IBM PC Boot sequence

[shaunywhite]

Could you please clarify something for us. We are having a little argument on the exact IBM PC boot sequence from powering on the system from cold. When exactly does the BEEP occur. I was under the impression that it was a POST confirmation BEEP, one of my colleagues says different in that the POST BEEP occurs as soon as the mainboard receives power!

[YODA74]

the computer has to meet nessessary system requirements before booting up.
if it fails post THEN it returns a beep indicating what is wrong.I believe all computers are a little different, mine does not even beep when you turn it on? If it beeped the second the mother board received power I would think that would defeit the purpose of the post??

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[mjc]

Some boards (alot actually) beep once at the beginning of the tests...it is actually a test itself...to see if the PC speaker is working. If the speaker wasn't working then all the beep codes in the world would do no good.

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

[Paleo Pete]

In most cases, the beep is after POST, or Power On Self Test, and it means that BIOS information has been read and matches the system configuration.

As mjc said, some motherboards will use a beep to test the speaker, and some do not beep at all. These are very few, most do sound one beep to let you know the system is "happy". It will be after POST, not the instant power is turned on.

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[bassman]

Just in case someone is unfamiliar with what POST means, it is Power On Self Test. It is a series of different "checks" before it can load OS.
The very first thing it does is send power and wait for feedback, along the system bus and address bus. This is the comunication path to and from the cpu and RAM. Without this NOTHING works. Once power and presents is established, then the RAM count begins. After that, a check for and of other internal devices along with whatever external devices are attached to them (USB, serial,etc...)
SO, your first BEEP should come once it has established that there is infact RAM there to count. Try pulling your RAM out and booting to see how fast you get a series of long beeps http://www.PCGuide.com/ubb/wink.gif (please don't try this at home, for skilled proffesionals only) http://www.PCGuide.com/ubb/tongue.gif
If you get a splash screen during the POST, you can hit ESC. as soon as it comes up and SEE what is happening.
How much was this bet anyway??? http://www.PCGuide.com/ubb/biggrin.gif

EDIT: OK Pete beat me to some of that.

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If I tell you to think for yourself, then you're not doing it.
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This is not directed at those asking questions in order to gain knowledge. That shows you are thinking.

[This message has been edited by bassman (edited 10-02-2001).]