From owner-freebsd-hackers Tue Apr 4 17:36:46 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id RAA27576 for hackers-outgoing; Tue, 4 Apr 1995 17:36:46 -0700 Received: from tfs.com (mailhub.tfs.com [140.145.250.1]) by freefall.cdrom.com (8.6.10/8.6.6) with SMTP id RAA27570 for ; Tue, 4 Apr 1995 17:36:42 -0700 Received: by tfs.com (smail3.1.28.1) Message-Id: From: julian@tfs.com (Julian Elischer) Subject: Re: PCI/EISA/ISA performance To: terry@cs.weber.edu (Terry Lambert) Date: Tue, 4 Apr 1995 17:35:10 -0700 (PDT) Cc: matt@lkg.dec.com, vernick@cs.sunysb.edu, freebsd-hackers@FreeBSD.org In-Reply-To: <9504042255.AA20914@cs.weber.edu> from "Terry Lambert" at Apr 4, 95 04:55:48 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Content-Length: 988 Sender: hackers-owner@FreeBSD.org Precedence: bulk > Whose thumb are you looking at? 8-). > > VLB has a speed limit of 40MHz (typical cards die > 33MHz, though) > PCI has a speed limit of 33MHz > ISA has a speed limit of 12MHz > EISA has a speed limit of bus clock (mine runs at 50MHz) hmmmm (quick check of EISA SPEC) no, BUS speed on EISA != CPU clockspeed.. 1.3 Synchronous Data Transfer Protocol [bla bla]....Burst cycles with up to 33MB/s data transfer rate. table in section 1.4.2 [chop] 16bit............16.5MB/sec.........EISA cards only 32bit............33MB/sec...........EISA cards only 2.1.2 BCLK ... [bla bla]... frequency between 8.333 MHz and 6MHz.....[bla bla] PLUS many other references that state that the EISA bus is based around the BCLK signal.. > > > For instance, a DX4/75 PCI has the same bus transfer rate as a DX/50 EISA. hmm probably the PCI is faster, because most EISA transfers take a number of clock cycles... > > > Actually, MCA looks pretty good, compartively. 8-). always did.. julian