dcr0801%ritcv@cs.rit.edu (12/14/89)
I am currently writing my own little *nix type OS on a IBM type machine. The hardware has 1 meg. on the system board, and 512k in an expansion I/O slot. Currently running the processor in 286 mode, any descriptor table entries where the base address is over the 1 meg boundry gets truncated to the lower meg. This gives me only 640k of usable memory. I am sure (99%) that my tables entries are correct, yet I still can't access the 'expanded' memory. Is there some kind of bit somewhere that enables the processor to generate address over 20 bits on the address bus?? I could only guess that DOS (yeck!) does something to map higher memory into lower memory so that it could be access in real mode. I know that there must be a way to be able to just generate the 24 bit address and get the memory without mapping it, but, like I said, I haven't found the 'Golden Bit' yet. If anyone out there in net.land could give me a little hint on this, it would be GREATLY apprieciated!! Thanks in Advance, Dave Rein (dcr0801%ucss@cs.rit.edu) or (..!uunet.uu.net!ultb.cs.rit.edu!ritcv!dcr0801) [Sorry, no cute byeline at the moment. Hard to be funny and frustrated!!]