From:	CSBVAX::MRGATE!RELAY-INFO-VAX@CRVAX.SRI.COM@SMTP 17-OCT-1988 09:36
To:	ARISIA::EVERHART
Subj:	Re: PFN mapping on a uVax II (VMS)


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Date:    Sun, 16 Oct 88 10:42:52 PDT
From:     nagy%warner.hepnet@LBL.Gov (Frank J. Nagy, VAX Wizard & Guru)
Message-Id: <881016104252.20400503@LBL.Gov>
Subject: Re: PFN mapping on a uVax II (VMS)
To:       Info-VAX@kl.sri.com
X-ST-Vmsmail-To: INFO_VAX

> Can anybody please tell me what the magic number is to do PFN mapping to
> the I/O space on a uVax II (or KA650)? I wrote a little program to loop
> through memory reading words from the following mapped locations:
>    IOUV2$AL_QB0SP + (0x00E000 through 0x00FFFE)
>...
> with no response from any device. Substituting IO780$AL_UB0SP for the
> IOUV2$AL_QB0SP and running the program on a 780 displays, as expected,
> all the Unibus locations that are present (ala SYSGEN's SHO /UNIBUS).
     
MicroVAX-II (also true for the -3xxx systems) physical addresses are
as follows:

	0x20000000 - 0x20001FFF		QBus I/O registers
					IOUV2$AL_QB0SP = 0x20000000

	0x30000000 - 0x303FFFFF		QBus memory
					IOUV2$AL_QB0MEM = 0x30000000

If you want to read QBus memory, then use IOUV2$AL_QB0MEM as the base
address since on the QBus memory and the I/O registers are in separate
address spaces selected by a single QBus control line.  The MicroVAX
allows for the direct control of this line ("2" vs "3" in high nibble)
and also allows for use of the full 4 MB of QBus memory space.


= Frank J. Nagy   "VAX Guru & Wizard"
= Fermilab Research Division EED/Controls
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