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From: howard@cpocd2.UUCP (Howard A. Landman)
Newsgroups: comp.sys.mac,comp.windows.x
Subject: Re: Mac II color graphics
Message-ID: <474@cpocd2.UUCP>
Date: Thu, 5-Mar-87 16:50:27 EST
Article-I.D.: cpocd2.474
Posted: Thu Mar  5 16:50:27 1987
Date-Received: Sun, 8-Mar-87 05:59:49 EST
References: <10231@teknowledge-vaxc.ARPA> <1338@husc6.UUCP>
Reply-To: howard@cpocd2.UUCP (Howard A. Landman)
Organization: Intel Corp. ASIC Services Organization, Chandler AZ
Lines: 32
Xref: mnetor comp.sys.mac:1638 comp.windows.x:208

In article <1338@husc6.UUCP> hadeishi@husc7.UUCP (Mitsuharu Hadeishi) writes:
>	As far as I know (haven't seen the spec sheets from Apple yet)
>the software of the color workstation will support up to a full 16-bits
>per R, G, B.  The software queries the display device by sending it
>a 16-bit RGB value (16-bits per R, G, and B) and getting back the
>"closest" value the display device can handle.

This sounds like X windows.  Perhaps Apple is migrating toward X compatibility.
Good idea if so.  For more info peruse comp.windows.x, or get an X manual.

>That is,
>the "color monitor" has extra logic to communicate with the host
>machine and tell it the closest 16-bit RGB value it can produce
>for a requested value.

No, no, no (I hope)!  This can all be done in software if necessary, and most
present implementations of X do it that way.  On the other hand, full X allows
you to open a window on *someone* *else's* *machine* if you have permission,
and in that case ("color monitor" == other machine) you are close to right.

>So software written today should be able to handle the full 16-bits of RGB,
>but the actual card can only support 8-bits (for a total of
>2^(8*3) or about 4 million colors).  The card can display 8 bit planes,
>for 256 colors per display.

8 * 3 = 24.  2^24 =~ 16M (not 4M).  So you can choose any 256 colors out of
a palette of 16 million.  This is typical of many graphics controllers
(e.g. AED 512, Metheus Omega series, etc.).
-- 

	Howard A. Landman
	...!intelca!mipos3!cpocd2!howard