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Thread: PDP-11/73 new to me!

  1. #1

    Default PDP-11/73 new to me!

    As my first dive into DEC hardware, I have always been wanting a PDP-11 of any sort to learn, repair, and generally tinker with. It is from before my time (used before I was born), but that is part of the charm to me to learn systems like this. I was a former Navy Fire Controlman where my mainframe was based on a Unisys 2200 hardware setup, which I mastered and maintained for years before leaving. So this is my first foray into "commercial" hardware of the era.

    I dug up (literally from a scrap pile) a PDP-11/73 and VT420 that is all in fantastic shape. After giving it a quick look to ensure no PCBs or capacitors are destroyed, I booted it into RSX-11 (cannot tell what version) and it auto-loaded the control software that it used on a daily basis. I then learned this was the station monitoring and alerting system for our old NEC analog video microwave system we have across the state (still installed but defunct for the past 15 years). It used to have the PDP-11 in our master control room with a direct link to our microwave supervisory circuit, with dial-up modems connected to it so engineers can be alerted remotely and view the status. From what I learned, the system was designed to send out pages to technician pagers to tell them "something is wrong, log in and look".

    Now that the system is verified running, I am going to 1) strip it down to give it a more thorough cleaning and inspection, 2) see what spare parts I can find for the system and get parts to keep it alive as needed, and 3) install a new OS which I want to eventually link this to HECnet and have some fun with it.

    Number 3 is my biggest concern at the moment because other than the 8 DB25 connectors on the back (assumedly for the dial-up modems and a few printers), there is no way to link this to Ethernet without me buying said cards and adapters. I currently have a DECserver 200/DL but that is pretty useless for my intended use and might sell it to someone who wants such a piece. I have plenty of Cisco switches I can adapt to DECnet and thus eventually get onto HECnet but no idea what I will need to get this system to the level of function it deserves as a relic that still keeps ticking.


    Any help would be appreciated! I am currently scrounging PDF manuals for my own records, firmware for the CPU board, and the like... but heck even DCL is new to me and I need to learn an entirely new ecosystem!

  2. #2
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    Default

    Don't worry, when the time comes, there are plenty of qbus Ethernet adapters still around so that you can put your machine on the internet. Just search DELQA on your favorite auction site.

    All the manuals you need are on bitsavers.

    Is there any more DEC hardware in this scrap pile? You had better snag it!

    Lou

  3. #3

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    Quote Originally Posted by Lou - N2MIY View Post
    Don't worry, when the time comes, there are plenty of qbus Ethernet adapters still around so that you can put your machine on the internet. Just search DELQA on your favorite auction site.

    All the manuals you need are on bitsavers.

    Is there any more DEC hardware in this scrap pile? You had better snag it!

    Lou
    Still digging. Found 3 more terminal keyboards but no terminals as of yet. Also found 3 SCSI DAT drives and a host of cables but still looking for more hardware. Somewhere in the pile there SHOULD be a few Alpha servers.

    Also dug up some Sun hardware which I know there’s more hiding.

    Sadly we are known for decommissioning hardware, warehousing it, and forgetting it exists until the warehouse needs to be cleared out. Since it’s my department scrapping the equipment I get to sift through it and save what I want now. Sadly I feel like most of the good hardware (including a Data General Eclipse) is already gone.

  4. #4
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    I think many DEC folks don't do "Forums" , "Facebook" or other things that they see as "social media", they yearn for DECNOTES,so whilst support on here is good you may find the more techy folks elsewhere. Why don't you join the HECNET list if HECNET is your goal.

    http://www.update.uu.se/~bqt/hecnet.html

    assuming you are in the USA (if you fill in your profile it will show us) some one may even give you the necessary card. There is also a DECTEC list which is generally very quiet, but will burst into life when a technical question arises..

    http://dectec.info/
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  5. #5

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    Congratulations, and thank you for saving it from the junkpile! I'd love to get my hands on a nice PDP-11/73 in the BA23 pedestal case one of these days. Hmm, maybe a microVAX in a BA23, too.

