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From: scc@cl.cam.ac.uk (Stephen Crawley)
Newsgroups: comp.arch
Subject: Re: built-in security features
Message-ID: <652@scaup.cl.cam.ac.uk>
Date: 27 Jan 89 00:43:32 GMT
References: <8846@nsc.nsc.com> <3300046@m.cs.uiuc.edu>
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Organization: U of Cambridge Comp Lab, UK
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Don Gillies (gillies@m.cs.uiuc.edu) message about Xerox workstations
contains some factual errors.

The working microcode for a Xerox D machine (Dandelion, DandyTiger, Dolphin,
Dove = Daybreak, etc) is loaded from Hard disc, Floppy disc or from the
Ethernet when the machine is booted.  Different microcode is used for 
Mesa, InterLISP, Smalltalk and (I think) for standalone diagnostics.  
When a new release of a product comes out, you often get a new microcode
image.  Eg the XDE 5.0 release had microcode with extra instructions
to implement C character pointer operations.

The source code of many products IS available.  In the Mesa world, the
source code for the base operating system (Pilot), for XDE and for
all of the XDE tools are available.  True, Xerox won't release the 
source code for their network servers or for Viewpoint.  

The assembly languages are no longer proprietry.  I don't think that 
the InterLISP and Smalltalk instruction sets ever were.

> I doubt if *ANYONE* outside Xerox has ever broken the product 
> factoring system.

I think you'd be surprised how easy it is :-)

-- Steve