Click here for more background to the phrase "Booting" a Computer.
First, a definition of Firmware
From https://www.howtogeek.com /210186/what-is-the-difference-between-bios-and-firmware/
Firmware is a combination of persistent memory, program code, and the data stored in it. Typical examples of devices containing Firmware are embedded systems such as traffic lights, consumer appliances, digital watches, computers, computer peripherals, mobile phones, and digital cameras. The Firmware contained in these devices provides the control program for the device.
BIOS (Basic Input/Output System) is also known as System BIOS, ROM BIOS, or PC BIOS firmware. This chip was built into the motherboard of the first IBM PC (and IBM PC compatibles) as their diagnostic testing sequence or POST (Power-On Self-Test). User settings for the PC were stored in CMOS memory, powered by a small battery. The name originated from 1975 as the Basic Input/Output System used by the CP/M operating system.
Click here for a listing of the original
UEFI (Unified Extensible Firmware Interface) These days, since about 2012 in particular, new computer motherboards designed by Intel have a UEFI chip. Unlike the now legacy BIOS which looked for an MBR (Master Boot Record) on the hard drive, the UEFI chip looks for an EFI file stored on a partition in its place. Thus they both share the same core purpose: preparing the system to boot into the operating system. And many people still call the UEFI chip the BIOS because of the familiarity of the term.
Please note too that computer peripherals will of course contain other Firmware besides BIOS/UEFI/EFI. Network cards, video cards, raid controllers, hard-drives, flash drives, SSDs, and sound cards (just to name a few) can all have Firmware (RAM and registers) embedded inside.
On power startup, BIOS firmware on the motherboard does initial hardware checking, then loads ("boots") the Operating System and low level drivers from the hard drive, associating each driver with at least one interrupt service routine (or handler). The Operating System provides a unified approach to the main memory on the motherboard.
Read following steps 1,2,3,4 as Low to High. 4,3,2,1 High to Low.
A bit of history. With SW software, Windows 32-bit NTVDM.exe executable ran inside CSRSS for years supplying a stable interface for SWCS software, minimal graphics, but maximum text-based data enquiry, audit trails and reports input and output.
Run dxdiag.exe from a command line prompt in Windows to see the details of all video and audio hardware installed.
Run msinfo32.exe to see its BIOS version. If it shows BIOS MODE: UEFI, then it's running UEFI.
The SMBIOS (System Management BIOS) version number has been loosely related to the Windows version the hardware is most likely to ship with.
Click here for the Wikipedia article on its early history, derived from the IBM PC Compatible BIOS developed in a Clean Room by Phoenix Technologies in May 1984.
If you've used PCs long enough, you know the frustration of trying to get to the BIOS screen so you can adjust settings like the order of boot devices. Every PC has a different magic keystroke, which must be pressed at exactly the right time.
On modern UEFI-equipped devices running Windows 10, the task is much simpler. Open Settings > Update & security > Recovery and then, under the Advanced Startup heading, click Restart now. (You have to be signed in as an administrator, naturally.)
That restarts your PC to a special startup menu. Click Troubleshoot, then click Advanced options to get to the screen which includes the UEFI Firmware Settings option.
Other advanced options on this screen let you roll back a problem with System Restore or change startup settings. If you're looking for good old Safe Mode, you'll find it under the Startup Settings menu.
If going through Settings seems too complicated, there's an even faster shortcut. From the Windows desktop, click Start, click Power, and then hold down Shift as you click Restart.
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