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Received: by minnie.vk1xwt.ampr.org with NNTP id AA5465 ; Fri, 01 Jan 93 01:46:11 EST Xref: sserve comp.unix.pc-clone.32bit:806 comp.unix.sysv386:26492 comp.unix.bsd:9306 comp.os.linux:20271 Path: sserve!manuel.anu.edu.au!munnari.oz.au!goanna!escargot!monu6!russ.cc.monash.edu.au!johnhm From: johnhm@russ.cc.monash.edu.au (John Morris) Newsgroups: comp.unix.pc-clone.32bit,comp.unix.sysv386,comp.unix.bsd,comp.os.linux Subject: Re: ET4000/W32 and VESA VL-Bus Message-ID: <1992Dec23.001916.18775@monu6.cc.monash.edu.au> Date: 23 Dec 92 00:19:16 GMT References: <1992Dec17.080653.4328@Informatik.TU-Muenchen.DE> Sender: news@monu6.cc.monash.edu.au (Usenet system) Organization: Monash University Lines: 41 X-Newsreader: TIN [version 1.1 PL6] Thomas Roell (roell@informatik.tu-muenchen.de) wrote: : >does anyone already using the new ET4000/W32 chip, perhaps in an : >VESA VL local bus version? How is the performance compared with : >ET4000AX and does it work with XFree86 1.1? : : I think nobody actually uses the ET4000/W32 currently, since I don't : know any SHIPPING hardware yet. I do assume that the ET4000/W32 is : much faster than the ET4000, based upon some expiriance I had with : other DRAM based accelerators. Take for example the WD90C31 (DS24X). : If you use the SVGA only driver you'll get around 9000 xstones, if you : use a driver that uses the internal acceleration capablities, you'll : get around 45000. It would assume that the latter number is the lower : limit for the ET4000/W32s performance. : : But there are some constraints you should think of: : : a) The performance of a DRAM based accellerator depends VERY much upon : the refresh frequency (i.e. dot-clock). Let's say you have a DRAM : bandwidth of 100MB/sec (let's assume it doesn't matter wether these : are RAS/CAS or RAS/multiple-CAS cycles). If you use a 1024x768 60Hz : resolution, you need about 65MB/sec for screen refresh only. This : leaves you with around 35MB/sec for doing graphics. If you use : 1024x768 72Hz, you need 75MB/sec for screen refresh. That means you : have only 25MB/sec for doing graphics. If you consider that you can : use the fast page mode accesses for screen refresh only and most of : the graphics operation won't be able to use them (since they are : interruped by screen refresh cycles), this computation is in fact : over optimisitic. : : - Thomas : : -- The ET4000AX does have support for VRAM (I have the chip manual), its just that most ET4000 boards use DRAM because its a bit cheaper. I assume the ET4000W32 also has VRAM support, so it will be up to board manufacturers to come out with VRAM designs. I also hope that the video memory can be accessed 32 (or 24) bits at a time for 24bit colour. John : -------------------------------------------------------------------------------