Re: SNAP and 1920x1200 resolution...
- From: "Andi B." <andi.b@xxxxxxx>
- Date: Thu, 26 Feb 2009 20:03:44 +0100
James J. Weinkam schrieb:
Marty wrote:Sometimes DOS do not work with ACPI cause ACPI uses APIC to enable high IRQs which DOS can not handle. Using ACPI with /PIC solves this problem here.James J. Weinkam wrote:The fact that the windowed session works fine after going through these maneuvers shows that there is nothing fundamentally wrong with the video device or its drivers; rather there must be some sort of configuration problem in the windowed DOS object or a bug in the code that launches windowed DOS and WINOS2 sessions. Once the windowed session is working, the DOS settings that can be examined and changed dynamically are still the same as those of the DOS window object.
My guess would be that the video BIOS starts up the video hardware in a really weird mode. OS/2 will call the BIOS routine and emulate as many functions and modes as it supports in VSVGA.SYS when you start the DOS session. If during this process, an unsupported video mode or video BIOS call is used, OS/2 will halt the DOS session until you switch to full screen mode. When you do, the video BIOS is free to run on real hardware, and probably transitions through this unsupported mode back into the standard 80x25 text mode. Once you reach this standard mode, it's ok to switch back to windowed mode because OS/2 can support it.
I don't see why this should be a problem. As I understand it, there is a component of OS/2 called a virtual DOS machine that emulates a standalone PC running some version of DOS. It is reenterable allowing several DOS sessions to run simultaneously. Each VDM instance can be in either fullscreen or windowed mode. It seems to me that it would be instances running in fullscreen mode that would get into trouble trying to deal directly with the latest hardware, while the windowed sessions would only have problems if other OS/2 VIO sessions also had similar trouble since the emulator displays in the window using the same standard os/2 API calls that other VIO sessions use. Is this true or am I missing something?Can't tell because in fullscreen mode the CPU meter doesn't appear. However, investigation revealed that that was the reason for the slow switch from fullscreen to windowed. I forgot to set idle seconds and idle sensitivity after installing RC6a. I hadn't noticed until now since I normally launch the few DOS applications that I still use from ZTree using startd, and idle seconds and idle sensitivity are properly set for those sessions from startd's DOS.INI file. For the current round of experiments I was clicking on the objects in the command prompts folder which I don't normally do.
A similar thing happens when you play some old DOS games which do some strange programming directly to the video hardware, or some SVGA games. The unusual thing here is that the strange mode is encountered before you even get out of the initial base video handler.
Additional experiments revealed that the time it takes to switch from fullscreen to windowed using Alt-Home varies depending on what else is on the desktop at the time. If there is nothing else on the desktop or only open folders, the switch is virtually instantaneous; however if there are any open sessions, even minimized, then the switch requires about 10 seconds.
Is your CPU pegged during this time? Is the DOS window itself constantly consuming CPU time? It sounds like your DOS priority and idle sensitivity settings may need to be adjusted.
Andi
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