UNIX on uVAXen

[Art Berggreen]

>  I am looking for information on running UNIX system V on the Micro-VAX.
>  Particularly I would like to know:
>  
>  a) What are the major differences between the Micro-VAX and VAX-780 bus
>     architecture? Do I have to rewrite any drivers in order to put the AT&T
>     System V  VAX-780 release onto the Micro-VAX?
>  
>  b) Beside DEC's ULTRIX, are there any other UNIX systems that can be run
>     on the Micro-VAX?

You didn't specify which uVAX (I or II) but I'll assume a uVAX-II since I doubt
it would be worth the effort for a uVAX-I.

Any code in the UNIX kernel which is conditional upon cpu type will have to
be examined and support for the new processor type added.  This may not
require significant changes, just lots of work adding the new conditionals.

The overall bus architecture of the uVAX-II is similar to that of the UNIBUS
VAXen (especially the 730).  The CPU and cache have a private bus to the
memory and a bus adapter connects the QBUS to the memory bus.  The bus adapter
maps a portion of physical address space out to the QBUS.  In the uVAX-II
there are two areas.  One 4MByte section maps to the full QBUS for memory type
references.  Another 8KByte section is used for peripheral (BBS7) type
references.  The bus adapter also has a set of mapping registers to map pages
on the QBUS into pages of main memory.  UNIBUS machines have 496 map registers
needed to map the 18 address bit UNIBUS (I/O page is not mapped).  The uVAX-II
has 8K mapping registers to map the entire 22 address bit QBUS.  The QBUS
can be used as an 18 bit bus by only using the first 256KBytes of address
space (and only first 496 map registers).  This makes the uVAX-II look very
much like a UNIBUS VAX.  Interrupts are direct vectored like the 730 and 750.
As far as device drivers go, many of the newer DMA QBUS devices may not look
like any UNIBUS devices (because of 22 bit address registers), so new device
drivers may be needed.  Any interrupt driven device which has a UNIBUS
equivalent should be easier.  Documentation for the hardware may be a problem,
uVMS fiche listings would probably help.

Ultrix is the only UNIX I know of that runs on uVAXen.  I don't think BSD 4.3
will support uVAXen, and I doubt ATT will do it.  Uniq may be doing System V
support on uVAXen.
    				"Art Berggreen"<Art at ACC.ARPA>

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