From: pmonks AT iname DOT com (Peter Monks) Newsgroups: comp.os.msdos.djgpp Subject: Re: Questions about Allegro Date: Thu, 27 Feb 97 06:53:38 GMT Organization: Financial Market Software Consultants pty ltd Lines: 54 Message-ID: <5f3b1i$2gk_002@fmsc.com.au> References: <01bc2460$9a92bee0$8c081ecb AT sly> NNTP-Posting-Host: gw.fmsc.com.au Cache-Post-Path: clark.fmsc.com.au!unknown AT sleepy DOT fmsc DOT com DOT au To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp In article <01bc2460$9a92bee0$8c081ecb AT sly>, "Sly" wrote: >1. Why do the timer routines have to be installed in order to be able to >see the mouse on SVGA resolutions? AFAIK, graphics operations can't be performed from within the mouse event callback. Therefore Allegro merely updates some position variables in the callback, and then polls these variables and draws the cursor from within the timer interrupt. I'm not 100% sure, but I think this is the reason why. Someone please correct me if I'm mistaken. >2. What is happening when install_timer() is called, and Win95 complains >about the program should be run in MS-DOS mode? Cancel this requester and >the program looks like it is running normally, and any subsequent execution >of programs in that DOS box do not show this warning. Is the program >*really* running normally, or is something screwy going on in the >background? As of v2.2, when Allegro detects Windows it runs in a way that is more compatible. Win95 will probably still complain (since it doesn't like programs mucking about with the timer interrupt at all), but nothing screwy should be happening. The warning only appears the first time because Win95 recognises the program the subsequent times you run it, and doesn't bother asking again. I think that if you recompile the program, Win95 will ask again (unless you save the option into a PIF file). >3. I have read elsewhere that the timer should be reset to normal (ie. 18.2 >ticks/sec) before any disk access. Is this still necessary? Sorry, can't help you! :-) Anyone know the answer to this one? >4. Are the various ModeX screen modes restricted to use the first 256k of >video memory only? Or do I have to use the VESA modes to access the rest >of video memory? Yes and yes. Since ModeX only uses the standard VGA hardware (which can only access up to 256Kb of VRAM), only 256K of video memory is available. UniVBE provides low resolution VESA modes which give you all available memory, with the disadvantage that other VESA manufacturers don't usually provide these modes. Cheers, Peter ---------------------------------------------------------------------- Peter Monks http://www.geocities.com/Yosemite/4455/ pmonks AT iname DOT com pmo AT fmsc DOT com DOT au Peter_Monks AT australia DOT notes DOT pw DOT com