Specifications
906
Chapter 15 Video Hardware
Table 15.12 Continued
Color Memory
Resolution Depth Max. Colors Required Memory Used
1024×768 16-bit 65,536 2MB 1,572,864 bytes
1024×768 24-bit 16,777,216 4MB 2,359,296 bytes
1024×768 32-bit 4,294,967,296 4MB 3,145,728 bytes
1280×1024 16-bit 65,536 4MB 2,621,440 bytes
1280×1024 24-bit 16,777,216 4MB 3,932,160 bytes
1280×1024 32-bit 4,294,967,296 8MB 5,242,880 bytes
1400×1050 16-bit 65,536 4MB 2,940,000 bytes
1400×1050 24-bit 16,777,216 8MB 4,410,000 bytes
1400×1050 32-bit 4,294,967,296 8MB 5,880,000 bytes
1600×1200 16-bit 65,536 4MB 3,840,000 bytes
1600×1200 24-bit 16,777,216 8MB 5,760,000 bytes
1600×1200 32-bit 4,294,967,296 8MB 7,680,000 bytes
From this table, you can see that a video adapter with 4MB can display 65,536 colors in 1600×1200
resolution mode, but for a true color (16.8 million colors) display, you would need to upgrade to 8MB.
In most cases you can’t add memory to your video card—you would need to replace your current
video card with a new one with more memory.
3D video cards require more memory for a given resolution and color depth because the video mem-
ory must be used for three buffers: the front buffer, back buffer, and Z-buffer. The amount of video
memory required for a particular operation varies according to the settings used for the color depth
and Z-buffer. Triple buffering allocates more memory for 3D textures than double-buffering but can
slow down performance of some games. The buffering mode used by a given 3D video card usually
can be adjusted through its properties sheet.
Table 15.13 lists the memory requirements for 3D cards in selected modes. For memory sizes used by
other combinations of color depth and Z-buffer depth, see the eTesting Labs’ Memory Requirements
for 3D Applications Web site at the following address:
www.etestinglabs.com/benchmarks/3dwinbench/d5memfor3d.asp
Table 15.13 Video Display Adapter Memory Requirements for 3D Operations
Actual Onboard Video
Color Z-Buffer Buffer Memory Memory Size
Resolution Depth Depth Mode Used Required
640×480 16-bit 16-bit Double 1.76MB 2MB
Triple 2.34MB 4MB
24-bit 24-bit Double 2.64MB 4MB
Triple 3.52MB 4MB
32-bit 32-bit Double 3.52MB 4MB
Triple 4.69MB 8MB
800×600 16-bit 16-bit Double 2.75MB 4MB
Triple 3.66MB 4MB
24-bit 24-bit Double 4.12MB 8MB
Triple 5.49MB 8MB
32-bit 32-bit Double 5.49MB 8MB
Triple 7.32MB 8MB
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