Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!wang!comm.wang.com!lws From: lws@comm.wang.com (Lyle Seaman) Newsgroups: comp.unix.sysv386 Subject: Re: Ethernet Cards Message-ID: <1990Dec13.152306.5471@comm.wang.com> Date: 13 Dec 90 15:23:06 GMT References: <707@denwa.uucp> <200@bigfoot.first.gmd.de> Organization: Wang Labs, Platform Comms. Lines: 34 tmh@bigfoot.FOKUS.GMD.DBP.DE (Thomas Hoberg) writes: >In article <707@denwa.uucp>, jimmy@denwa.info.com (Jim Gottlieb) writes: >|> 6386E WGS). We switched to the 3Com 3C503 and all was fine. Our video >|> card (Olivetti supplied) doesn't have the option to switch it into >|> 8-bit mode. I wonder if the 16-bit Ethercard Plus would have worked. You don't need to have an option to switch a 16-bit board into 8-bit mode, just put it in an 8-bit slot. >I really wonder whether there is any advantage to using a 16-bit Ethernet card >then, other than having a couple more IRQ lines available. The WD Ethercards >use only a 16k window and I guess nobody could afford to waste 128k of address >space for that. In any case the bandwidth provided by an 8-bit slot should be >quite sufficient for a 10Mb Ethernet. I can't understand why you can't give up 128k of address space, unless your machine is maxed out on RAM. Most machines have limits at 16M, and 128K isn't a whole lot, compared to that. I don't know what the bandwidth of the PC bus is, but it's not as simple as you think. To keep an Ethernet card pushing data out at 10Mb/s, you can either 1. keep the bus running at 10Mb/s constantly, or 2. blast data across the bus occasionally, buffer it on the card, and dribble it out at 10Mb/s. Doing (1) is pretty difficult (impossible), so you have to resort to (2). That's what a 16-bit card with extra RAM does for you. Furthermore, it's doubtful that the older cards would be able to get data out at 10Mb/s even under condition (1). -- Lyle Wang lws@comm.wang.com 508 967 2322 Lowell, MA, USA uunet!comm.wang.com!lws The scum always rises to the top.