Subject: Re: Vaxstation 3100???
To: Gunnar Helliesen <>
From: Matt Thomas <>
List: port-vax
Date: 11/27/1996 15:45:24
> But seriously, is anyone working on support for the onboard DSSI and
> ethernet for the 3300/3400? If not, why not simply ask Digital for their
> Ultrix source code? They don't market Ultrix any more and it is after
> all "BSD-ish" so it should provide at least a starting point for a
> NetBSD port...? Or would that be cheating? ;-)

Sorry, ULTRIX is still being sold and is supported.  Digital is unlikely
to release source for it or parts of it.  

DSSI/MSCP/SDI/etc. are a mess since they get heavily involved with Digital's
intellectual property rights (which I say no desire to discuss).  I've asked
the powers-that-be about whether DSSI information can be disclosed.  We'll

There are basically two DSSI chips used, the SII (also known as the EDA640
and is the same chip used for SCSI in the DECstation 3100 (PMAX) and the
DECsystem 5100 and VAXstation 35x0 (Firefox) and DSSI in the DECsystem 5500;
note the DSSI connector is electronically incomaptbile with SCSI so it's
impossible to use the SCSI capabilities of the SII in DSSI configurations) 
and the SHAC (Single Host Adapter Chip; used in newer systems such as the
uVAX 4000 systems with DSSI).

However, DSSI is really a mini-CI.  The DSSI controller is like a CI 
controller and each drive (ISE) is similar to an HSC with a single disk.
So if you are going to write a driver for a DSSI chip, you will also need
to write the correspond CIPPD, SYSAP and SCS layer components before you
can even begin to talk MSCP.  However, after you finish you will most of
the way to supporting real CI adapter and HSCs. :-)

The KFQSA oesn't have the above problems since it present a UQ-port SSP
interface to the O/S and does all of the work needed to talk to the drives

That being said, the goal of commonality raises its head here.  Much of
the MSCP (etc.) support is really platform independent.  MSCP devices exist
on DEC MIPS platforms and DEC Alpha platforms.  The KFESA (EISA) and KFPSA
(PCI) DSSI controllers provide for the possiblity of i386, PowerPC, and
other ports as well (not likely but ...).

Even most of the Q-bus driver should be written with portability in mind
since the DECsystems 5400/5500 have Q-buses.

Matt Thomas               Internet:
3am Software Foundry      WWW URL:
Westford, MA              Disclaimer: I disavow all knowledge of this message