Does the MB use the CPU to generate beep codes?

On 27/04/2012 5:03 PM, Todd wrote:

Hi All,

Question: does the motherboard use the CPU to generate beep codes?

I think if the CPU itself is the problem, then there's no way for the
CPU to generate a beep code. So likely the beep codes are programmed
into the chipset instead.

Yousuf Khan

In message <4f9b116f$, Yousuf Khan
writes:

On 27/04/2012 5:03 PM, Todd wrote:

Hi All,

Question: does the motherboard use the CPU to generate beep codes?

I think if the CPU itself is the problem, then there's no way for the
CPU to generate a beep code. So likely the beep codes are programmed
into the chipset instead.

Yousuf Khan

Is there a beep code for CPU fault?

If it _isn't_ the CPU, what _is_ generating the codes? "Programmed into
the chipset" - something still has to _run_ that code.
J. P. Gilliver. UMRA: 1960/<1985 MB++G.5AL-IS-P--Ch++(p)+Sh0!:`)DNAf

a little bit of me still feels that some southerners think we northerners are
issued at birth with doomed kestrels. - Alison Graham, Radio Times,
3-9/11/2007.

Todd wrote:

Hi All,

Question: does the motherboard use the CPU to generate beep codes?

Many thanks,
-T

As far as I know, beep codes are programmed by the CPU. There are
some registers than need to be programmed. On the motherboards I
have here, if I connected the motherboard SPKR pins to the case
speaker, and just powered up the motherboard, there would be silence
if there was no CPU present.

There have been cases, where something like a short in a RAM module,
can prevent any beep codes from being emitted. Normally, you'd
expect a two beep or three beep error code for "bad RAM", but if
the RAM is bad enough to upset chipset power, it can stop the thing dead.
The BIOS code can run using CPU registers for temporary storage, while
the RAM is being set up. Otherwise, you wouldn't be able to bootstrap
the system, if there was a strict RAM dependency.

The reason the PC generates "one beep" on a good POST, is as a "speaker
test", the equivalent of a "lamp test" on other gear. That's to tell you
the speaker/beeper scheme is good, on each system startup. Then, if some day
you hear nothing, you're more likely to conclude the CPU has failed etc.

Systems can use more than just SPKR. Some Dells have four diagnostic LEDs,
to give a status code. There are motherboards with "Port 80 seven segment
LED display". And Asus used to have "Vocal POST", a Winbond chip capacitively
coupled into one side of the lime green audio output of the onboard sound,
and it would "tell" you what the error code was. The Vocal POST had
pretty poor fidelity, and all you could hear was mumbling, and then
you'd match the "cadence" of the sound you were hearing, to a list
of error messages listed in the manual. I still liked it as a feature,
but the design wasn't the best in terms of fidelity.

Paul

Paul wrote:

Todd wrote:

Hi All,

Question: does the motherboard use the CPU to generate beep codes?

Many thanks,
-T

As far as I know, beep codes are programmed by the CPU. There are
some registers than need to be programmed. On the motherboards I
have here, if I connected the motherboard SPKR pins to the case
speaker, and just powered up the motherboard, there would be silence
if there was no CPU present.

There have been cases, where something like a short in a RAM module,
can prevent any beep codes from being emitted. Normally, you'd
expect a two beep or three beep error code for "bad RAM", but if
the RAM is bad enough to upset chipset power, it can stop the thing dead.
The BIOS code can run using CPU registers for temporary storage, while
the RAM is being set up. Otherwise, you wouldn't be able to bootstrap
the system, if there was a strict RAM dependency.

Unless you mean some scratchpad RAM that is also present on the CPU chip,
I'm not sure I understand that: As far as I know, the CPU registers
themselves can only hold a byte, word, or double word, and thus are only
used for basic arithmetic or logic operations made during each instruction
cycle. In other words, there is not much "storage" there (in the CPU
registers themselves) to speak of, except for what a 16 bit or 32 bit
register itself can hold (which is only a single word or double word operand
or result or op code).

Bill in Co wrote:

Paul wrote:

Todd wrote:

Hi All,

Question: does the motherboard use the CPU to generate beep codes?

Many thanks,
-T

As far as I know, beep codes are programmed by the CPU. There are
some registers than need to be programmed. On the motherboards I
have here, if I connected the motherboard SPKR pins to the case
speaker, and just powered up the motherboard, there would be silence
if there was no CPU present.

There have been cases, where something like a short in a RAM module,
can prevent any beep codes from being emitted. Normally, you'd
expect a two beep or three beep error code for "bad RAM", but if
the RAM is bad enough to upset chipset power, it can stop the thing
dead. The BIOS code can run using CPU registers for temporary
storage, while the RAM is being set up. Otherwise, you wouldn't be
able to bootstrap the system, if there was a strict RAM dependency.

Unless you mean some scratchpad RAM that is also present on the CPU
chip, I'm not sure I understand that: As far as I know, the CPU
registers themselves can only hold a byte, word, or double word,

That's storage. It is very common to stash values into registers
temporarily. Don't know about now but at one time one CPU had an alternate
set of registers and one could swith back and forth at will. That was real
handy :)



dadiOH
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