NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/sys/apple2/24281

Internet Message Format | 1992-11-20 | 1.7 KB

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From: [e-mail] (Matthew W. Hacker)
Newsgroups: comp.sys.apple2
Subject: Animation and video card design...
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Date: 20 Nov 92 23:43:50 GMT
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   A sugestion came up a while back that a video card should
have separate memory from the GS, and that if something wanted
to access video memory directly, it could DMA to the card.
As I pondered this idea, I had a couple of questions/comments:

1) All the GS/OS stuff should use the toolbox, so if the card
   was coprocessed, this wouldn't be bad. Right?

2) If it shadowed the GS's video memory, then it would be backwards
   compatible with older stuff that did direct memory writeing.

3) Sounds pretty good except for one thing.  What about animation?
   Doesn't animated stuff still use direct access?  Then having
   to write to memory, and then DMA to the card is really going to
   slow things down.

Of course the only other real option (as I see it, anyhow) is to
design a memory card that let the memory be accessed from two
sides.  This would make animation twice as fast, but with the
8 meg limit on the GS might be a bit of a trade-off.  Along
with having to put two cards in your machine.

How many people out there have a full eight megs in their GS?

Comments / suggestions?
--
Matthew W. Hacker                           [e-mail]
                                            AppleII forever!