Path: utzoo!yunexus!hydroesm!jtsv16!torsqnt!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!snorkelwacker!bloom-beacon!EXPO.LCS.MIT.EDU!rws
From: rws@EXPO.LCS.MIT.EDU (Bob Scheifler)
Newsgroups: comp.windows.x
Subject: Re: Colormap Size of DirectColor Visual
Message-ID: <9005291239.AA11784@expire.lcs.mit.edu>
Date: 29 May 90 12:39:25 GMT
Article-I.D.: expire.9005291239.AA11784
References: <1990May29.020019.22162@eplrx7.uucp>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
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  Xdpyinfo reports that the DirectColor visual on a Sun has 8 colormap 
  entries.  Yet I can store 256 colors with XStoreColors.  Can someone 
  explain this "apparent" discrepency?

For DirectColor and TrueColor, you get the size of a "subfield", not the
total size of the map.  Read the protocol specification, end of Section 8:

The colormap-entries defines the number of available colormap entries in a 
newly created colormap.  For DirectColor and TrueColor, this will usually be
2 to the power of the maximum number of bits set to 1 in red-mask, green-mask,
and blue-mask.