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From: cs326ag@ux1.cso.uiuc.edu (Loren J. Rittle)
Newsgroups: comp.sys.amiga.misc
Subject: Re: AT&T using patent to go after people using X
Message-ID: <1991Feb24.135201.9052@ux1.cso.uiuc.edu>
Date: 24 Feb 91 13:52:01 GMT
References: <1748@pdxgate.UUCP>
Organization: University of Illinois at Urbana
Lines: 32

In article <1748@pdxgate.UUCP> bartonr@eecs.cs.pdx.edu (RTFM) writes:
>In article <1991Feb22.090412.28321@ux1.cso.uiuc.edu> cs326ag@ux1.cso.uiuc.edu (Loren J. Rittle) writes:
>>Seems like this `back store' patent would also cover some aspects of intuition.
>
>  Would someone care to explain what this "back store" is?
>
>================================================================================

Sure, I'd love to...
And I can explain it in plain terms too!
Mac and many others (let's not single them out, I'm just sure you 
have at least seen one of these... :-) ---
When a window comes to the front, the application gets requests
to rebuild the parts of the window that were exposed...
...the Mac does not have `back store' or as some would say,
`backing store'

Amiga and others (X 11R[34] comes to mind) ---
When a window comes to the front (or any piece is exposed),
the low level graphics subsystem can replace the bits in the
window that are now visible (became exposed) because it kept
a `back' (where the term `backing store' comes from, I would guess)
up of the hidden parts of the window.  And if any drawing commands
would have accessed those hidden areas they *were* updated (in the
back store area).

Loren J. Rittle
-- 
``NewTek stated that the Toaster *would not* be made to directly support the
  Mac, at this point Sculley stormed out of the booth...'' -A scene at the
  recent MacExpo.  Gee, you wouldn't think that an Apple Exec would be so
  worried about one little Amiga Device... Loren J. Rittle  l-rittle@uiuc.edu