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Thread: unpopulated 3rd party MXV-11-ish card worth it?

  1. #1

    Default unpopulated 3rd party MXV-11-ish card worth it?

    Hi!

    I'm still struggling a bit with getting a bootstrap card for my 11/23, and the usual prices they go for on Ebay are above what I can/want to spend on it. Basically, any eprom card that can be assigned to the right addresses can be used. Then I found this:

    http://www.ebay.com/itm/Qbus-DEC-Vax...kAAOSwX61ZBIZ0

    It looks like a 3rd party MXV-11-bf type of multifunction card - it's definately a serial card, and then it has those rom sockets..

    It's not fully populated, but it looks to me as if the bus interface logic and ROM sockets are there - could be it had been used as a boot card previously.

    Would it be worth it getting this card and try to get it to act as bootstrapper?

    What are your thoughts?


    Current systems: PDP11/23, ZX-spectrum, MEK-6802D5, Ampex 210 CRT terminal, ZX-spectrum
    Current projects: 8085 Altair 8800 compatible
    Looking for: DEC RX-50 drive, QBUS ROM card, intel 8288

  2. #2
    Join Date
    Jan 2010
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    Central VA
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    Default

    Huh, I see wiredforservice still takes all of their equipment pictures with a potato

    At this point it's probably worth it for the bus drivers, assuming they work. Decent price, especially considering the seller.

  3. #3

    Default

    If you don't mind paying shipping from Australia (perhaps $30-$40) and don't mind some non-DEC weirdness, I'm happy to donate an un-tested General Robotics TBC board, as pictured here -> http://avitech.com.au/?attachment_id=1901. I may be able to find documentation for it (but can't promise this). ISTR these have one serial port, boot ROM capability, and the ability to generate the LTC signal for the processor (if you wire up the secondary side of a small AC transformer to the 0.156" spacing pins on the front edge of the board).

    I have a project that might provide an alternative solution for you. It involves sitting an Arduino between the PDP-11's console serial port, and the console terminal. You press one button on the Arduino and the Arduino then presents a boot menu on the terminal (very similar to what you see on an M8189 11/23+). From there you select the device-type and unit that you want to boot, and the Arduino sends the bootstrap to the PDP-11 via ODT. If you are interested in this, let me know and I'll send you the Arudino source code. The hardware to be built is very minimal. Here's a screen shot showing the boot menu that the Arudino presents on the terminal -> https://i0.wp.com/avitech.com.au/wp-...1422-Large.jpg

  4. #4

    Default

    I'd love some non-DEC wierdness in my system! I've seen the card on an australian PDP-11/23 clone that was on ebay a while ago, with boot roms installed, so it should work a treat, The pic was just too grainy to make out what the EPROM's were. Hopefully they're not really early EPROM's but it can probably be deduced from the footprint of the sockets.

    Your arduino project sounds really handy too! Though at the moment I'm trying to get it to boot from real disks (floppy, still need an RX50 drive), so an actual rom card would be ideal!
    I've thrown you a PM.

    --Chris

    EDIT: [Actually, I CAN see what they are! they're 2716's!]
    Last edited by Christoffer; October 12th, 2017 at 09:39 AM.


    Current systems: PDP11/23, ZX-spectrum, MEK-6802D5, Ampex 210 CRT terminal, ZX-spectrum
    Current projects: 8085 Altair 8800 compatible
    Looking for: DEC RX-50 drive, QBUS ROM card, intel 8288

  5. #5

    Default

    I managed to find and scan the manual for the this board. I've posted a copy of the manuals, a picture of the PCB, and a ROM dump (taken from another TBC board) here -> http://avitech.com.au/?page_id=2722

    Thanks for the PM. I'll get it posted off to you this week. Let me know how you get on with it.

    Good luck!

  6. #6

    Default

    Thanks a bunch for all your hard work! Once the card arrives I'll try it out with the rom files you've posted. I might also try putting in standard DEC monitors.
    2Kbyte is just enough to boot into tinybasic too!


    Current systems: PDP11/23, ZX-spectrum, MEK-6802D5, Ampex 210 CRT terminal, ZX-spectrum
    Current projects: 8085 Altair 8800 compatible
    Looking for: DEC RX-50 drive, QBUS ROM card, intel 8288

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