Re: DECstation R4000 CPU upgrade

From: Maciej W. Rozycki (macro_at_ds2.pg.gda.pl)
Date: 06/28/04 

Date: Mon, 28 Jun 2004 13:56:46 +0200

On Sun, 27 Jun 2004, Dennis Grevenstein wrote:

> I couldn't find a replacement power supply for my 5000/150
> so quickly and as I don't have a lot of free time at the moment
> I put the R4000 CPU in a Personal DECstation. It fits in
> there and it works if you reset one of the switches on the
> CPU module, but I wonder if there was only one CPU module
> for both the /150 and the /50. In the /150 the CPU cooler
> sits right in front of a fan, but in the /50 only half
> of the cooler is actually in the flow of air.

 There was only one. The switch you refer to selects between motherboard
types, indeed. The other switch selects MB ASIC decoding for the ROM slot
at 0x1fc00000 (the one used for bootstrap -- the other one is at
0x1f800000), to go either to the daughtercard ROM (normally holding KN04
firmware) or to the motherboard ROM (normally holding KN02-BA/CA
firmware).

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