DEC Scrounging & SWTPC 6800 Update

From: Anthony Clifton <wirehead_at_retrocomputing.com>
Date: Thu Sep 4 16:21:52 1997

(BTW, I'm going to leave this thread public because I think it might
be of interest to collectors new to the PDP series and who might run
across machines like this.)

> > An 11/84 CPU alone apparently pulls 1100 watts
>
> A *fully-loaded* 10.5" 11/84 box will pull 1100 watts. A very much
> reduced configuration - just a CPU, memory, and (non KDA50) disk controller
> - will only draw 100 watts or so.
>
Well the backplane looked about half full roughly. So this is sounding
a bit more hopeful. I have $10 a month to spend on this machine for
electricity at about 8 cents per kilowatt hour so....

> I believe the spec for the RA-80 spinup surge current is 40 Amps. While
> running, it's probably about 7 amps.
>
I didn't have ALOT of time to look the machine over but I did look in the
back of the cabinet containing the TU80 and the RA80 and saw a sticker
that said "30 amps" which I ASSUMED referred to the RA80. I only ever
owned RL and RK series drives when I was collecting PDPs in the early
90s...what are the size etc specs on the RA80? A friend of mine and I
built an 11/34 system with 2 or 3 RK series drives and an older model
DEC 9 track drive. So I'm not completely ignorant but I'm still getting
used to the CURRENT state of the art in throwaway PDPs.
 
> A TU80 doesn't take much; about 50 watts with power off, and less than
> 200 watts with the blower and reels running.
>
Aha! This IS sounding alot more hopeful. Basically, if I could come up
with a controller to drive modern SCSI drives or something a bit less
power hungry, I could probably afford to run this guy at least all weekend
every weekend or something like that. Hmmm...I wonder if there's any
market for converting 9 track media to more modern forms? It'd only
take $60.00 a month, with modern drives, to run the beastie 24 hours...
perhaps less. =-)
 
> (presumably) is in the 11/84 will also talk to RA7n's and RA9n's. With
> a Emulex/CMD/Dilog ESDI or SCSI controller in the box, you can even hook
> up perfectly modern 3.5" hard drives.
>
Hmmmm...what's strange is that they claim they upgraded the drive around
two years ago. Upgrading TO an RA80 seems a bit strange in 1995. But the
front of the drive said RA80 so....

> > Now for my request, if anyone has schematics or technical drawings of this
>
> What do you specifically need? A print set for a complete configuration
> is several hundred 11x17" sheets...

Sheesh. I guess that's true...the print set for my old 34 was several
'books' of many pages a piece if I recall correctly. Ummm...if anyone
has the print set for an 11/84 they'd like to go to a good home then
let me know. =-) (If not, I'll probably run across one one of these
days.)

The machine DOES work apparently and the guy who operated it showed it to
me today. He claims that it worked fine when they shut it down 2 years
ago (yeah yeah I know) and it's just been sitting in the corner since
then. He claims that if I plugged it in, which I didn't have an
opportunity to do, it would come right up into RSX. We'll see after
next week. One other obstacle is that it all has the funky twisty safety
plugs on the AC cords but it's configured for 125 v etc so I'll replace
the plugs, like I did on my 34, with high quality normal ones.

Anthony Clifton - WireHead Prime
Received on Thu Sep 04 1997 - 16:21:52 BST