From owner-freebsd-hackers Tue Jul 11 14:16:46 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id OAA04706 for hackers-outgoing; Tue, 11 Jul 1995 14:16:46 -0700 Received: from gndrsh.aac.dev.com (gndrsh.aac.dev.com [198.145.92.241]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id OAA04695 for ; Tue, 11 Jul 1995 14:16:43 -0700 Received: (from rgrimes@localhost) by gndrsh.aac.dev.com (8.6.11/8.6.9) id OAA16567; Tue, 11 Jul 1995 14:16:40 -0700 From: "Rodney W. Grimes" Message-Id: <199507112116.OAA16567@gndrsh.aac.dev.com> Subject: Re: Wanted: 100bT EISA ethernet recommendation To: dennis@et.htp.com (dennis) Date: Tue, 11 Jul 1995 14:16:40 -0700 (PDT) Cc: freebsd-hackers@freebsd.org In-Reply-To: <199507111840.OAA08675@mail.htp.com> from "dennis" at Jul 11, 95 02:40:34 pm X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Length: 1527 Sender: hackers-owner@freebsd.org Precedence: bulk > > >> > >> Tom's opinion.... > >> > > >> >On Tue, 11 Jul 1995, dennis wrote: > >> > > >> >> The question is, who would build one? EISA cards are too expensive to > build > >> >> and EISA is too slow for a 100mbs medium. If someone is making them then > >> >> I'll bet they have a much bigger marketing dept than engineering. > >> > > >> > That's wrong. EISA is fast enough for 100mbs ethernet. > >> > >> It can't be wrong, because any way you slice it its an opinion. Under light > >> load anything will work, but under heavy load its nice if your bus > >> throughput is greater than the bandwidth. If your EISA card is bus mastering > >> it can take over your machine under heavy load. For a workstation, sure, but > >> not for a server. And EISA is too expensive for a workstation. > >> > >> db > > > >EISA has a bus bandwidth of 33 mega*bytes* per second. > > > OK. I'll bite. Obviously my spec sheet is old/wrong or I don't get the new > math. The orginal EISA spec was 8.3mhz / 32 bits with 4-6 cycle access. This > is 88mbs best case with a real expectation of a little better than 60mbs > actual xfer capability. The knock on EISA has always been that its not that > much faster than ISA so this 32MB/s stuff must be new. You completely ignored bus master DMA which is 1 32 bit word per cycle or 33MB/sec. Your looking at PIO data rates, not DMA rates. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD