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From: stevebr@primenet.com (Steve Brueggeman)
To: gibbs@narnia.plutotech.com (Justin T. Gibbs)
Cc: aic7xxx@FreeBSD.org
Subject: Re: does aha2940UW work with Seagate LVD disks?
Date: Mon, 08 Dec 1997 01:21:06 GMT
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References: <199712021749.PAA05341@hoggar.fisica.ufpr.br> <348622ea.343750@pop.primenet.com> <199712052148.OAA27749@narnia.plutotech.com>
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If the drives are in single ended mode, and they are asked to negotiate to
40Mhz, they will respond back with MSGIN for 20Mhz.

>
>> But, Single Ended mode does not support 40Mhz transfers (80MB/sec on a wide
>> interface).  Single Ended mode only supports Ultra-1 (20Mhz or 40MB/sec on
>> wide interfaces).  To get 40Mhz transfers, you need a host adapter that has
>> LVD drivers.
>
>Single Ended mode will support 40MHz transfers, but the cable length must
>be so short that you would only be able to put one or two devices on the
>bus.  I do not know if the devices will be so annoying as to not negotiate 
>40MHz if you ask for it and diffsense is false.  I certainly hope not, as
>there are certainly systems that are single target/single initiator where
>cable length is not a problem, but the number of signals wires is.