marc@gem.stack.urc.tue.nl (Marc Saes) (05/30/91)
Hi there to all users of Thomas Roell's X11 port and an ET4000 based VGA board. I have seen several different ET4000 boards lately and I noticed extremely large performance differences. For example the difference between the TRICOM card and a VGA ULTRA card: (both running 1152x900 resolution at 62 MHz vs. 65 MHz dot clock, the SCLK's of the ET4000 were 36 MHz and 50 MHz respectively):(a 386 25MHz system without cache was used): x11perf -scroll100 73/sec with TRICOM, 152/sec with VGA ULTRA. This means scrolling performance practically doubled, which is very important since scrolling performance is the more noticable bottleneck of VGA boards. I would like to compile a comparison list between different ET4000 cards under X11, I will post the results. The questions I need answered are: * What is the name of your card * Does it have a frequency synthesizer (2 crystals) or multiple crystals (4 and more) * What is the SCLK of the ET4000 (if you don't know, leave this out) * Name all the crystal frequencies * Mention your bus speed (8 MHz, 12.5 , .. 16 MHz) * Mention the number of wait states (if you know them) * Do the following benchmark from a fresh system with one xterm: x11perf -seg100 -scroll100 report the output * Mention your screen resolution * Which CPU, cache or no cache, CPU clock freq Thanks for your cooperation, Marc.
roell@informatik.tu-muenchen.de (Thomas Roell) (05/31/91)
>62 MHz vs. 65 MHz dot clock, the SCLK's of the ET4000 were 36 MHz and 50 MHz >respectively):(a 386 25MHz system without cache was used): I think the SCLK is the important thing. The SCLK is the base for all DRAM IO. The faster the SCLK the faster is the DRAM access (if you baord has slower DRAMs, the manufactorer would have used a slower, while inexpensiver quartz). Thus a SCLK with 50MHz provides much more speed. But the imense improvement of speed results from another fact, too: If you SCLK is driver at 36MHz, all almost available memory bandwidth is spent up for display refresh. If you have a SCLK of 50MHz about half the bandwidth is free for CPU accesses. Thus the 386 can driver the Et4000 at full io-speed. - Thomas -- _______________________________________________________________________________ E-Mail (domain): roell@lan.informatik.tu-muenchen.de UUCP (if above fails): roell@tumult.{uucp | informatik.tu-muenchen.de} famous last words: "diskspace - the final frontier..."