Path: utzoo!attcan!uunet!samsung!interlan.InterLan.COM!interlan.interlan.com!dave From: dave@interlan.Interlan.COM (Dave Goldblatt) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: EISA vs. ISA Message-ID: Date: 14 Dec 90 14:20:26 GMT References: <51097@eerie.acsu.Buffalo.EDU> Sender: news@interlan.Interlan.COM (No News is BAD News) Reply-To: dave@interlan.interlan.com Distribution: na Organization: Racal InterLan, Inc., Boxborough, MA (1-800-LAN-TALK) Lines: 63 In-Reply-To: raster@pawl.rpi.edu's message of 14 Dec 90 03:37:07 GMT Nntp-Posting-Host: slam.interlan.com In article raster@pawl.rpi.edu (Jerry D Bain) writes: Actually, EISA slots have *two* layers of connectors. The first layer of contacts are ISA compatible. This makes the EISA bus ISA compatible. FULLY If a card wants to support the EISA extensions (32 bits, bus mastering), it has an extra set of gaps in the card-edge connector (like the single gap in a regular 16bit card) that allows it to reach all the way down into the second set of EISA control lines. Correct. The second row of fingers is located between the gaps of the upper row; this second set of fingers are approximately two-thirds the size of the normal ISA fingers. > MCA inferior to EISA? This is not what I've heard. I thought > that MCA allows for peripheral cards to talk to each other without CPU > intervention. I'm not sure that EISA can do this. Can it? The EISA standard can run at a much higher transfer rate than the MCA standard can. It supports all the functionality of the MCA bus without being tied the the IBM-proprietary patents. If memory serves, MCA runs at only 20mbit/s while EISA runs at 32mbit/s. Partially correct. I think EISA can run 33MB/s, but IBM recently announced new "features" in MCA that can push it up to 64MB/s; I seem to recall they were going to do this with some funky design, but I don't remember the details. EISA *does* support bus-mastering. There are many boards on the market already that fully support the EISA bus. Correct. Although "many" is probably an overstatement; there aren't all that many out there yet. As someone mentioned, we have a 32-bit EISA adapter. It's fast. Really fast. In fact, one board can load 100% of the network. (Warning to parents: Don't let your children do this on a corporate LAN.) :-) It also supports Type-C DMA. There are a number of other network adapters announced, but I haven't seen any myself. By the way, you can do bus mastering on (most) ATs, too. IBM claimed otherwise, but we (and others) proved them wrong.. ;-) My personal preference? (if anyone cares ;-) EISA. MCA's improved performance was the excuse IBM used to try to regain its control over the PC market. EISA was the industry's response. I haven't seen an ISA board yet which doesn't work in an EISA machine (which conformed to the EISA spec, of course). That to me is the biggest reason to invest in an EISA box -- you don't have to immediately run out and dump all of your existing hardware -- at some point you'll probably want to, but it's at your leisure. Note: The opinions reflected herein are solely mine, and were brought to you by a lack of sleep. -dg- -- "You can twist perceptions * Dave Goldblatt [dave@interlan.com] Reality won't budge..." * Diagnostic Engineering - Rush * Racal InterLan * Boxborough MA (508) 263-9929