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Type: Posts; User: DougIngraham

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  1. I saw some code a long time ago and came across...

    I saw some code a long time ago and came across one of those things that I have used ever since. In a place where the code gets modified like a computed CDF or the entry point to a subroutine this...
  2. I am guessing you haven't run this yet. CDF 1...

    I am guessing you haven't run this yet. CDF 1 won't do what you want. It is CDF 10 to select field 1. The opcodes are built with a logical or of the individual codes. With CDF the encoding is...
  3. Sounds like you are writing an interpreter. One...

    Sounds like you are writing an interpreter. One of the speed ups I came up with is placing the start of the dispatch routine on page zero. That way you can jump directly there saving 1.2...
  4. Your solution looks good. The rest of this is...

    Your solution looks good. The rest of this is just spit balling ideas. Maybe you will see something in it you didn't think of.

    The first solution that came to mind:

    CLA CLL
    ...
  5. What kind of filter element was used on these? ...

    What kind of filter element was used on these?

    While my rack mount Straight 8 has filters on the intake fans in the bottom of the racks none of my other 8's do. I guess I never saw a non rack...
  6. Is that an intake filter?

    Is that an intake filter?
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    There are only very minor differences between the...

    There are only very minor differences between the DECmates and the other 8's. As long as you do filesystem I/O via the system calls it all pretty much should work. Other languages available are...
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    I've only got one of these in my Straight 8. It...

    I've only got one of these in my Straight 8. It is the cable between the controller and the paper tape punch. In my machine this cable failed due to overheating of the copper on a couple of the...
  9. I discussed this with a friend not too long ago. ...

    I discussed this with a friend not too long ago. Unless the transient goes above 7 volts it should not be a problem for the logic. 7 volts is the absolute max rating. I have run common TTL from...
  10. ISZ is the same on all machines. The specified...

    ISZ is the same on all machines. The specified memory location is incremented and the next instruction is skipped if the result was zero.

    Seems odd that this would have problems if the group 2...
  11. I wrote a paper comparing all of the 8 CPU's a...

    I wrote a paper comparing all of the 8 CPU's a while back. The note says 2010 but I started working on it in the 90's. I'll attach it here. Let me know if you see any mistakes.
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    What was the capacity of the original cells? ...

    What was the capacity of the original cells? NiCd's of the period could be trickled at a C/10 rate without issue.

    Old NiMh cells (pre eneloop type) could be trickled just like NiCd's. The...
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    I wouldn't try to do this. Despite the name, a...

    I wouldn't try to do this. Despite the name, a supercap does not have that much energy storage. And the state of charge is directly proportional to the voltage. To make it work would most likely...
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    Nice going Mike. I've found that having 3...

    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....
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    I would have thought the DEC section would be a...

    I would have thought the DEC section would be a better place for this.

    You should also add the DECSet 8000 which is another re-badged 8/e. Sold as a typesetter for Classified Ads to newspapers.
    ...
  16. Have you got any embedded examples? I can't...

    Have you got any embedded examples? I can't think of anything that used the Harris or Intersil parts other than the DEC PC devices. By this I mean the VT78 and the DECMates.
  17. I am guessing that someone added a zero to the...

    I am guessing that someone added a zero to the number. No way had they sold 450000 in 1978.

    As to how many survive? A few thousand at most and a lot less of those are in running condition. I...
  18. A general purpose XOR takes 10 instructions so...

    A general purpose XOR takes 10 instructions so what you are doing is best for this situation. A specific case takes eight instructions, two constants and two variables.

    DCA TMP1
    ...
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    I think I understand your confusion now. When a...

    I think I understand your confusion now. When a program asks OS/8 to open a file for output it normally finds the largest <EMPTY> directory entry. In another reply I believe I said the first...
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    I am confused. Copying a PDP8 text file can be a...

    I am confused. Copying a PDP8 text file can be a different thing from copying a binary. In today's world DATA is DATA and BITS are BITS (most of the time) but that is not true of these old files...
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    What comes to mind first is that you need the...

    What comes to mind first is that you need the first <EMPTY> block on the file system big enough to hold your output file. Just having enough free space is not enough. OS/8 files must be contiguous....
  22. I plan to do exactly that as soon as I get the...

    I plan to do exactly that as soon as I get the sections on the Serial disk handler included. Kyle gave me permission earlier this week to include/use his sources. The book we are talking about is...
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    What you are seeing is exactly what I would...

    What you are seeing is exactly what I would expect if you did not install the system handler on your boot image.

    The system handler is the part of OS/8 that knows to talk to the serial disk server...
  24. Glad I could help out. I just found my way here...

    Glad I could help out. I just found my way here and signed up. Looking forward to seeing how this project turns out.

    Doug
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