David Eckard wrote:

>In , on
>10/21/2004 
>   at 05:03 PM, htravis{at}attglobal.net said:
>
>>1. Can someone offer a correct calculation of how much memory is needed
>>for say 1280 x yyyy with True Color, and 8 virtual screens, and
>>capability to watch DVDs?
>>    
>>
>
>bytes = horiz * vert * 4
>
>1280 * 1024 * 32 bits (four bytes) = 5,242,880 bytes
>
>And if you want 8 virtual screen of mem, 41,943,040
>
>A 64 meg card, which today is considered basic, will do fine.
>
>NOTE: 24 bit color uses the same number of bytes as 32 bits of color.  you
>can break memory on one byte, two bytes, or four bytes.  You can't break
>it on three bytes.  So they use four for 24 bit modes.
>

Hi David,

I was always under the impression that whereas Windows for many years 
has used 32bpp, the reason that IBM (OS/2!) used 24bpp was that with any 
computer display there are still only Red, Green & Blue channels 
addressable as pixels - other memory can be used for Alpha-Channel 
blending - Transpacency.  There's no problem accessing memory at 3-byte 
intervals, especially with fast processors, as opposed to four, it's 
just slightly less efficient, as registers are in powers of two-wide 
these days, excepting some of the numeric coprocessor registers that are 
80-bits wide, but that's what the zero-extended moves to register 
instructions cater for, well in regular RAM/VRAM . Really just needs 
good tight coding! 4M is a happy medium for me to get reasonable 
resolution/coor depth, but 64M should cover most people quite 
adequately.  Probably Michal  Necasek is the person to give a definitive 
answer.

-- 
Regards,
Mike

Failed the exam for
--------------------
MCSE - Minesweeper Consultant and Solitaire Expert
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