Date: Sun, 27 Dec 1998 01:30:38 -0700 From: Brett Glass <brett@lariat.org> To: hardware@FreeBSD.ORG Subject: Information on Intel ISA 100BaseTX Adapter Message-ID: <4.1.19981227011014.05909300@mail.lariat.org>
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I've found some information on the Intel ISA 100BaseTX adapter, and to my admittedly untrained eye (I've written drivers before, but not for FreeBSD) it looks as if the ed driver can be adapted to handle it. The chip uses PIO (32-bit on EISA, 16-bit otherwise). While it's not DMA, it at least looks like a pretty good PIO implementation. It should be more efficient than chips with bad DMA that require memory-to-memory copies, especially if REP INSW and REP OUTSW are used for transfers. There's a document describing how to write drivers for the National Semiconductor DP83800 at http://www.national.com/an/AN/AN-995.pdf I'd appreciate it if those who have worked on LAN drivers could take a peek at the above URL and help me to assess the difficulty of adapting the ed driver. (Additional bells and whistles could include EISA and PnP support. I have absolutely NO idea how to do these on FreeBSD, but hopefully a lot of the code could be cribbed from other drivers.) Right now, the bottleneck in ISA systems with 10 Mbps Ethernet adapters is the Ethernet itself, since the ISA bus is lots faster than 10BaseT. Using a 100BaseTX Ethernet adapter would shift the bottleneck to the bus and CPU, which can run to their maximum ability and use the pacing in TCP to keep from getting swamped. (UDP could still swamp them, of course, but only if used in an ill-behaved way.) --Brett To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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