dosbox-x/BUGS/VGA emulation errors.txt
Jonathan Campbell 20c1366cb4 update BUGS file
2015-02-05 06:57:55 -08:00

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VGA BUG: Color palette error, last color of the palette, usually if it's white,
instead usually comes out black.
- Surprise! productions, The Good, The Bad, & The Ugly
- Happens at the demo part with the gargoyle demon art thing that warps
vertially: the failure appears as black splotches on his wings that SHOULD
be white.
NOTE: I'm not certain but I wonder if it has anything to do with the
previous demo effect and possible palette animation involved for
the "fading" effect as it renders. If I'm right, then whether or
not the error happens depends entirely on when the previous demo
effect ended and the state the color palette was left in.
================================================================================
THE FOLLOWING BUGS ARE FIXED!
================================================================================
VGA BUG: Exotic VRAM clearing tricks do not work, leaving "garbage" on the screen
- Abaddon: Cycling!
- Failure to clear the screen is visible when the VGA split-screen pans upward.
The "loading" graphic and other garbage contents are visible below the
animated VU meters where on real hardware that part of the screen would be
blank.
NOTE: This is still a problem with machine=svga_s3, but fixable by setting
machine=svga_et4000 instead. I'm not sure at this time whether the
demo has the same problems on real hardware or not.
- Surprise! productions, The Good, The Bad, & The Ugly
- There are two parts with rotating wireframe meshes that make use of VGA
palette trickry to create "motion blur". Failure to clear the screen results
in a wireframe mesh with a border of garbage pixels that flicker.
- Optic Nerve (demo)
- At the start of each demo part, when displaying the title of that part, the
demo fails to clear the screen. Result: demo title with contents of the
previous screen or title screen around it, garbled due to palette mismatch.
NOTE: This is still an issue with machine=svga_s3, but you can
eliminate the problem by setting machine=svga_et4000 or running
the demo from an MS-DOS 5.0 or 6.0 bootdisk. MS-DOS 6.22 may cause
stability issues. Windows 95/98 DOS mode is certain to cause the
demo to crash.
- Impact Studios: Legend
- Failure to clear the screen causes 3D dot fields to overdraw into an orange
flickering ball.
VGA BUG: Failure to save and restore VGA text screen contents
- Microsoft Windows 95 boot logo
- Windows 95 is able to show the boot logo, but when restoring the VGA text
console, the contents are all messed up. Why?
- Microsoft Windows 3.0/3.1/95/98
- Running the DOS prompt in a window works, until you move the mouse cursor
over or near the DOS window. If you go back to fullscreen, the extended
character set is missing. If you go back and forth 2 or more times, the
character font is missing entirely.
- If any DOS program writes to the screen the contents appear as garbage at
the top of the Windows desktop. Whatever normally prevents the DOS program
from affecting the screen by Windows is not triggering in DOSBox and it
may be the source of corrupted VGA states.
- Weird crashes when you move the mouse cursor over the window do NOT happen
in Windows 3.11 Windows for Workgroups if 32-bit disk and file access is
enabled.
VGA BUG: Switching to the DOSBox keymapper, then back, results in failure to redraw
emulated VGA output.
VGA BUG: Active display area cuts off right margin for Do Whacka Do
- Do Whacka Do works perfectly except that the rightmost 8-10 pixels are cut off,
which makes it a bit difficult to read the scroller at the bottom of the screen.