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Re: DECstation I/O adresses

To: linux-mips
Subject: Re: DECstation I/O adresses
From: hkoerfg1@ford.com
Date: Wed, 26 Feb 1997 09:49:23 +0000
Comments: Authenticated sender is <hkoerfg1@dttws020.merkenich.ford.com>
Priority: normal
Hi all,

[snip]
> 
> > A list of I/O adresses should not be that much of a problem, DMA            
> >   
> > transfers are another story. Anyway, if you are interested, i'll            
> >   
> > prepare a list from the NetBSD sources.                                     
> >   
> 
> The DECstations don't use DMA, IIRC ... the SCSI and Ethernet controller      
>   
> have their own little buffer RAM areas, the R3000 is responsible for all      
>   
> memory transfers ...                                                          
>   
> 

Michael, i'm afraid that is not fully correct. AFAIK all Turbochannel 
DECstations except the 5000/200 have an IO-ASIC on board which 
supports DMA-Channels for the SCSI, Ethernet and even the serial 
ports. These machines have no RAM buffers. But remember, this is 
second if not third hand information, so take it with a grain of 
salt. 

> regards,                                                                      
>   
>    Michael Engel  (engel@unix-ag.uni-siegen.de)                     

-- 
regards, Harald.

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