the memory must have a bandwidth of about 120Hz per bit. It just doesn't matter if it is text, dumb frame buffer, 2D, 3D, or, likely, some future technology.
So basically your long post comes down to "Carl's rule of thumb for display bandwidths."
Your rule only holds because basically 2d frame buffer displays really haven't changed much in the last 20 years. But 3d changes the whole picture.
In fact, your rule is already broken. Even 1 year old products (Voodoo3 and TNT2) were memory bandwidth limited. It's much worse today. You want proof? The Geforce2 has 3.33 times the textured fillrate of the Geforce (1600MT/480MT) but only scores 1.29 (45.2/35.1) times better at 1280x1024x32. (See www2.sharkyextreme.com
Why? Memory bandwidth limitations. The memory bandwidth needed is completely independent of the memory size. If they could ship 16MB video cards with 20GB/sec cost effectively they would in a heartbeat.
Want more proof? The Sony PS2 uses 4MB of eDRAM with a bandwidth of 48GB/sec. According to "Carl's Law", this 4MB should only require .48 GB/sec (4MB * 120Hz). Only off by a factor of 100! But then again, Sony might just have been stupid for having thought they needed this kind of bandwidth in the PS2.
Graphics technology has, over the years, desired a pretty much constant 120Hz (i.e. 60 to 180Hz) bandwidth per bit. I think that this is adequately explained by the bandwidth of the human eye. I don't think that it is going to change much
I disagree. It already has changed. It will change more. What about voxel renderers? Ray tracing hardware? Hardware NURBS acceleration? I have no idea what these possible (but maybe unlikely) technologies would require in memory bandwidths. But the odds that they follow 120 Hz/bit is small.
You need to update your rule of thumb.
Plaz
P.S. You quoted the word "moderness" as if I used it. Even late at night, I try to avoid words like that.
My appologies for not being clear. I was using italics for your quotes throughout the message. I quoted "moderness" because it's not really a word. Your quote was directly above that:
Thus with more modern technology, the memory bandwidth problem doesn't get better |
