From: Tim Shoppa <shoppa@alph02.triumf.ca>
Message-Id: <9804151403.AA13468@alph02.triumf.ca>
Subject: Re: PDP-11 Newbie Alert --- (gotta start somewhere)
To: pups@minnie.cs.adfa.oz.au
Date: Wed, 15 Apr 1998 07:03:00 -0800 (PDT)
In-Reply-To: <9804151317.AA04337@toes.its.uwlax.edu> from "Milo Velimirovic" at Apr 15, 98 08:17:47 am
Content-Type: text
Sender: owner-pups@minnie.cs.adfa.oz.au
Precedence: bulk

> Has anyone looked at the possibility of retrofitting older pdp11's with modern
> switching power supplies to ease the electricity demands...?  
> (donning asbestos suit in anticipation of cries of "heretic" and "Frankenstein"...)

It's hardly heretical - all Unibus 11's have always had switching
power supplies for the high-current (+5V and - for core machines - +20V)
lines.  Depending on the exact model, +15 and/or -15 may have come
from a linear power supply, but these are very low-current lines and
not a major factor in power consumption.

The way to greatly reduce the power consumption of a big Unibus -11
is to go to a more modern CPU and memory in the original backplane.
For an extreme example, a 11/70 with 2 MW of core memory in MJ11 boxes
will draw about 70 Amps at 120 VAC, for over 8kW of power consumption.
But you can replace the 11/70 CPU set with a Quickware replacment
and take the CPU part of power consumption down to 3 or so Amps at
120 VAC, or under 0.4kW.

> >As to operating system versions, 2.11BSD needs at least an 11/73 or 83 to run,
> 
> How about an 11/44? 

Yep, does work.  (I had always been promising Steven that I would get
the FP emulator working so I could run it on my FP-less 11/44, but
I got a FP board before I got the emulator going.  So you need the FP
board for a 11/44, still!)

Tim.