Re: Second Sight Question

[mjmahon@aol.com (Michael J. Mahon)]

Bryan Parkoff asked:

>    Low Res, High Res, Double High Res use main bank and aux bank and Super 
>Res uses $E0 bank and $E1 bank.  My question is which memory location Second 
>Sight's modes such as 640x400x256, 1024x768x256, and beyond are stored. 
>Someone told me that all pixel information are stored in Second Sight card's 
>RAM, but they do not store in the motherboard's RAM.
>    If pixel information is stored in Second Sight card's RAM, how can 65816 
>instructions access by modifying pixel data in the memory location that they 
>should be in motherboard's RAM.  Is there a special softswitch to transfer 
>pixel data from motherboard's RAM to Second Sight card's RAM?
>    I am not sure if the information is wrong.  Please let me know when you 
>find the information where pixel information is stored.  Thanks...

The Second Sight card has a processor on board that eavesdrops
graphics updates to Apple graphics pages and "translates" them
into "equivalent" updates in its own memory, which is the video
RAM on the Second Sight card.

This is much more like the video card model of the PC.

Of course, it would also be possible to provide modes on the
card in which the Apple processor could indirectly access the
video RAM on the card, but those modes would, of course, not
be compatible with Apple II graphics.

-michael

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