can not edit B800:0000 in pure dos
1 Attachment(s)
Hello folks,
I write the below sample program named "h1.asm"? Code:
assume cs:code 2. In Ubuntu 10.04 + dosemu 1.4.0.1, run the program in two ways: a. If exec dosemu in command line as "$dosemu -dumb", yes, it's in shell mode. and then use debug to check, "B800:0000" can be modified as expected. Code:
"Welcome to dosemu 1.4.0.1!" b. If exec dosemu in command line as "$dosemu", and run the program again, the symptom is as same as 1.(pls see attachment picture). 3. In Windows, I replace "mov ax,0B800H" to "mov ax,2000H" and try again, it would be edited well. So I wonder if it is coursed by "B800" segment address. All above make me confused, would you give me any suggestion? Thanks in advanced, Phillip |
Update by myself.
I try to run the program directly in dos mode, Code:
D:\masm>h1.exe Perhaps it is caused by debug.exe(16bit mode)? |
Sorry, but your English leaves me wondering as to what you want, could you try a *bit* harder? :)
You're trying to write to the video buffer in text mode, right? Well, according to your 2nd post, you've succeeded...? If not, then what are exactly are you trying to DO? |
Hi resetreset, thanks for your reply. My question is, when run the program in "debug" mode, I can not write the expected data into video buffer "B8000-BFFFF". While I can get success by run the program in command line directly(After run as command line, and use debug to check later, the video buffer data is modified as expected).
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Oh,.... :) I would rather suspect that Debug takes OVER the whole screen, so that a write to video RAM would be pointless. Exactly HOW it does it, I don't know, it's been a while since I dabbled in stuff like this - this *should* teach you about the perils of using Microsoft software :)
If you're talking about using debug to SINGLE-STEP through a program, well, I think it's virtually impossible to keep your "a" on screen while it does so - the amount of stuff that happens is probably just too much. May I ask what you're dabbling IN, that you want to do all this stuff, in this day and age? If you're interested in old school gfx programming, may I take this opportunity to tell you and hopefully recruit you into the demoscene? :) : en.wikipedia.org/wiki/Demoscene Tell me what you thought of it, I'd love to make a new friend with similar interests as mine :) |
Hello resetreset,
I google for my question, and think that it is caused by "debug.exe" would keep current environment so that it will not display 'a' as expect while run it directly in command line can do. My favor is Perl. Though Assemble language is old, I study it in order to know computer system deeply, what happened in underlying system. Thanks for your kindly introduction, Demoscene is very cool! I will try to draw some in future days, :) Phillip |
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