Boot Process, [] PCs

Whatever else the boot process involves, what is most important is what you see it do, especially on the screen. I will limit details to what to expect physically.

.. boot up ..

The boot process is performed by the mother board's BIOS chips, a set of one or two chips, somewhat on the large size, perhaps with 28 pins each. These are almost always identified with a manufacturer's name, like "American Megatrends" or "Phoenix."

Different users have distinct preferences for one name brand over another, especially since early boards (through the late 80's) often included wacky BIOS chips. (My BIOS gets the date wrong since the beginning of 2000.)

The BIOS chip is replaceable (although I have never heard of anyone ever getting a replacement), because -- supposedly -- a BIOS manufacturer can't guess what type of processor you might install in the future.

The whole purpose of the boot-up process, called the "Power On System Test" (POST), is to ascertain what is attached to the mother board, that is, how much memory, if there is a video card, a keyboard, what the hard drive and floppy drive specifications are. After all, while the computer was asleep, the user could have made changes.

The POST program is thus hardwired into the BIOS chips, and only starts up (that is, it is run by the CPU) when the CPU senses that power has been turned on.

In addition, the BIOS POST process tests everything, although you can set things up to not test certain components, or set instructions not to warn you. More on that below.

One of the first things the BIOS does during a boot-up is to check for the existence of a video card, and start it up. Without a working video, the BIOS cannot tell you much of anything.

What the BIOS's POST program cannot do is to guess what file system or OS may be on board. Thus the POST stops once it has found the boot sector of the boot device.

.. what happens ..

OK, follow this sequence...

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