Opened 15 years ago

Closed 14 years ago

#3407 closed defect (fixed)

probable bug in real mode video BIOS => Fixed in SVN/3.1.4

Reported by: Ninho Owned by:
Component: other Version: VirtualBox 3.0.6
Keywords: video BIOS Cc:
Guest type: other Host type: Linux


Most probably a bug in the real mode video BIOS (int 10h).

Problem, as observed in plain MS-DOS - no ANSI.SYS or similar - running or other plain text mode programs with screen scrolling :

Normally while scrolling the screen up by one line, character attributes from the bottom line (usually line 25) are reinjected to the new bottom line which is "scrolled in". After 25 (or whichever # lines on screen) lines have been scrolled, all displayed lines will have the same attributes.

However using DOS in virtualbox, the lines inserted at screen bottom invariably come with default grey on black attribute (07) !

I have not investigated code used by (in the example) at instruction level, but since the 'right' behaviour I've been seing on all real machines (for almost 30 years!) and only virtualbox exhibits a difference, it has to be a bug in, most probably, the provided video BIOS.

Change History (7)

comment:1 by Ninho, 15 years ago

New comment : just checked the latest video Bios used by the Bochs distibution has the same bug (i.e. 'BIOS-bochs-latest'). Good old 'BIOS-bochs-legacy' is however correct.

Are you perhaps sharing that buggy code ?

comment:2 by Ninho, 14 years ago

(bump!) Just updated to Virtual Box 3.06 : it appears nothing has changed.

Can we hope for a revised BIOS anytime soon ? Is this bug assigned to somebody at least ?


comment:3 by Frank Mehnert, 14 years ago

Well, I can assign the bug to you... Contributions are always welcome.

comment:4 by Frank Mehnert, 14 years ago

Version: VirtualBox 2.1.2VirtualBox 3.0.6

comment:5 by Frank Mehnert, 14 years ago

Summary: probable bug in real mode video BIOSprobable bug in real mode video BIOS => Fixed in SVN/3.1.4

This bug will be finally fixed with the next VBox maintenance release.

comment:6 by Sander van Leeuwen, 14 years ago

Please check if 3.1.4 beta 1 solves the problem:

comment:7 by Frank Mehnert, 14 years ago

Resolution: fixed
Status: newclosed
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