Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cbmvax!jesup
From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.arch
Subject: Re: Let's pretend
Keywords: Intel, 586, windows
Message-ID: <18001@cbmvax.commodore.com>
Date: 24 Jan 91 04:08:49 GMT
References: <3042@crdos1.crd.ge.COM> <450@lysator.liu.se> <5800@labtam.labtam.oz>
Reply-To: jesup@cbmvax.commodore.com (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 31

In article <5800@labtam.labtam.oz> graeme@labtam.labtam.oz (Graeme Gill) writes:
>In article <450@lysator.liu.se>, zap@lysator.liu.se (Zap Andersson) writes:
>>  NEVER understood why this is not common practice in todays computers! I mean
>> what CAN be easier than to include in the gfx chip that 'when beam reaches
>> this'n'that row/column, start displaying bitmap-data from this'n'that memory!
>> The Amiga is the closes I've seen, supporting these 'semi-hardware' (the
>> amiga uses a co-processor) as horizontal slices of display. With a faster
>> co-processor (i.e. faster than 1 pixel bitclock) you could have hardware
>> windows support! You will NEVER need to worry about memorys overlapping, or
>> in what memory to write! You just write to your 'virtual' screen, and the
>> display chip takes care about it ALL.

>about a generation behind mainstream processors. Doing windowing in software
>allows a great deal of flexibility in fixing bugs, keeping up with standards
>developments, ease of porting code to new generations of hardware, etc., 

	Another reason: most current ways of doing windowing in hardware
have a fixed number of windows they can support (especially if they
each have a different color palette on a non-direct-RGB system).  The Amiga
has screens ("hardware horizontal windows"), and on each screen you can have
windows.  Note that there are blank lines between screens: it needs to update
the bitmap pointers, color table, etc.  The screens are draggable, though they
remain a solid horizontal slice (actually, you can sort of do HW windowing,
but it's rather limited since you can't change much on the fly across a line).

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.commodore.com  BIX: rjesup  
The compiler runs
Like a swift-flowing river
I wait in silence.  (From "The Zen of Programming")  ;-)