Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!uunet!mcrware!davely
From: davely@mcrware.UUCP (Dave Lyons)
Newsgroups: comp.sys.m68k
Subject: Re: Addressing VME147 in slave mode
Keywords: Need help programming VME chip
Message-ID: <5986@mcrware.UUCP>
Date: 15 Apr 91 15:27:49 GMT
References: <5840@mcrware.UUCP> <3108@ksr.com>
Reply-To: davely@mcrware.UUCP (Dave Lyons)
Organization: Microware Systems Corp., Des Moines, Iowa
Lines: 36

In article <3108@ksr.com> jfw@ksr.com (John F. Woods) writes:
+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).

Yeah, that's what I found out.  I think the VME147 manual I have must be 
fairly old.  It showed two groups of two bits, the lower two bits setting
the slave address in the standard address space and the upper two bits 
setting the slave address in the extended space. From this I had thought 
that $0A for the master board would give me 2 * $400000 = $800000 for the 
standard space and the same thing for the extended space.  

Thanks to all who replied, davel

-- 
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