Tony..first I have only 2megs and I need 16bpp or a better depth.:)
second, I can above 1024x768 but..hmm..I need 75hz or more..
So 1024x768x16bpp = 1572864 so there's a min 2megs card.
Also the bandwidth is dependent on the number of vertical and horizontal
pixels and then the vertical refresh rate. This approximation grossly
implies the calculation: given that the vertical pixel addressability is
Y, horizontal pixel addressability is X and the refresh rate is R.
To account for the additional time required for the vertical blanking
interval, Y is multiplied by 1.05. The additional time required for the
horizontal blaking is about 30% of the scan time, so use 1.3x. Note that
30% is very conservative with most new monitors. In order to do am exact
calculation, you would have to know the vertical and horizontal blanking
intervals for the mode in question, as well as the horizontal scan
frequency. So the resulting approximation is:
bandwidth = 1.05Y*1.3X*R..so the the approx. bandwidth req. for..let's
say 1280x1024x75 is 1.05*1024*1.3*1280*75 (for 75hz, which is the lowest
ergonomical freq.).
1.05*1024*1.3*1280*75 = 134 mhz..
Clearly these are gross simplification, so use this equation for
approximations only.
134 mhz..it's ok!..and with ATI's dot-clock:
(--) Mach64: PCI: Mach64 RageII+DVD rev 154, Aperture @ 0xe0000000,
Registers @
0xe1000000, Block I/O @ 0x6500
(--) Mach64: Card type: PCI
(--) Mach64: Memory type: SGRAM (5)
(--) Mach64: Clock type: Internal
(--) Mach64: Maximum allowed dot-clock: 200.000 MHz
(**) Mach64: Mode "1024x768": mode clock = 98.900
(**) Mach64: Mode "800x600": mode clock = 69.650
(**) Mach64: Mode "640x480": mode clock = 45.800
(--) Mach64: Virtual resolution: 1024x768
(--) Mach64: Video RAM: 2048k
is gettin' even better. But with 107s (which seems to me is the entry
line) I have only 70khz horizontal refresh and I _know_ this leads to 110
mhz bandwidth. Don't get me wrong, quality is very good, but hmm..those
specs reminds me of my old Sampo520. No difference. So, I don't use
1280x1024 because I don't have enough ram on my video card, on the other
hand..damn 107s doesn't go up to 75hz for 1280 or above. Need a 107 or a
19" one (when my GeForce256ddr comes..:).
michael.
