Date: Tue, 4 Apr 1995 17:35:10 -0700 (PDT) From: julian@tfs.com (Julian Elischer) To: terry@cs.weber.edu (Terry Lambert) Cc: matt@lkg.dec.com, vernick@cs.sunysb.edu, freebsd-hackers@FreeBSD.org Subject: Re: PCI/EISA/ISA performance Message-ID: <m0rwJ3u-0003vzC@TFS.COM> In-Reply-To: <9504042255.AA20914@cs.weber.edu> from "Terry Lambert" at Apr 4, 95 04:55:48 pm
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> 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
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