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Re: Problem with PMAD-AA / DECStation 5000/200

To: "Armin F. Gnosa" <mipslist@gnosa.com>
Subject: Re: Problem with PMAD-AA / DECStation 5000/200
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Mon, 13 Aug 2001 13:30:30 +0200 (MET DST)
Cc: linux-mips@oss.sgi.com
In-reply-to: <002601c121a0$de4f2fa0$237900d9@shodan>
Organization: Technical University of Gdansk
Reply-to: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Sender: owner-linux-mips@oss.sgi.com
On Fri, 10 Aug 2001, Armin F. Gnosa wrote:

> That sounds like an interesting alternative to pulling the PROM out of
> its socket. Then, a program running on a DECStation 5000/200 should be
> reading from 0x1F81C0000..0x1F1FFFFF, right? One question about Byte
> Merging: Does it mean that I don't have to read bytewise but instead
> DWORD-wise?

 The system ROM is mapped from 0x1f800000 up to 0x1f83fffff (and repeated
at 0x1fc00000) and is 256kB in size on my /240.

 Although I cannot verify it, docs state that the /200 contains the
following ROMs:

- the system ROM from 0x1fc00000 up to 0x1fc7ffff (repeated at
0x1ff80000), 256kB in size,

- the PMAD-A ROM from 0x1f9c0000 up to 0x1f9fffff, 32kB in size,

- the PMAZ-A ROM from 0x1f4c0000 up to 0x1f4fffff, 32kB in size. 

 The system ROMs are presented on the whole data bus, while the option
ROMs are only presented on 8 least significant bits.  The merging can be
switched off for I/O ASIC systems (I haven't tested the exact behaviour of
this configuration) but it seems to be hardwired for the /200.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +


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