PDP 11/44 working

From: Don Maslin <donm_at_cts.com>
Date: Sun Oct 6 23:33:01 2002

On Sun, 6 Oct 2002, John Lawson wrote:

>
> Yesterday (and into the night), I powered up one of the two 11/44
> machines rescued from San Diego. Did the usual thing of taking out the
> cards, documenting cables, cleaning, dusting, and then turning things up
> slow and watching voltages - no worries, the systaem came up and was
> subsequently reassembled in it's as-acquired config.
>
> It boots from two Micropolis 51/4" half-height drives sitting in the
> card bay of a card-less 11/23 chassis... which has been re-badged by
> Centaur Software. The front panel switches control write-protect, now.
> I don't have models right now, since I didn't work on that device yet.
> But they connect to a Dilog DU686 controller card - a quad-height card
> with one common 34-pin ribbon and individual 20-pin ribbons going to each
> (of 2 drives). This is... MFM, no? the original owner called them SCSI
> but somehow I think not.... Anybody have Doc on this Dilog card?

Certainly not SCSI, but are either ST506/411 (what you called MFM) or
ESDI. Check the controller capabilities or the interface of the drives
before you swap in a different drive that "looks the same". The
connectioons are NOT the same.
                                                - don

> The machine currently runs RSX-11M V4.2 G Build 58, or so it says. File
> creations run from 1980 to 1997, when the machine was shut down. The
> physical devices are mostly from '79 to '83.
>
> It has Fortran, Basic, and Oregon Pascal V2 installed.
>
> There is an RL02 system, working nicely, and couple of multi-line EIA
> muxes, one DEC (M7819) DZ11 and a Ditronics 16-line EIA mux.
>
> There is also a Digital Pathways SLC-1 real-time clock/calendar that
> sits in the Console line and responds to certain interrogatories from the
> System... fairly funky, IMHO.
>
> It came with printsets for all major subsystems, and the Blue Wall, and
> about 20 RL02 packs, most of which are blank.
>
>
> If everything goes as planned, I will bring this machine to VCF5.0 and
> let it be Played With.
>
>
> And, looking back into the Files, it was Bill Bradford who first brought
> this machine to the attention of Chris Kennedy, who referred it to me, and
> voila! here it is warming my (pleasantly) chilly garage while we wait to
> see if Autumn is going to actually stay for a while. It was pushing 90
> here this afternoon... wierd! Should be fixing to snow....
>
>
> So - now to wake up the Second System. Since this was a
> mission-critical machine, there are actually two complete
> identically-configured 11/44a and disk subsystems. The RL02 is shared by
> changing cables to the machine in use, and the TTY lines are all hooked up
> to a bank of DPDT mini switches (also by Centaurus Software) so that, if
> one system crashes, the other can be cut over by changing one connector
> and flipping the switches.
>
>
> Anyway - not a particularly 'rare' or 'significant' system, but
> certainly fun to mess around with. It certainly gets stares from my
> nieghbors. One of the local kids looked in while it was running this
> evening and asked "what's *that* thing?". I told him it was a computer.
>
> "No Way!!"
>
>
> Cheers
>
> John
>
>
Received on Sun Oct 06 2002 - 23:33:01 BST