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Thread: What did I do to my PDP-8 today.

  1. #1

    Default What did I do to my PDP-8 today.

    I am starting a thread which I hope others will post to detailing what they did to their PDP-8(s). I steal this idea shamelessly from forums in some of my other hobbies. Feel free to talk about anything you have been working on as long as it is PDP-8 related. Software, hardware, restoration, maintenance, I am interested in all of it and what others are doing. And if I am interested in what you are doing, I am almost certain others are as well.

    With that in mind I hope to see decent traffic here and I will follow up with my first post.

    Doug
    Doug Ingraham
    2nd owner of Straight 8 SN1173
    5 other PDP-8's including an 8/i and a DECSet 8000
    SOL-20

  2. #2

    Default

    Today finds me working on my recently acquired DECmate II. (Yes, it is a PDP-8.) Really!

    I have been collecting all the pieces to make a working machine and currently I am whitening the VR201 case by having it sit out in the sun. It has been exposed for several days so far and is quite a bit improved over the yellowish greenish color it had when I received it.

    Also on the VR201 I am soaking the face of the monitor in plain water in order to dissolve the PVA holding the protective glass to the face of the vacuum tube. This isn't the worst case of cataracts I have seen but it is the first time I have had to deal with it. I am going to give it a week or two and if it doesn't just fall off I will go to plan B. I don't know what plan B is yet.

    I dug out an old DOS machine, keyboard, monitor and hooked it up. Installed a 3.5 inch floppy as drive A: and a 5.25 inch 1.2 mb floppy as drive B:. Next problem was locating a version of DOS. I have hundreds of lbs of floppies but it is no longer in any kind of order. I eventually ran into a Win 95 boot disk which I remembered is sort of the last version of DOS. Plugged it in and it booted! YAY! You might be asking yourself why I needed a DOS machine and the answer is to run PUTR so I can burn some RX50 images to allow me to boot the DECmate. The next problem was how to get the data onto the 3.5 inch media. This turned out to be easier than I expected because while looking for a copy of DOS to boot I ran into a USB 3.5 inch drive (two of them actually) which I had never used. Got them from a friend years ago. Plugged it into my win 10 laptop and was able to look at the WIN 95 boot disk. Formatted a couple of 3.5 inch floppies and copied the PUTR files over to them and the image I needed. From this point it went like a champ. I will have to wait until I get a VR201 working to know if the DECmate can read it but PUTR seems to have no problems.

    I think that is enough for today. I hope you found this of interest. Looking forward to hearing what you are doing!

    Doug
    Doug Ingraham
    2nd owner of Straight 8 SN1173
    5 other PDP-8's including an 8/i and a DECSet 8000
    SOL-20

  3. #3

    Default

    Ah, I really need to get back to my -8 Roguelike project...there was no way I was gonna have it ready for VCF West, but since that plan was cancelled due to the apocalypse anyway, I guess I've got another year to get it done
    Computers: Amiga 1200, DEC VAXStation 4000/60, DEC MicroPDP-11/73
    Synthesizers: Roland JX-10/SH-09/MT-32/D-50, Yamaha DX7-II/V50/TX7/TG33/FB-01, Korg MS-20 Mini/ARP Odyssey/DW-8000/X5DR, Ensoniq SQ-80, E-mu Proteus/2, Moog Satellite, Oberheim SEM
    "'Legacy code' often differs from its suggested alternative by actually working and scaling." - Bjarne Stroustrup

  4. #4

    Default

    I too have a Decmate-II. Hard disk doens't work so it doesn't do much. The floppy drive in it seems to also have problems as it may click a few times but does not read. I'd like
    to be able to create images for it too, but have no old DOS PC anymore. I may have to swap a floppy drive from another DEC machine I have to see if that helps. I have never
    used a Decmate before. I prefer the blinken lights variety of 8, but sold my 8i and 8e long ago when I moved from Pa to NM. Best of luck to you.

  5. #5

    Default

    I got this particular DECmate II from Vince Slyngstad. We were able to verify that it would boot from floppy using one of the WPS (Word Processing System?) diskettes. We weren't able to make a copy of this boot disk at the time and didn't know why but I think I understand why now. We did several things wrong, wrong media and we had write protected the destination floppy. I took it all apart a couple of weeks ago and cleaned out all the grime. I 3D printed new feet for it as the original rubber feet were almost completely gone and I couldn't find anything even close to the right shape, size or materials. At the moment I have a monitor which is soaking in water, an untested keyboard, and an untested spare RX50 drive. The keyboard is in what I would class as very good condition cosmetically so I am hoping it will work. The drive popped up on an EBay search and was a reasonable price and I was lucky enough to win it uncontested. I have a lot of appropriate media and I would be happy to make some images for you once I know they work. From my research I discovered that you need to use a 1.2 mb drive to write the image but you do not use the quad density media. The RX50 makes use of only one side but uses the 96 tracks per inch ability of the high density drive. It writes that single side at lower bit rates. A really oddball format. It is a little surprising that a DOS PC even with special software can handle it.

    Doug
    Doug Ingraham
    2nd owner of Straight 8 SN1173
    5 other PDP-8's including an 8/i and a DECSet 8000
    SOL-20

  6. #6
    Join Date
    Dec 2013
    Location
    Near Milwaukee Wisconsin
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    1,263

    Default

    Hi Doug, good to here from you. I find that the weather is still too warm for computer work. Most of my time has been spent on old cars. Have been working on a 1913 Model T roadster that came from Newton Iowa. Lots of fun. BUT......I have been collecting old FORTRAN IV books. I want to re learn FORTRAN. It was the first language I used back in the late 60's. I have the DEC version of FORTRAN IV and have worked out a few easy programs. In fact last winter, I found a bad transistor on my EAE boards. The FORTRAN square root function, which uses the EAE was giving wrong answers. I also cheat a little Simh goes a lot faster than the PDP8e and the teletype. Hope it's not too hot in South Dakota. Mike.

  7. #7
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    4,026

    Default

    Hey Mike, long time no hear.

    I thought it was ‘T’ weather for you !

    It has been hot this side of the Pond recently as well. By the time we get AC installed the weather will change though!

    Dave

  8. #8
    Join Date
    Dec 2013
    Location
    Near Milwaukee Wisconsin
    Posts
    1,263

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    Hi Dave. Yup, it's been hot here also. And the humidity has been high. The old one two punch is getting harder to take on this old body. Here is a picture of the little beauty. I'm at the wheel. Mike
    SMALL1212.jpg

  9. #9
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    4,026

    Default

    Nice.

    But someone has put the steering wheel on the wrong side ...

    Dave

  10. #10
    Join Date
    Dec 2013
    Location
    Near Milwaukee Wisconsin
    Posts
    1,263

    Default

    It's called, polarity. It depends on with side of the pond you are on. Sort of the right hand rule or something like that. Mike

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