Memory Map x86

[nosedays]

Hey guys,

I've got a question concerning the "Memory Map x86" article in the wiki. Does anyone know what the source for the low memory map is? I suppose how your low memory is organized depends on your BIOS, is there any way to find out how my own low memory map looks like? Or is there maybe some kind of standard?

[mathematician]

The memory map for the first megabyte of memory has been fixed almost since the beginning of time. Basically, it is safe to use anything above 0x500, and below 0x90000

[nosedays]

Hey, thanks for the answer. But is that some sort of convention people just follow? Or is there any standard where it is written down? Also, have you got any idea considering my other questions?

[mathematician]

Hey, thanks for the answer. But is that some sort of convention people just follow? Or is there any standard where it is written down? Also, have you got any idea considering my other questions?

It was determined more or less by the hardware designers of the original PC. The first kilobyte was the interrupt vector table, above that was the bios data area; video memory began at 0xb0000, and above that was the bios code beginning at 0xf0000. A few years later the EGA/VGA arrived to take care of memory between 0xA0000 and 0xB0000. Later still there was the extended bios data area occupying memory above 0x90000.

I don't even know what your other questions are.

[nosedays]

Nevermind, that's basically it. Thanks alot.