PowerBook 500 Series: External Video Support

What is the highest bit depth the PowerBook 520 & 520c and PowerBook 540 & 540c are capable of using with an external monitor attached?

Can the internal video RAM be expanded to provide for more colors?
The highest bit depth at 640X480 (or any resolution) is 8 bits per pixel.

The PowerBook 500 series come with 512K VRAM, which is not expandable.

External Video Support
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Display                    Resolution(HxV)       Bits/Pixel

12-in. RGB Display            512x384            1-8bpp
12-in. Monochrome Display     640x480            1-8bpp
13/14-in. RGB Display         640x480            1-8bpp

VGA (60 Hz)                   640x480            1-8bpp
SuperVGA (56 Hz)              800x600            1-8bpp
VESA 1024x768 (60 Hz)        1024x768            1-4bpp

Portrait Display              640x870            1-4bpp
Portrait Display              640x818            1-8bpp

16-in. RGB Display            832x624            1-8bpp

Multiple Scan 17 Display      640x480            1-8bpp
                             832x624            1-8bpp


Multiple Scan 20 Display      640x480            1-8bpp
                             832x624            1-8bpp
Published Date: Feb 19, 2012