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Thread: Build your own PDP 8I, book

  1. #1
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    Default Build your own PDP 8I, book

    Hi All;
    I just received a book, that I had ordered about a week ago, and it was stated that in it, it had information on building your (my) own PDP 8I..
    Needless to say I figured for the price of this book I could take a chance on it, lets just say I paid more for the Shipping than for the Book..
    And a Quick look thru it and it goes into much Detail about what you would do do Design a PDP 8I, And there are many tables and listings and flow charts..
    And there is enough information in the next Chapter to actually make the machine.. Functionally it says it is the same, it goes about it Differently than DEC did..
    After having looked at the book a little closer, there are parts of Schematics, and many block diagrams and flow charts, and much of it is left to the student to do what is not there explicitly, but the information is there..
    It is part of a course on Digital Design, and looks well written.. I like the style and after I figure some of his logic symbols and methodology, I think it would be a good exercise for me to do at least on Paper.. Supposedly there are about 125 Ic's for the whole design since there is no busing between boards, it would be on one maybe two boards, not counting the front console, with switches and Led's..
    So, what is the title --

    The Art of Digital Design An Introduction to Top Down Design (Second Edition) By Franklin Prosser and David E. Winkel

    Here is a link for a feel of the book.. http://www.cs.indiana.edu/classes/b4...DD-260-271.pdf

    THANK YOU Marty
    Last edited by Marty; March 20th, 2015 at 08:44 AM.

  2. #2
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    The book is available through Amazon for just a few dollars.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

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    Or you can just use an FPGA and Verilog/VHDL. At this point, I find it hard to see the difference between SSI TTL and programmable devices. The thought process, it would seem, would be the same.

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    It much easier to have independent clocks with SSI/MSI. FPGA designs with several clock signals can be hard to get working.
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

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    Hi All;
    Thank You Both for Your comments..
    Chuck, that isn't the same.. Yes, I know I could put it into an FPGA, and Spoil the whole thing !!!!
    I can't look into the FPGA and follow a signal from point A to point B.. And put in a Ton of Led's to watch the Sequencing and the logic flow of each Instruction.. You can't do that with an FPGA !! I have a friend who is an FPGA Guru and from time to time I help him ( hold the scope leads).. So, I know something about FPGA's but not much.. You sound just like what He would say, and to me it's nowhere near the same..
    Just like I know I could Run Simh or put a PDP 11/45 in an FPGA.. But, that's just NOT for me..

    THANK YOU Marty

  6. #6

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    Quote Originally Posted by Marty View Post
    Hi All;
    Thank You Both for Your comments..
    Chuck, that isn't the same.. Yes, I know I could put it into an FPGA, and Spoil the whole thing !!!!
    I can't look into the FPGA and follow a signal from point A to point B.. And put in a Ton of Led's to watch the Sequencing and the logic flow of each Instruction.. You can't do that with an FPGA !! I have a friend who is an FPGA Guru and from time to time I help him ( hold the scope leads).. So, I know something about FPGA's but not much.. You sound just like what He would say, and to me it's nowhere near the same..
    Just like I know I could Run Simh or put a PDP 11/45 in an FPGA.. But, that's just NOT for me..

    THANK YOU Marty
    I agree it can be done, but is not the same (to me anyway). Simh is a nice way to set up a system by configuring it
    since I don't have a tape drive to boot a system to build it on the real hardware. So I do this via Simh and then
    dump to my real pdp-11. I suppose if I didn't have the real thing an FPGA would be better than nothing.

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    I think the PDP-8 core was one of the first complete CPU designs for FPGA--I suspect that there's at least half a dozen out there. I know that there are a couple FPGA PDP-11 designs, which to my way of thinking is a far more usable machine.

    But I can appreciate the desire to put together something from low-level parts. What does the book's design do for I/O?

  8. #8

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    Quote Originally Posted by Chuck(G) View Post
    Or you can just use an FPGA and Verilog/VHDL. At this point, I find it hard to see the difference between SSI TTL and programmable devices. The thought process, it would seem, would be the same.
    An FPGA might be made to act like a PDP8, but it will never be a PDP8 in ways that matter to those who love vintage hardware any more than a Plymouth Prowler will ever be a street rod in the eyes of someone who loves the real deal.

    I'm pretty sure I wouldn't accept the FPGA or the Prowler as a gift. >.<

    Well, maybe the prowler long enough to find some fool to sell it to.

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    Quote Originally Posted by DDS View Post
    An FPGA might be made to act like a PDP8, but it will never be a PDP8 in ways that matter to those who love vintage hardware any more than a Plymouth Prowler will ever be a street rod in the eyes of someone who loves the real deal.

    I'm pretty sure I wouldn't accept the FPGA or the Prowler as a gift. >.<

    Well, maybe the prowler long enough to find some fool to sell it to.

    I love Vintage Hardware but there is no way I will ever be able to afford a real PDP-8, even my SBC6120 was a stretch, but I do like it. I think a a gate level, cycle accurate, implementation of a straight-8 would be something worth having..
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  10. #10
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    Hi All;
    Well, Thank You to everyone for their Input, on this..

    Chuck, Thanks for asking.. "" What does the book's design do for I/O? "" They have a design for a Serial I/O, I think they use a UART, but there is in another chapter a project for doing Your own Parallel to Serial converter..
    I am seeing what IC's I have to start the project off, I will need to make some subs, like the are using 74LS378's or 74LS379's for their enabled registers, and I don't have any, so I will use some 74LS377's instead.. It needs a twelve bit register and the 74LS378 has six in it, so two are needed, and by my using a 74LS377 which has 8 registers, I can use six of these and use two like they will..
    THANK YOU Marty

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