flat assembler
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> DOS > How to directly access SVGA |
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neville 24 Apr 2011, 10:51
Yes I agree bank switching is very slow.
Not sure about direct register/port access, but if the video card supports linear frame buffering (LFB) that is the way to go. The LFB is mapped to the top of 32-bit memory space, and the video mode starts with 4 e.g. 4103h is mode 103 in LFB mode. _________________ FAMOS - the first memory operating system |
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24 Apr 2011, 10:51 |
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me239 25 Apr 2011, 00:15
neville wrote: Yes I agree bank switching is very slow. |
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25 Apr 2011, 00:15 |
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revolution 25 Apr 2011, 01:56
me239 wrote: Yes, but how do operating systems like Windows handle such fast graphics all in high resolution SVGA? |
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25 Apr 2011, 01:56 |
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me239 25 Apr 2011, 02:18
revolution wrote:
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25 Apr 2011, 02:18 |
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revolution 25 Apr 2011, 02:32
The BIOS does not "speak to the driver". The BIOS accesses the video card directly. A driver also accesses the video card directly. If you have a driver for your card then you don't need to use the BIOS.
If you have the specs for your card then you can access the card directly also. But the hard part is getting the full specs. |
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25 Apr 2011, 02:32 |
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JohnFound 25 Apr 2011, 07:56
Every video card have some ROM that contains so called Video BIOS. The problem is that usually this video BIOS supports only very small amount of the cards features. The modern video cards supports it only for compatibility purposes. The full speed/features of the video card can be use only by some code, working directly with the hardware - i.e. driver.
However, the specifications for this hardware is often hard or impossible to be obtained. The manufacturers often release drivers only for Windows and recently for Linux. Actually the tragedy of all new OSes is the lack of video drivers. This was a problem for Linux for many years. (now is more or less fixed). |
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25 Apr 2011, 07:56 |
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vid 25 Apr 2011, 09:21
Quote: Every video card have some ROM that contains so called Video BIOS. The problem is that usually this video BIOS supports only very small amount of the cards features. The modern video cards supports it only for compatibility purposes. Specifically for graphics during booting, and for Windows without proper driver installed (in such case it is quite common to use bank-switched mode). |
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25 Apr 2011, 09:21 |
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