problems with memory-mapped I/O

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September 15th, 2004, 02:33 PM

kpseymour

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problems with memory-mapped I/O

I'm not sure this is the correct forum but I couldn't find one for DOS or assembly language.

After some research I can read and write data words and bytes from some custom board's I/O-mapped I/O using DOS 6.22 (because I have to) and assembly code written using TASM and TLINK.

A third board has some dual ported ram (dpram) that is supposed to be memory-mapped I/O started at base address D4000h with an offset of 1140h. My single board computer (sbc) has a 486-DX2 and has a PC/104 bus that all of the boards connect to.

I can't seem to write to the memory-mapped dpram.

I am starting to believe that I need to somehow reserve the memory in DOS. But I'm not sure.

Any ideas?

Thank you,
Keith P. Seymour

September 15th, 2004, 03:21 PM

edwinbrains

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Quote:

Originally Posted by kpseymour

I'm not sure this is the correct forum but I couldn't find one for DOS or assembly language.

Although I don't think we have one of those forums, cross-posting doesn't help either. I've deleted the other thread.

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