[comp.sys.sgi] VME interfaces also doc on writing drivers

olson@anchor.esd.sgi.com (Dave Olson) (08/31/90)

In <9008301913.AA12069@gdsnet.grumman.com> englund@GDSNET.GRUMMAN.COM (Dave Englund) writes:


| A co-worker of mine has a nifty video digitizer card he's trying to
| make work in a VME chassis containing an assortment of other strange
| cards. He is suspicious that something's wrong with this card, but
| can't tell for sure with his system.  I happened to discover that the
| Personal Iris I've been using has a double height VME slot just like
| he uses, and naively volunteered to help.  
|     Well, thirty Iris reference manuals later, I still haven't the
| foggiest clue as to how to address that bloody VME port.  I'm not even
| sure I should plug in the board, for fear that whatever base address I
| choose wil stomp some other device and really make a mess of things.
| Have any of you ever done ANYTHING like this before? 
| 

/usr/sysgen/system gives the VME address spaces allocated to assorted
devices (it differs from system to system, but that is explained in
the comments).

The manual "Writing Device Drivers for Silicon Graphics Computer Systems",
Document number 007-0911-010 gives a fair amount of info on VME and SCSI
driver writing, useful kernel functions (with pseudo-manpages), and some
tips on using the kernel debugger.  This is almost a necessity if you
want to write your own drivers.  One section covers memory mapped VME
devices, which often offers a fairly simple interface (if the card is
suitable).

The PI (4D20 and 4D25 series) makes no internal use of the VME bus, so
you don't need to worry about address conflicts, just pick an appropriate
one based on sysgen/system.
--

	Dave Olson

Life would be so much easier if we could just look at the source code.