Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!iuvax!purdue!ames!sgi!ted@bangles.sgi.com
From: ted@bangles.sgi.com (Ted Wilcox)
Newsgroups: comp.sys.sgi
Subject: Re: RAM
Message-ID: <37879@sgi.SGI.COM>
Date: 13 Jul 89 16:53:53 GMT
References: <8907111747.aa25894@SMOKE.BRL.MIL> <37817@sgi.SGI.COM>
Sender: daemon@sgi.SGI.COM
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 18

In article <37817@sgi.SGI.COM>, jmb@patton.sgi.com (Jim Barton) writes:
>
> In article <8907111747.aa25894@SMOKE.BRL.MIL>, frobinso@cirm.northrop.com (Fletcher Robinson) writes:
> > Does anyone know if CPU main memory(RAM) in a 4D70GT is dual-ported ?
> > i.e. is it accessible from the VMEBUS ?
> 
> The answer is yes and no.  Only the lower 8 megabytes of CPU memory are
> addressable from the VMEBus.  For a description, see the 'system' file
> in /usr/sysgen.

Also, you need to note that the memory will answer ONLY to NON-PRIVILEGED
data access requests (address modifiers 0x39 0x9).  If you try to assert
supervisory address modifiers, the memory will not answer.
--

Ted.
ted@sgi.com
{sun|decwrl|pyramid|ucbvax}!sgi!ted