minimum components to see POST

[hatimh]

I'm just wondering what you need in terms of PC components attached to the motherboard in order to at least see something on the screen, eg. memory count.

Cheers.

-----------------------------------
Don't extract the urine.

 

[Bames_Jond]

The minimum components are as follows:

PSU
Motherboard
Memory
CPU (and cooler)
Graphics adapter if it's not onboard.

You might want to attach a keyboard also although you should see the system running POST without it.

Some years ago it was not necessary to have memory onboard your motherboard to see the POST. Today all motherboards require some memory onboard to POST.

My name is Jond, Bames Jond.

My ACPI incompatible network adapter killed my SB Live!

 

[Kidane]

Are you sure about that with the memory? How gay. I mean, isn't 640k enough for anyone? Seriously though, does I need my 512MB of extended memory to get into the BIOS? And maybe someone who is a computer guru could answer this:

Why on earth don't they change the architecture to accomidate more than 640k base memory? And this 640k, is it on the motherboard or is it allocated from the normal DIMM, RIMM, SIMM, etc. before EMS/XMS?

Kidane

 

[jlanka]

the 640K base is all software (OS). The hardware doesn't care how much or how little you have. DOS/95/98 does. NT/2K and XP don't use that old DOS model any more.

<i>It's always the one thing you never suspected.</i>

 

[Jake75]

I thought it was a hardware limitation, back in the old days when they thought no one would ever need more than 640K...
I mean, if it is OS related why does the 640KB show up in POST anyway?

Well, you live and learn...


MONDAY

 

[Bames_Jond]

If the computer system developers could just remove the 640 KB. base memory i'm sure they would have done that a long time ago! The problem is more defficult than you would think and I can't explain it, because I do not know the answer too why the 640 KB just can't be removed...

The 640 KB. base memory is mounted on the motherboard.

My name is Jond, Bames Jond.

My ACPI incompatible network adapter killed my SB Live!

 

[jlanka]

thats gotta be an older MB...

Back in the old days they used to show you the "640K + XXX expanded" just to make DOS users feel warm and fuzzy. Didn't have anything to do with anything except that.

<i>It's always the one thing you never suspected.</i>

 

[girish]

the 640kb limit was of the hardware, software was written around it.

the 8086 processor that was used in the first PC by IBM, supported only 1 MB of memory, and that was divided as follows:

0-640k: User memory, but first 1k used for teh IVT (Interrupt Vector table as the processor was designed to use this region to store addresses of the 256 (4 bytes each) interrupts in the lowest 1k)
-128k: Video memory, used in parts by different displays, some by the MDA (Monochrome Display Adapter), the CGI (Colour Graphics Adapter) an EGA/VGA (Video Graphics Array/Adapter)
-128k: User ROM-BIOS, like the one we find on a display card, system BIOS can be augmented with custom BIOS mapped in this region.
-128k: System ROM-BIOS, the processor was designed to start with the first instruction 15 bytes short of 1 MB, so all the firmware had to be placed there.

640kb was more than enough for DOS programs and most of the shell programs that had a GUI (although in text mode)

Windows changed it all.

So, early days, there was no concept of chipsets, individual functions were carried out by specialised chips, and the basic memory (128/256k) was present on the board itself. there was no concept of a memory module either, the board had arrays of DIP sockets to get the chips, and additional memory was installed by way of ISA (8 bit wide then!) memory upgrade cards!!!

These days, even the 640k base memory is present in the DIMM, nothing is present on the board, so if you have a newer board you need to put some memory on it to get it boot. But it is a common diagnostic trick to remove the memory and the display card to check the board. If it starts beeping continuously in absence of memory, it is good. Else how would the BIOS code to make the beeps have executed!!???

girish

<font color=red>Nothing is fool-proof. Fools are Ingenious!</font color=red>