Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!stanford.edu!rutgers!njin!spcvxb.spc.edu!terry
From: terry@spcvxb.spc.edu (Terry Kennedy, Operations Mgr.)
Newsgroups: comp.sys.dec
Subject: Re: Can one put standard Q-Bus memory in the PMI bus of an 11/84?
Message-ID: <1991Apr28.204934.1292@spcvxb.spc.edu>
Date: 28 Apr 91 20:49:34 GMT
References: <72943@eerie.acsu.Buffalo.EDU> <1991Apr26.191350.47574@cc.usu.edu> <73510@eerie.acsu.Buffalo.EDU>
Organization: St. Peter's College, US
Lines: 20

In article <73510@eerie.acsu.Buffalo.EDU>, kalisiak@acsu.buffalo.edu (christophe m kalisiak) writes:
> The 11/84 has a Q-Bus CPU, which is the same as the 11/83. Therefore,
> one should be able to put Q-Bus memories in it, albiet with some reduction
> in speed.

  The dedicated memory slots in the 84 should be identical to the CD slots
in a BA23/BA123, but may very well be dedicated to PMI memory. While the
CPU certainly generates all the Q-bus signals, they may not all be wired to
the memory slots.

  Further (as I mentioned earlier) the bus converter card certainly doesn't
know what to do with non-PMI memory - when you try to DMA into non-PMI mem-
ory it will generate a PMI cycle which your boards will miss.

  I still think you ought to grab an old 84-only MSV11-J board. They can be
had for a few hundred dollars and it's an easier, supported, solution.

	Terry Kennedy		Operations Manager, Academic Computing
	terry@spcvxa.bitnet	St. Peter's College, US
	terry@spcvxa.spc.edu	(201) 915-9381