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Thread: PDP-9 at the RICM

  1. #111

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    Quote Originally Posted by m_thompson View Post
    We connected an ASR33 Teletype to the console port on the PDP-9 today. Much more fun than the VT220.
    Fantastic work!

    Really would like to see the DECtapes spinning, the TC02 flickering and the sound of the ASR33 in a video. Please!

  2. #112
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    Maybe we can make a video if it booting tomorrow.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  3. #113

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    Quote Originally Posted by maxfli View Post
    Sounds interesting, look forward to update on the PDP-9. What size space do you currently have and how big is the new space? Look forward to some pictures!!!
    Once the processor is working again, we will connect the TC02 to the I/O bus and see how much of that works. We can repair and test the ancient TU55 on the PDP-8/I before we move it to the PDP-9 so we don't make debugging even more complex. If we can get the TC02/TU55 working we should be able to get a DECtape based OS running. That would be very cool.

  4. #114

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    We connected an ASR33 Teletype to the console port on the PDP-9 today. Much more fun than the VT220.

  5. #115
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    RICM_PDP-9_ADSS-V5A.jpg

    We can boot several versions of ADSS from DECtape, but all of the versions prior to V5A will not run any programs like PIP, or MACRO. The error that it reports says that a device is not ready, and the behavior is the same on SIMH and the PDP-9. Bob Supnik looked into the problem, and said that one of the parameters passed to a routine that checks that devices have been assigned to DAT slots doesn't make sense and causes the error. We were able to boot ADSS V5A yesterday and everything runs OK. Unfortunately with this "new" version of ADSS the DAT assignment for DECtapes for FORTRAN-IV and MACRO are fixed and we need three DECtape drives.

    It looks like the choice is to debug the problem with the earlier versions of ADSS and run with two DECtapes, or use the newer version of ADSS and add a third TU55 to the PDP-9. Since the source code for the newer version of ADSS is available, maybe getting a third TU55 makes sense.

    Another possibility would be to make a 24k memory and KG09 Memory Extension Control emulator from an FPGA. That might be an interesting project...
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  6. #116
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    We added a second TU55 DECtape drive to the PDP-9, and need to add a third in order to use MACROI and F4I. These compilers have fixed I/O device assignments in order to save a little core and run on an 8k machine. Unfortunately the default device assignments are System: DT0, Input: DT1, and Output: DT2 which means three TU55 drives.

    One of our volunteers says that we always need to fix the tools before we can fix what is broken. In this case the DECtape diagnostics would not run, so we could not test the newly added TU55. The second of the instruction tests showed that the RTC was working. A little bit of signal chasing and we found a bad S603 Pulse Amplifier. Replacing the S603 fixed the RTC, fixed a problem where the I/O RESET switch would not clear the interrupt enable flip-flop, and now the instruction test and the TC02/TU55 diag runs. The second TU55 had a bad tape head where one of the coils for the timing track is open. We can't format DECtapes in this drive, but it should otherwise work OK.

    Time to install the third TU55 and polish it's tape guides.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  7. #117

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    Nice going Mike. I've found that having 3 working DECTapes makes for some of the best visual demos of these machines. Pen plotters are a close second and right behind that is high speed paper tape. People like seeing stuff move. Modern computers can paint pictures on a screen in ways we never dreamed of but that is just bits of light. Making stuff move!

    I hope to get out your way sometime in the next year or two.

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

  8. #118
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    Doug,

    We installed the third TU56 yesterday, removed and polished the tape guides, and replaced the Integrating One-Shot. The drive works, but is not 100% reliable yet. Still some work to do.

    We are also collecting flip-chips so we can implement the prewired 34H graphics. If we can find/make the complete set then we will install a Tek RM503 in the top of the CPU cabinet, and then see if we can find the SpaceWar code for the PDP-9. Our visitors really like playing "classic" video games on ancient machines.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  9. #119

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    You may have noticed that one of my DECTapes contains Spacewar! for PDP-9. No source code though.
    Last edited by anders_bzn; December 18th, 2019 at 12:42 AM. Reason: spelling

  10. #120
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    Quote Originally Posted by anders_bzn View Post
    You may have noticed that one of my DECTapes contains Spacewar! for PDP-9. No source code though.
    I started writing a PDP-9 disassembler, so we might be able to reconstruct the source.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

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