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  1. Replies
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    OSI floppy test program

    Don't know what happened with the subject on the previous posting attempt so re-posting.

    I and others were having some problems with our floppy drives. Since I couldn't
    find a diagnostic program...
  2. Thread: i

    by djg
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    i

    I and others were having some problems with our floppy drives. Since I couldn't find a diagnostic program for the Ohio Scientific I wrote one.

    http://www.pdp8online.com/osi/osi-floppy-test.shtml
    ...
  3. Don't have any real information but did a quick...

    Don't have any real information but did a quick search and these look promising.
    https://www.mouser.com/Optoelectronics/Optical-Detectors-and-Sensors/Phototransistors/_/N-6jjuf?P=1yzvx33

    They are...
  4. Thread: EDUSYSTEM-30 cards

    by djg
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    I have played with mark sense on my PDP-8. I used...

    I have played with mark sense on my PDP-8. I used the mark sense batch version of them so don't have direct experience with the edu30 version. I was planning to make some cards for it also but...
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    If you want to send it to me (MD) and pay return...

    If you want to send it to me (MD) and pay return shipping if you want it back I can try reading it with my MFM reader/emulator. Send me a PM.
  6. Thread: DEC flat cables

    by djg
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    DEC flat cables

    Has anyone found a good method for repairing the DEC flat cables? The ones with flat wires with plastic laminated to each side. The glue holding the plastic on fails and you end up with two sheets of...
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    The terminal needs to match how you have your...

    The terminal needs to match how you have your board configured.

    https://homepage.divms.uiowa.edu/~jones/pdp8/hard8e/kl8ja.html

    Same for the disk.cfg. it needs to match how the second board is...
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    There is another way to recover contents of...

    There is another way to recover contents of drives without the original controller. http://www.pdp8online.com/mfm/. Probably overkill for just reading one drive.

    The head positioning is handled by...
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    I have a scan I did here. I'm not sure there is...

    I have a scan I did here. I'm not sure there is such a thing as a clear DEC schematic for the 8/E.

    http://www.pdp8online.com/pdp8cgi/query_docs/view.pl?id=227
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    Yes the IF is used so you have a page 0 in each...

    Yes the IF is used so you have a page 0 in each field. Question 2 your statements are also correct. TAD and DCA are handled the same for addressing.

    This will load 30 into the AC
    1 ...
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    I think you are referring to using a BBG without...

    I think you are referring to using a BBG without my MFM board. If so you might need to drive other signals. If write is active it will overwrite the data. If step is active it will seek etc.
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    It uses all the bytes including the 0xa1.

    It uses all the bytes including the 0xa1.
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    Some sectors use polynomial 0x1021 initial value...

    Some sectors use polynomial 0x1021 initial value 0xffff and the majority use 0xa00805 initial value 0xffffffff. I have images read with my MFM emulator I can check if you need more. The header always...
  14. TI PC. From left to right TI 256k memory, 3 plane...

    TI PC. From left to right TI 256k memory, 3 plane graphics, Seeker 512k memory & SASI interface, CSTI board set. Floppy and video pass through board to allow it to provide IBM compatible interfaces....
  15. I have one we bought new....

    I have one we bought new. http://www.pdp8online.com/shows/vcfe16/pics/P1090151.shtml?small

    It has a CSTI board that adds IBM compatible CGA graphics and BIOS etc. Worked reasonably well but not...
  16. Email djg@pdp8online.com

    Email djg@pdp8online.com
  17. More facets of hard disk recovery (SA1000, RD53) and emulation

    I have made a SA1000 adapter board for my MFM reader emulator. I did a
    small run which seems to work so if you are interested email me to get
    in on the next order. Prices may get a little better if...
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    PAL is a primitive assembler and the instruction...

    PAL is a primitive assembler and the instruction set of a PDP-8 is even more primitive. A lot you can do with later processors is complicated with the PDP-8. The PAL section in Programming Languages...
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    Actually that wasn't quite correct. 0 is device...

    Actually that wasn't quite correct. 0 is device dependent operation not zero records.
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    I think this 0212 4000 4000 /FUNCTION CTRL WD...

    I think this
    0212 4000 4000 /FUNCTION CTRL WD

    Needs to be 4100. You are saying output zero records.

    Some random code that uses TTY...
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    Correct on name. I just linked to the...

    Correct on name. I just linked to the documentation, I didn't do any of the work and I don't have that board set. I do have the DEC version.



    Picture of the board here. Since they seem to be...
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    You may have already seen this. Pricey Plessy...

    You may have already seen this. Pricey Plessy version though best offer available.

    https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=pdp+plessy&_sacat=0

    Schematics here...
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    I've been looking at this some for adding SA1000...

    I've been looking at this some for adding SA1000 support to my emulator. The line drivers use for SA1000 are current source so need resistors to ground. The standard termination for ST506 is 100 ohms...
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    It should have used the sector header information...

    It should have used the sector header information when creating the image file. Some systems do various rearrangement of the data that isn't marked in the headers. It can dump the sector headers with...
  25. Just ran across this. Picture is my machine. Its...

    Just ran across this. Picture is my machine. Its 730x300 pixels vs CGA 640x200. I can measure the video timing if you wish. I have a little info on it online at...
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