NOLFB (VESA 2.0 patch)

for Windows NT/2000/XP
by Ken Silverman

Tired of 320x200? With NOLFB you can play in hi-res again.
A newer faster computer that comes with Windows XP means a lot of old programs that used to work on Windows 98 won't work anymore. When DOS programs initialize the VESA 2.0 linear framebuffer mode, one of the steps (after the screen mode is set) is using DPMI function call (ax=0x800) to map video memory into a linear space.

Under WinNT/2K/XP, this call always fails. Programs will exit to DOS with "DPMI_mapPhysicalToLinear() failed!" error message. Unfortunately, the screen is usually black or jumbled at this point, so to most people, it looks like a crash.

Here's a workaround:

[1351 bytes] A TSR that patches the VESA driver by fooling DOS programs into thinking the VESA 2.0 linear framebuffer modes aren't supported. Source code is included.

You must run this program at the command prompt. Extract NOLFB.COM into your game's folder as your game and launch NOLFB and then your game both from the command prompt. After you are through, type: "EXIT" at the command prompt


  1. NOLFB will only fix DOS VESA 2.0 applications that have a fallback code that supports the segmented video modes (from VESA 1.2). If the application does not run in segmented video mode, then it will exit with a visible error message instead of a black or jumbled screen.

  2. NOLFB does not add any new VESA modes to your computer! In fact it does just the opposite. If your graphics adapter does not support standard VESA modes (such as 640x480x8) in any DOS application, then this patch will not help you.

  3. Some newer video chipsets (most notably those based on the GeForce4 series) do not support VESA with resolutions above 640x480 under Windows NT/2K/XP. I believe this is due to a conflict between the VESA driver and the operating system and not NOLFB. If your monitor goes into a standby/power-off mode, and you are using a resolution above 640x480, please remember to also try 640x480 mode!

  4. Here's a list of programs I've tested that are fixed by this patch (assuming the above conditions are true): Duke Nukem 3D, Shadow Warrior, most of the Build engine tools, 2Draw, and some demos on my website that are linked to my DOS VESA code: "VES2.H".

  5. NOLFB will not do much in Win95/98/ME other than cause the framerates to decrease in games. Use at your own risk!


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