Jon Fullmer wrote:
> Yeah, and that's what I ended up doing.  I hate that answer, though.  The
> answer is, "Yes, this can be automated by software, but no one's done it, so
> do it manually." Alas, if only my programming skills were better, I would
> provide the solution, but they are not.
> 
> For those seeking the answer to this same question, I'm going to officially
> "for the record" declare that this element has not been programmed on NetBSD
> mac68k.  Any programmers feeling lucky?

Well, I think the SE/30 supports the page flipping bit in the VIA.
The OS could do a simple screen blank by putting all black pixels (all 
0xf's I think) into the other screen buffer. Then, when the blanking 
needs to happen the kernel just hits the page flip bit and displays the 
alternate page, and when the screen needs to be restores it hits the 
page flip bit again.

I believe the bit is DA1O_vPage2 defined in viareg.h.

Doing a little rooting around on the web, I managed to dig up an old mac 
tech article here:

http://www.mactech.com/articles/mactech/Vol.01/01.09/MemoryExamined/+macintosh+memory+map&hl=en&ie=UTF-8

It's from the Plus era, but I think the SE/30 still supports the page 
flip bit in the same way.

It seems the alternate buffer is kept at -0x8000 from the start of the 
main screen.

Anybody with an SE/30 want to give this one a shot?

-- 
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  Michael Zucca - mrz5149@acm.org
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  "I'm too old to use Emacs." -- Rod MacDonald
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