Re: [OT] Documentation for PC Architecture

[John Bradford]

> > I've done some tests with a simple kernel which I wrote: all that region 
> > (except video memory at 0xb8000) results "read only"...
>
> because it is usually designated as rom area, which naturally
> is read only ... 

On some boards I've seen, there is 384K onboard for ROM shadowing
purposes, and when only 128K is actually used, (as it is in a lot of
configurations), the other 256K is available as system memory.

However, this on-board 256K is only remapped when you have 8 MB RAM or
less on the board.  So with 8 MB the board reports 8448K of RAM, but
with 16 MB, it only reports 16384K.  In that case 256K of real RAM is,
indeed, lost.

John.
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