Messages in this thread | | | Date | Tue, 19 Aug 2003 08:37:31 +0100 | From | John Bradford <> | Subject | Re: [OT] Documentation for PC Architecture |
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> > 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.
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