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Thread: 8087 on 8088 motherboard that have no socket for it

  1. #11
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    Quote Originally Posted by soviet9922 View Post
    This are the only pictures i can find of the original module intel released when the 8087 was new to upgrade previous systems.

    well I looked at the pic and did a google on the intel part number from pcb being PWA 142696.

    I got a hit of a Russian, I think, saying he has "INTEL CIRCUIT BOARD PWA 142696 REV
    Gold ic 13340048
    I HAVE SEVERAL OF THESE BOARDS
    AND MANY OTHER RELATED IC CHIPS AND BOARDS SO CHECK MY OTHER AUCTIONS"

    its in the text at right had lower at the following web address http://buynowus.com/ebay/list/item?o...=391008831085/

    Maybe some else on here can better read that listing and ask him if he still has any. IF so I would really be interested in one.

  2. #12
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    Lightbulb iSBC 337 Multimodule NDP board for intel 8087

    Have a look at this link

    seems the pic of the intel coprocessor board PWA 142969 leads to this doc. sadly its a text doc and no pics. MAYBE someone has hard copy or a PDF of it

    https://archive.org/stream/bitsavers...Nov80_djvu.txt


    I see the following mentioned in the text

    1-2. DESCRIPTION

    The iSBC 337 Multimodule NDP board (figure 1-1) is
    based on the 8087 Numeric Data Processor. The 8087
    provides powerful arithmetic operations on seven
    different data types including single and double
    precision floating point numbers, words, short and
    long int^ers, BCD format, and internal file precision.



    The co-processor interface of the 8087 to the 8086/
    8088 CPU allows concurrent operation of the two
    processors firom a single inclusion of the 8087 on
    single board computers via the iSBC 337 Multi-
    module NDP board, which is simply a plug on
    option. The iSBC 337 MNDP board can also be
    utilized by other 8086/8088 based designs, due to the
    unique characteristics of the co-processor and Multi-
    module interface.



    1-3. EQUIPMENT SUPPLIED

    The following is suppHed with the iSBC 337 Multi-
    module NDP Board.

    Schematic Diagram, dwg. no. 142698.

    Figure 5-2. iSBC 337™ Board Schematic Diagram (sheet 1 of 1)

    here is the pdf link below.. [ Edited to comment ""actually see my next post with further info""]

    http://www.nj7p.org/Manuals/PDFs/Intel/142887-001.pdf
    Last edited by inotarobot; October 26th, 2016 at 03:21 AM.

  3. #13
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    Quote Originally Posted by soviet9922 View Post
    This are the only pictures i can find of the original module intel released when the 8087 was new to upgrade previous systems.

    99% certain this is the above pictured module layout, circuit and document in the pdf per link below



    and manual http://www.nj7p.org/Manuals/PDFs/Intel/142887-001.pdf

    enjoy and hope someone can easily do a circuit board of same.

    Guess there can be two board options depending on which side of processor, one can fit the 8087 onto, depending on the machine one wishes to add the 8987 co-processor to.

    3rd option is a stacking arrangement. Seems most pins are 1 to 1 connection except on 8087 pins 31 goes to pin 30 on the processor and 8087 pin 33 goes to a connector P2-2 called RQ/GR1A what ever that is.

    anyways I think I have done enough for now, so off to bed for me.
    Last edited by inotarobot; October 26th, 2016 at 03:22 AM.

  4. #14

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    I'm trying to remember what magazine it was, my google-fu is failing me... but aren't they so pin-to-pin that you can just piggy back them and only wire one pin different? Could have sworn I had a XT clone that actually came that way with the two literally soldered one atop the other.

    -- edit -- actually, @inotarobot's post the circuit diagram shows that whilst there are more than one pin, that's basically all we're talking. That should be all the information you'd need to make a board for it.

    Half tempted to try that with my Jr, but my Parkinsons is too far along for me to try that, as my attempt at a 512k conversion to a 128k board is proving.
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  5. #15
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    Thank you very much, this information is great and also that shematic confirm that is just a wire job to get this working.
    Have to purchase a pair of 8087 on ebay to do some testing now.

  6. #16

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    This reminds me of floating point exceptions. At least with the original PC it was a fairly simple connection using NMI. Unfortunately the PCjr uses the same NMI for the keyboard.

  7. #17
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    got a 8087-1 for 7 usd when it arrives gonna build this shematic.

  8. #18

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    ...and how did it go?

  9. #19

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    Awakening this old thread yet again.
    Seems to me that the trickiest thing about adding an 8087 where there is no socket for it, is that you need to know (1) how to connect the INT output from 8087 ultimately to the NMI input of the 8088. If you don't have a valid schematic (or have a sense of the way it works) then ... thats a problem.
    Also, doesn't either BIOS or DOS have to properly handle this NMI input as well?

    More research needed....

  10. #20
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    Quote Originally Posted by Twospruces View Post
    Awakening this old thread yet again.
    Seems to me that the trickiest thing about adding an 8087 where there is no socket for it, is that you need to know (1) how to connect the INT output from 8087 ultimately to the NMI input of the 8088. If you don't have a valid schematic (or have a sense of the way it works) then ... thats a problem.
    Also, doesn't either BIOS or DOS have to properly handle this NMI input as well?

    More research needed....
    The connection is well documented so adding a board should be relatively easy.

    DOS and BIOS don't do anything to handle the NMI. Careless 8087 programming is an excellent method of locking a system.

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