feipoa wrote:I'm looking at your graph and am noticing that the Tseng ET400AX ISA receives the same score as a Trident 8900CL. Why is that?
Well first there are different Revisions of the ET4000AX with different performance. Also the Trident 8900Cx (as well as the 8900D) belong to the faster Trident cards.
You should also consider the tested modes. Cards vary a lot if you look at regular 320x200, ModeX or SuperVGA Modes either banked or Linear Frame Buffer (for local bus cards).
The main point here is the difference between planar modes and non-planar modes (also called unchained / chained). Now if you have the regular 320x200 a DWORD write to graphics memory with STOSD writes 4 bytes. While these are consecutive in main memory they are each 4 bytes apart in graphics memory. So you transfer from
01 02 03 04 to 01 xx xx xx 02 xx xx xx 03 xx xx xx 04 xx xx xx. Considering just performance, it happens that on the ISA bus it is split to 16 bit transfers for a 16 bit card, so e.g. 01 02 is written and the graphics card needs now two memory writes, even if it has 32 bit memory bus width.
In planar mode a 32 bit wide write would be split into two 16 bit transfers over the ISA bus and could be combined by the graphics card to a single 32 bit write to graphics memory.
You see it really depends on the mode and on the buffering the graphics chip does. The performance really depends on the mode you look at. There won't be a single best card that handles every situation at top speed. You have a per mode ranking.