  6. #6

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    Quote Originally Posted by g4ugm View Post
    I think many DEC folks don't do "Forums" , "Facebook" or other things that they see as "social media", they yearn for DECNOTES,so whilst support on here is good you may find the more techy folks elsewhere. Why don't you join the HECNET list if HECNET is your goal.

    http://www.update.uu.se/~bqt/hecnet.html

    assuming you are in the USA (if you fill in your profile it will show us) some one may even give you the necessary card. There is also a DECTEC list which is generally very quiet, but will burst into life when a technical question arises..

    http://dectec.info/
    Thanks for the links! I will be signing up for both since I want to get into this hardware. My uncle was an engineer for Wang Computer who ended up at DEC, Compaq, HP... so his background was from the PDP-8 to Itanium days working specifically on their storage solutions. He was excited to see this hardware still alive - mostly because he never thought of saving the hardware himself as DEC and Compaq would toss them in recycling dumpsters when updating their labs.

    Quote Originally Posted by NF6X View Post
    Congratulations, and thank you for saving it from the junkpile! I'd love to get my hands on a nice PDP-11/73 in the BA23 pedestal case one of these days. Hmm, maybe a microVAX in a BA23, too.
    A microVAX II is on my list as well! I don't have a ton of space in this house so I wanted the "smaller" models to eventually perhaps rack mount with other computer hardware I want to purchase/maintain... but I have also thought about updating this PDP to utilize SCSI disks, add more RAM, and tinker with it a bit and then sell it and make room for some Alpha equipment.

    As for the specs of this actual unit... it COULD be better... since this was just used for monitoring and paging I guess it didn't need top shelf specs but I'd still want to upgrade some components:

    Slot 1: M8190 KDJ11-B CPU
    Slot 2: M8067 512K RAM
    Slot 3: M8067 512K RAM
    Slot 4: M3104 DHV11 8-line Asynch MUX
    Slot 5: M8639 RDRX Disk Controller

    RX50 Floppy
    RD52A Disk with RSX-11 installed and set to auto-load proprietary monitoring software for our now defunct microwave network (replaced with a DS3 microwave circuit... equipment exists but hasn't been turned on in 15 years)


    My thought was to 1) upgrade RAM cards to at least 1Meg cards each - preferably 2Mb if they weren't so rare and going for $500 a pop, 2) upgrade RDRX and RD52A to a SCSI controller and drive at minimum - maybe the SD emulated piece I've replied to in another post, 3) add ethernet, and 4) replace floppy with the TK50 tape unit or a DLT/DAT unit if one was made for it. That way I can set it up with Ultrix or another OS and put it online with nightly backups and better reliability than the RD52A. Coming from the military side I know how unreliable and quirky these MFM drives can be... and I don't have their funds to acquire or refurb this drive when it fails...

  7. #7
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    Quote Originally Posted by NF6X View Post
    Congratulations, and thank you for saving it from the junkpile! I'd love to get my hands on a nice PDP-11/73 in the BA23 pedestal case one of these days. Hmm, maybe a microVAX in a BA23, too.
    We've got a MicroVAX II in a BA23 at Computer Corps that needs to be tested... I just haven't powered it up yet.

  8. #8
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    You'll find a serious population of DECheads on the CCtalk mailing list.

    Sort of retro, as it's not an online web forum, but an email list, but there's plenty of interest there.

  9. #9

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    Quote Originally Posted by NF6X View Post
    Congratulations, and thank you for saving it from the junkpile! I'd love to get my hands on a nice PDP-11/73 in the BA23 pedestal case one of these days. Hmm, maybe a microVAX in a BA23, too.
    I've got a PRO 380 in a BA23 ...
    I use my C128 because I am an ornery, stubborn, retro grouch. -- Bob Masse
    Machine room: http://www.floodgap.com/etc/machines.html

  10. #10
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    Quote Originally Posted by ClassicHasClass View Post
    I've got a PRO 380 in a BA23 ...
    Are you sure it is a BA23? Or just a similar sized box? A standard BA23 box holds an H9278-A 8-slot Q-bus backplane. As far as I know the PRO systems are not based on standard Q-Bus modules.

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