Path: utzoo!attcan!uunet!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga mentality
Message-ID: <10793@cbmvax.commodore.com>
Date: 11 Apr 90 16:21:40 GMT
References: <16296@snow-white.udel.EDU> <11059@bsu-cs.bsu.edu> <6647@wehi.dn.mu.oz> <3452@newton.physics.purdue.edu>
Reply-To: daveh@cbmvax (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 27

In article <3452@newton.physics.purdue.edu> sho@maxwell.physics.purdue.edu.UUCP (Sho Kuwamoto) writes:
>In article <6647@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes:
>>In article <11059@bsu-cs.bsu.edu>, mithomas@bsu-cs.bsu.edu (Michael Thomas Niehaus) writes:
>>> So the Amiga feels faster.  Can anyone answer the question of "why"?

>When windows are obscured on the Amiga, does the OS keep around a
>bitmap of the covered area, or is the program responsible for
>remembering what was there?  The mac uses the latter technique which
>saves on memory, but loses on speed.

That depends on the window.  There are three basic types.  The simplest type works much
like the Mac windows; the application gets a message when the OS thinks it should 
refresh the window.  The next one up lets the OS stash away pieces that get covered
and restore them when uncovered, so the application never needs to consider whether
it has been uncovered.  The third possibility allows the application to create it's
own bitmap.  The application then uses that bitmap for all it's drawing, and the OS
will copy the displayed portions of the bitmap to the window.  

>-Sho
>--
>sho@physics.purdue.edu  <<-- the *whole* screen?


-- 
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
                    Too much of everything is just enough