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DOS开发编程 & 发展交流（开发室） » How to access a 32-bit address space under DOS?

Floor1　luyd	Posted 2003-04-28 00:00
初级用户　Posts 2　Credits 109
I've recently been making a PCI card, and the BIOS maps it to a space with Baseaddress 40400000. How can I access (read/write) this block of memory under DOS? I'm using BC31, what should I do? Experts, save me!

Floor2　如是大师	Posted 2003-04-28 00:00
元老会员　Posts 3,351　Credits 9,654　From 湖北
I don't really understand it, let's wait for wengier to have a look. Just helping you bump the thread.

Floor3　Wengier	Posted 2003-04-29 00:00
系统支持　Posts 10,521　Credits 27,736
About this, it's best to use assembly for addressing. Using BC may not be very convenient, though I haven't used it either.

Floor4　Dark-Destroy	Posted 2003-04-29 00:00
元老会员　Posts 3,551　Credits 8,312
Let me ask, what exactly does assembly mean??

Floor5　luyd	Posted 2003-04-29 00:00
初级用户　Posts 2　Credits 109
Many thanks to all the seniors, please hurry and teach me a few tricks, I'm almost going crazy from the urgency.

Floor6　ATLaS	Posted 2003-07-09 00:00
初级用户　Posts 29　Credits 169
In real mode, it's impossible to access that address space. Under bc31, it seems there should also be some kind of 32-bit dpmi host or something similar, so that the program runs in 32-bit protected mode; then the memory address mapping is in flat mode. Just directly define a far pointer pointing to that address, and you can access it. I've done it under watcom c+dos4g/w, but under bc I'm not sure.

Floor7　Dark-Destroy	Posted 2003-07-10 00:00
元老会员　Posts 3,551　Credits 8,312
Using djgpp works too~ djgpp has cwsdpmi~

Floor8　feng	Posted 2003-09-10 00:00
初级用户　Posts 5　Credits 117
I've run into exactly the same problem too. I don't know whether you got your problem solved or not. If you did, could you tell me? If not, we can discuss it together. My email is [email protected]

Floor9　ldy810	Posted 2005-10-07 22:05
新手上路　Posts 6　Credits 13
You can first turn off GATE A20, then call 1M less memory, but at most you can only access 4G

Floor10　taowentao	Posted 2005-10-08 16:03
高级用户　Posts 111　Credits 739　From 辽宁沈阳
Its linear address is 40400000 >> 12 + 0000 = 40400, which is within 1M, so real mode can access it completely.

Floor11　jhbin_1999	Posted 2005-10-09 22:36
初级用户　Posts 4　Credits 117
I've run into the same problem too, and would like to discuss it with you. email: [email protected] qq:55512153