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Thread: DECmate II

  1. #1
    Join Date
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    Portland, Oregon, USA
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    Default DECmate II

    Hey guys, someone here in town is selling a DECmate II. I'm curious about it and wonder if it's something I should even bother thinking about picking up?

    Pictures:
    https://imgur.com/a/kc9eQmq

    The guy says the computer works but the monitor isn't working -- which could easily be the machine OR the monitor that has an issue. (The monitor has cataracts as well which will only get worse until the front cover is removed.) Just looking for thoughts on something like this and if it would be a neat system to get. Also, any thoughts on what something like this (in this condition) might would be worth?

    Thanks!
    -- Adrian

  2. #2

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    It all depends on what he wants for it.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  3. #3
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    The guy is asking $160 but I assumed I would negotiate him way down. I don't think there is much market for it and looking at the pics it seems to just be taking up space in his garage.
    -- Adrian

  4. #4
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    I am envious - I have been after one of these for a while!!!

    It is basically a PDP-8 (the CMOS microprocessor kind).

    I would make sure the main unit is actually working and it is just the monitor that has failed.

    If you don't end up buying it - I may be interested in trying to organise a deal (subject to the dreaded shipping issue from the States to the UK that is).

    Dave

  5. #5
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    Quote Originally Posted by daver2 View Post
    I am envious - I have been after one of these for a while!!!

    It is basically a PDP-8 (the CMOS microprocessor kind).

    I would make sure the main unit is actually working and it is just the monitor that has failed.

    If you don't end up buying it - I may be interested in trying to organise a deal (subject to the dreaded shipping issue from the States to the UK that is).
    The guy has no idea if it works. He never used it before -- so really no way to know if it's actually working. I can't even find a manual for it online. Dave, do you know what kind of video output this has? I found one PDF from DEC that says it uses RS107 standard monochrome output. Oh wait -- I found something -- Recommended Standard 170 is also known as NTSC. Interesting. Reading up on it, it sounds like a fascinating old machine which is why I am interested in it.

    So Dave, I would think shipping something as heavy as a DECmate II tower to the UK would cost hundreds of pounds!
    -- Adrian

  6. #6

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    The simple way to know if it's actually working would be to plug it in, pop in a disk, switch it on, and listen to see if the disk drive starts loading anything.
    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

  7. #7
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    >>> So Dave, I would think shipping something as heavy as a DECmate II tower to the UK would cost hundreds of pounds!

    I would think so too!

    Dave

  8. #8
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    Quote Originally Posted by commodorejohn View Post
    The simple way to know if it's actually working would be to plug it in, pop in a disk, switch it on, and listen to see if the disk drive starts loading anything.
    I'm not sure this machine comes with any floppies. From my reading the system uses quad density single sided disks. I suppose it trying to access any 5.25" disk is a good sign. Do you think these use a normal Shugart style disk interface so I could use a Gotek or does Digital do everything proprietary?
    -- Adrian

  9. #9
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    The RX50 pinouts can be found here http://www.bitsavers.org/pdf/dec/dis...chem_Jul82.pdf about half way down. The SA400 equivalent is here http://www.classiccmp.org/dunfield/r/sa400.pdf on page 12.

    There are some subtle differences. Check out pin 2, pin 6, pin 32 and pin 34 for example.

    Dave

  10. #10
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    Interesting -- it only appears pin 2 and 34 differ from normal PC drives. The SA-400 was missing the side pin 32 and drive select 3 on pin 6 but that was used later on most PC drives. The PIN 2 and 34 are interesting. It appears 34 was a disk change line like the Amiga -- not sure on the pin 2 as the schematics don't seem to have that anywhere but on the pinout page.

    Thanks for this though.... Well we'll see. We'll see if the seller is willing to deal.
    -- Adrian

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