Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!samsung!uakari.primate.wisc.edu!caen!ox.com!math.fu-berlin.de!fauern!NewsServ!!roell From: roell@informatik.tu-muenchen.de (Thomas Roell) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: Mentor & Trident VGA cards - which one is the best ? Message-ID: <1991Apr15.141215.10486@Informatik.TU-Muenchen.DE> Date: 15 Apr 91 14:12:15 GMT References: <1991Apr3.071713.6290@fel.tno.nl> <3725@d75.UUCP> <1991Apr11.095521.26017@Informatik.TU-Muenchen.DE> <1991Apr12.110818.7937@odin.corp.sgi.com> Sender: news@Informatik.TU-Muenchen.DE Organization: Inst. fuer Informatik, Technische Univ. Muenchen, Germany Lines: 50 In-Reply-To: erik@westworld.esd.sgi.com's message of 12 Apr 91 11: 08:18 GMT > 74 VGA read/write > >Of course, the number you *really* want to reduce is that VGA read/write >number. Using VRAM or clever VGA design (like the high(er)-speed cache on >the video-7 fastwrite) should be able lower that number substantially. >Of course, the cleverly designed VGAs aren't going to sell for US$130 >any time soon. Ok thats right. But I think you cannot reduce is much. Say you use a 33MHz 386, reads take as long as writes, (74/2) and you use 32bit access (same as the numbers were computed for). Now you have the fact that a VGA (the newer ones) are accessed 16bit wise. This means one access takes about 18 Cycles. That is equal to 545ns. The normal system ram has about 200ns. How should that be improved ??? a) 32 bit bus => expensive EISA machine b) Using VRAM => very expensive VGA Thus it's just wise to buy a 8514a which is much faster through the use of VRAM and a special graphics processor who eleminates the remaining cpu cycles. BTW, the VideoSeven VRAM is only half fast as a ET4000 cause the latter one uses 16bit accesses and then V7VRAM only 8bit ones. >The 8514 is nice, but if you really need speed, forget about the PC:-). >I'm from the workstation world, and most PC-based servers I've seen >are slow compared to even the typical workstation. The machine on >my desk can do solid fills at something like 140 million pixels per >second. Sorry that I strongly disagree. I'm also using a SPARC2. This one is in the overall performance SLOWER than my 386 box. The mips numbers you read are rediculus !!! But the SPARC is a RISC and the 386 is CISC. Anyway the compilers run faster on the 386, so I much more like the 386. Also the graphics are faster (through the use of a 8514a). And all for less than half of the price. And don't forget one fact: If you have a workstation, you have to share it with other users. Most 386 boxes are used by just one person !! 140 million pixels !!!! Wow. But since pixelfilling is not all one uses normally in GUIs lets talk about the overall performance. Whats the xstones ? Ok, we all dislike benchmarks, but they tell us aproximately how fast a Xserver is. Doing this fast filling is easy. Just use VRAMs and a graphics processor that uses a floodfill alorithm utilizing the shift-registers of a VRAM. - 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..."