Hi: I do not know whether this question is in the spirit of LQ but, in case somebody knows, here it goes: Suppose a PC is in a perfectly functional state. We unplug the RAM modules from the motherboard and turn on the machine. Can the BIOS make any beep?

I know. What's the aim of taking away the RAM. Well, its a purely theoretical question. If I were to construct a computer, I would make the self tests run as the very first thing. I suppose this can be done not using any more RAM than the CPU registers themselves. I don't know what happens when there is ROM shadowing. There should be a mechanism that shadows the ROM after the self-tests are done. All I know is that a system that invalidates diagnostics when the RAM is lacking would be pretty dumb.

Very open-ended question, like asking "how high is up?" If you write the BIOS, it'll beep whenever you tell it to.

An open-circuit on the memory slots would be a trivial test, and generating a beep for it is certainly possible, and if I remember correctly, is something I've seen before.

Thanks. OK. It can be done. But how did IBM did it. How does your PC, in case you have one, does it? Not how, I mean, does it beep or not?

Almost all mainboards do beep when the RAM is lacking. I found only a few that won't beep without RAM, for example the Biostar G31-M7 TE.

Thanks for your kind reply. I must confess my question had a practical side too, although knowledge was the first motivation. You'll see. Under circumstances I don't remember well, I turned on the machine and the RAM module instantly toasted. I could take it to the repair shop, but its a thing I generally dislike. According to your answer, which I trust, there is a problem with the motherboard.

The power source is fine. Measured with load, with an oscilloscope first and then voltmeter. As the module reached a high temperature, a high DC current must have passed through some track on the PCB, making it melt.

I'll make a test like this: put the oscilloscope probe into pins A0 or A1 of the BIOS. If the voltage remains constant during the first few seconds, then I'll know something is definitely wrong. Use of ROM-shadowing could complicate the scheme.

It's quite a pity, because this is the last machine I have with an ISA slot. Regards.

It should offer a beep code for no memory. That is one of the pre-post checks bios is supposed to look for.

Problem solved. In some motherboards, the BIOS won't beep if the CMOS battery is gone or too low. I measured, and read 1.085V in my voltmeter. But the nominal voltage for my motherboard is 3.0V. This revealed the mistery.

I have yet another machine which does not beep. I've just measured the battery and have found still lower. I'm beginning to have the strong suspicion that no motherboard will beep if the battery is low.

False. Most motherboards will beep even without the CMOS battery, and even more, they will boot the OS.

RAM shouldnt burn out that fast. Either it was already going 'bad', or else you were using RAM that wasnt suitable for your motherboard.

I'm bored with this topic

Yes, most motherboards will beep if the RAM is missing, defective or simply the wrong type.

Yes, most motherboards will beep regardless of whether or not the CMOS battery is charged.

Yes, different motherboards have different behaviors - including different beep codes.

Here's a good summary:

http://www.pantherproducts.co.uk/Art...BIOSbeep.shtml

I agree, through my experience in many fault computers (10yrs +).