Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!ucsd!sdcc6!mplvax!cdl
From: cdl@mplvax.EDU (Carl Lowenstein)
Newsgroups: comp.sys.dec.micro
Subject: Re: Micro VAX I
Keywords: micro-VAX I, hardware
Message-ID: <876@mplvax.EDU>
Date: 1 Jun 89 23:20:51 GMT
References: <18702@vax5.CIT.CORNELL.EDU>
Reply-To: cdl@mplvax.ucsd.edu.UUCP (Carl Lowenstein)
Distribution: usa
Organization: U.C. San Diego, Marine Physical Laboratory
Lines: 17

In article <18702@vax5.CIT.CORNELL.EDU> oyej@vax5.CIT.CORNELL.EDU writes:
>I am looking for information as to why the micro VAX I is unpopular.
>I believe that a major hardware design flaw is the reason that one doesn't
>hear about it anymore.

The MV1 does not have hardware for address mapping between DMA peripherals
and memory.  It would be a good trick to do so, since there is only one
Qbus for everything.

Storage which appears to a program as contiguous space (virtual addresses)
need not be at contiguous physical addresses in the Vax architecture.  This
greatly complicates transfer to and from mass storage devices such as disks
and tapes when there is no hardware help.  Probably that is the design flaw.
-- 
	carl lowenstein		marine physical lab	u.c. san diego
	{decvax|ucbvax}	!ucsd!mplvax!cdl
	cdl@mplvax.ucsd.edu