Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!decwrl!world!ksr!jfw
From: jfw@ksr.com (John F. Woods)
Newsgroups: comp.sys.m68k
Subject: Re: Addressing VME147 in slave mode
Keywords: Need help programming VME chip
Message-ID: <3108@ksr.com>
Date: 11 Apr 91 21:26:26 GMT
References: <5840@mcrware.UUCP>
Sender: news@ksr.com
Lines: 20

davely@mcrware.UUCP (Dave Lyons) writes:
>	I'm trying to use two Motorola MVME147 boards in one cage
>and get them to be able to access each other's memory.  I've
>tried about every combination of values in the VME chip regs
>and all I get is bus error.  
>Here's what I think the register values should be
>Reg             Addr           Value in Sys Master         Value in Slave
>Slv Base Addr  $FFFE102B             $0A                        $05
>	I expected the System Master board to have its memory show up on
>the VME bus at $800000 (both boards have 4MB on board RAM) and I 
>expected the Slave to show up at $400000. 

I think your problem is right here.  According to page 4-28 of the VME147
manual, the low 5 bits are multiplied by the RAM size to determine the start
address, so with the values indicated, the System Master board's DRAM address
would start at 10 * $400000, or $2800000, and the Slave would show up at
$1400000.  I think you want this register to contain $x2 on the master and
$x1 on the slave to get the address mapping you state (for x, I would
recommend 2 to enable multiple-address RMC cycles to work correctly, hence
$22 and $21).