On Sun, October 5, 2014 3:02 am, John R Pierce wrote:
> On 10/5/2014 12:48 AM, ken wrote:
>>
>> I sincerely *hope* that it isn't some kind of trend that video cards
>> are using shared memory instead of dedicated memory on the card
>> itself. All machines I've bought or built since the late '90s have
>> had video cards with a .5G of dedicated memory. This is mostly
>> because video memory is physically different, using static RAM rather
>> than dynamic RAM. The former is something like ten times faster than
>> the latter.
>
> NO video card uses static ram, at least not since the early 1980s.
>
> the modern CPUs with integrated graphcis controllers such as the Intel
> HD4500 stuff is excellent,
John, I would respectfully disagree. The bad thing about "shared" memory
video cards is fundamental in the architecture. They use as video RAM a
portion of main RAM, that means they place the video traffic (30, or 60,
50 25 frames per second multiplied by number of pixels worth) onto memory
bus. This traffic has nothing to do with anything but the screen and just
doesn't belong there. It is logically independent on anything and should
be kept separate from memory bus - physically.
I mentioned single board computer I soldered for my kid back then based on
Z80 processor as an example of how rudimentary is to mix video traffic
into memory bus. It was OK to do that on trivial amateurish single board
computer. It is awful to step that low from architecturally good dedicated
video ram away on modern sophisticated computer. My computer science
degree rejects that and asks to take from "inventors" of that away their
computer science degrees.
Sorry about harsh attitude. Crap deserves crap.
Valeri
> at least on MS Windows systems. the main
> memory controller on these CPUs has HUGE bandwidth, the video display
> overhead is lost in the noise unless maybe you're running dual huge
> screens. a dedicated controller might be 2-3X faster or more at 3D
> gaming graphics, but its not usefully faster at normal desktop
> graphics. dedicated controllers use significantly more battery power
> than integrated ones, a consideration on a portable laptop.
>
++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
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