Image Map Image Map
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 27

Thread: Oh dear... 4 bits extra! PDP11/10

  1. #11

    Default

    I'm wondering, in the minimal configuration I can read memory by examining addresses in a normal way...
    But from address 040000 and up the address does not count up any more and the panel freezes.
    I can't even load a new address. I have to press the start button to unfreeze the panel and after
    that I can load a new address. But reading and writing the serial port does work.

    Quote Originally Posted by MattisLind View Post
    A M9301 is easy to check out. Just examine memory at 173000-173776 and 165000-165776.
    There is a small instruction test that test some basic tests in there. Just start at 173000. You can single step through it and see what it does.
    In the meanwhile I fixed the stuck bit caused by the M9301. A bad 7402 was causing this.

    M9301 stuck bit.jpg

    But I can't read that address... And I can't start the monitor program at that address...
    Still some work to do. So back to the basic configuration again...
    WTB: Case for Altair 8800 ...... Rolands Github projects

  2. #12

    Default

    It freeze because of a bus fault. Perfectly normal when acessing non existent memory.

  3. #13

    Default

    Quote Originally Posted by MattisLind View Post
    It freeze because of a bus fault. Perfectly normal when acessing non existent memory.
    Okay great! I already had such a suspicion. Never had a PDP8 to lock up on me for that I tried to examine memory at 173000-173776 and 165000-165776
    for the M9301 like you said. But no response on that too. The same behaviour. To be sure, the ROM contents should be readable
    trough the front panel in this way? Or did I misunderstand your post?
    Last edited by Roland Huisman; July 12th, 2020 at 04:33 AM.
    WTB: Case for Altair 8800 ...... Rolands Github projects

  4. #14

    Default

    The memory should be accessible. A jumper/switch-setting perhaps? I don’t remember details on the M9301. Or there are more issues with your M9301. There are logic in there generating the SSYN signal. Good idea to check that one.

  5. #15

    Default

    Quote Originally Posted by MattisLind View Post
    The memory should be accessible. A jumper/switch-setting perhaps? I donít remember details on the M9301. Or there are more issues with your M9301. There are logic in there generating the SSYN signal. Good idea to check that one.
    Thanks and it is confirmed, the M9301 was still broken! The error was in the addressing circuit
    with a broken SN7420. So two broken chips on one little PCB. But it starts the monitor now!

    Another broken chip 7420.jpg PDP11 Runing monitor.jpg IMG_20200712_152712.jpg

    I thought that should be an @ instead of a $? To be continued...
    WTB: Case for Altair 8800 ...... Rolands Github projects

  6. #16

    Default

    Great! Then many things in the CPU works as it should. I think you should get PDP11GUI and download the basic CPU diagnostics. There are many to choose from. Either the smaller that test just one thing or the one that test everything. But make sure you find the ones that have a matching listing pdf...

  7. #17

    Default

    Nice work! Should be easy from here.

  8. #18

    Default

    Quote Originally Posted by MattisLind View Post
    Great! Then many things in the CPU works as it should. I think you should get PDP11GUI and download the basic CPU diagnostics. There are many to choose from. Either the smaller that test just one thing or the one that test everything. But make sure you find the ones that have a matching listing pdf...
    Yes I have seen that PDP11 GUI, a very nice piece of work!
    So I'm going to check that out somewhere next week.

    Quote Originally Posted by Dare View Post
    Nice work! Should be easy from here.
    Well, it would be nice to know how to wrap that Unibone around the existing hardware.
    I just want to use an emulated RL01 and the 8-56K memory filled up.
    Do you know a document about how to setup the Unibone?

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  9. #19
    Join Date
    Sep 2019
    Location
    Zurich, CH
    Posts
    190

    Default

    Quote Originally Posted by Roland Huisman View Post
    Okay great! I already had such a suspicion. Never had a PDP8 to lock up on me for that
    The PDP-8 do not have a very fancy protocol on a bus to talk to memory like the PDP-11 do. So a PDP-8 can't tell if the memory actually exists or not. You'll get something always, but it might just be floating bus lines.
    The PDP-11 on the other hand have a protocol when accessing anything on the bus, and will have a timeout if there is no response.

  10. #20

    Default

    Well, it would be nice to know how to wrap that Unibone around the existing hardware.
    I just want to use an emulated RL01 and the 8-56K memory filled up.
    Do you know a document about how to setup the Unibone?
    There is a lot of documentation on the RETROCMP site: http://retrocmp.com/projects/unibone

    There are also example scripts available in the github repo: https://github.com/j-hoppe/UniBone/t...5_applications

    Unfortunately I don't have my system in front of me right now so I can't be more specific.

    --Jay

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •