And I'm just answering his question. Don't understand what this "brake" thing is about ... <someone step in front of a car ? >. Just using this as an example of how the choice of words (Break vs Brake) can throw the reader off.
Whether it is new UEFI boot instructions or the old style BIOS, you still don't install an OS "into the BIOS". If readers are having trouble understanding what is being asked, it's very difficult to provide a useful answer. If this is the OPs assumption, we have thinbgs to adress before those other questions can be answered. So the 1st thing required is concentrate on what does matter... using commonly understood hardware definitions so that potential helpers reading the question will understand what is being asked. Then, clear and accurate answers can be provided.
There are two basic / common ways for a single user consumer to *install* the OS:
1. Using Optical w. install DVD - The reason you only find tutorials for UIEFI and not DVD is that installing from a DVD, the instructions are:
a. Stick DVD in optical drive
b. Start machine
c. Follow instructions
That's it .... on a new build you shouldn't have to do anything besides plug everything in , turn on the machine and insert the disk. It is extremely rare that you ever have to touch or look at the BIOS to install an OS. Most often you only need to go in and change the boot order when
reinstalling because after it was installed the 1st time, someone changed the default order from Optical to disk drive (or SSD). Of the disk is empty, it will go to the DVD after finding nothing on the empty HD.
That's why I didn't quite understand your search for installing OS "in non UEFI BIOS mode" since its just "Installing Windows from DVD" and it installs itself.
2. UEFI - The Unified Extensible Firmware Interface is simply a standard programming interface for booting a computer. UEFI was designed
to replace the BIOS but is also compatible with older BIOS-based machines. This type of install requires instruction sets to be stored in a folder in flash memory on the motherboard or on the hard drive (or even network drive). BIOS routines are stored in firmware not on a disk.
Getting back to the OP, I can only guess about intent but there were several ways one could interpret this post. By being budget restricted, was there an assumption that a "disk drive" wasn't needed ? And that the BIOS would somehow hold the OS ? Do a web search on "Disk Drive" and see what you get. My 1st hit was:
https://en.wikipedia.org/wiki/Hard_disk_drive
My thought was that perhaps in reading forum posts where peeps said they weren't going to install an optical drive and do a USB install, it had somehow been misinterpreted that a "disk drive" (SSD or HD) wasn't needed. On the other hand, perhaps the need for a HD was understood but OP just mistyped and wrote "disk dive" instead of "Optical drive" and fully realizes that using USB allows for skipping an "Optical drive".
So we were left with .... If there was no "disk drive" (or SSD) , the install is not taking place; if there is no optical drive, then the tutorial provided on the eight forums site gives detailed instructions on how to do so.
The other post explained his other question of how to obtain product keys.