The ‘primary partition’ contains the OS
- The code on the ‘boot loader’ (the boot sector of the primary partition) is executed
- The OS is loaded into memory
- The boot script/boot file runs and loads settings configurations
RAM, ROM and BIOS
What does ‘random access’ mean?
Any storage location can be accessed directly
RAM, ROM and BIOS
What is virtual memory?
An area of secondary storage used by the OS as RAM. The operating system’s memory manager uses secondary storage such as the hard disk or flash drives as RAM. Pages/segments that have not been used recently are moved out of RAM to virtual memory. In the example above, if the user wanted to use program F (currently not in RAM), existing page(s) which are not being used are moved from physical RAM to virtual memory to make space.
RAM, ROM and BIOS
What is EEPROM?
Electrically Erasable Programmable Read Only Memory is the type of ROM that stores BIOS and UEFI
RAM, ROM and BIOS
What is DRAM?
Dynamic RAM is used for main memory
RAM, ROM and BIOS
