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Thread: Seeking memory card for InBoard/386

  1. #11

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    Quote Originally Posted by H-A-L-9000 View Post
    Is there a good photo of this inboard and its memory expansion available somewhere? Maybe a memory controller could be identified which has a datasheet.
    Go to eBay, search on Completed Listings and use Intel Inboard as the search string.

    Mike

  2. #12

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    Quote Originally Posted by H-A-L-9000 View Post
    Is there a good photo of this inboard and its memory expansion available somewhere? Maybe a memory controller could be identified which has a datasheet.
    The Inboard utilizes PALs and TTL-logic to implement the memory controller.

  3. #13
    Join Date
    Aug 2009
    Location
    Bavaria / Germany
    Posts
    120

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    I'd suggest you write a little program that does nothing more than switch to protected mode and continuously writes RAM addresses at the 1M/2M/4M locations.
    I.e.:
    - write byte at 0x0
    - write byte at 0x1
    - write byte at 0x2
    - write byte at 0x3
    - write byte at 1M+0x0
    - write byte at 1M+0x1
    - write byte at 1M+0x2
    - write byte at 1M+0x3
    - write byte at 2M+0x0
    - write byte at 2M+0x1
    - write byte at 2M+0x2
    - write byte at 2M+0x3
    - ...
    - start over

    Why writes? Because the memory is read all the time for code fetches, but you can filter these out by watching the /WE pin.
    Then you can use your analyzer to check what all the signals do at these addresses, if accesses happen at all on all locations and how they differ.

    If the memory controller is configurable by the BIOS the usefulness of this method is limited - but maybe that's not the case.

  4. #14

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    Quote Originally Posted by H-A-L-9000 View Post
    I'd suggest you write a little program that does nothing more than switch to protected mode and continuously writes RAM addresses at the ...
    Then you can use your analyzer to check what all the signals do at these addresses, if accesses happen at all on all locations and how they differ.

    If the memory controller is configurable by the BIOS the usefulness of this method is limited - but maybe that's not the case.
    I would if i could... i apparently fried my inboard somehow.
    I suspect that i accidentally shorted a pin somewhere and destroyed a PAL.
    Because of that, i am looking for a replacement inboard 386/PC and will pay a reasonable price.

    The 2nd Inboard i have acquired seems to be defective as well...

    Jonas

  5. #15

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    Wellll....I received the new Inboard 386/PC today and installed it. It replaces an InBoard 386/PC that had only 1MB of RAM on board. I THOUGHT the new card had a 2MB piggyback daughter card, I was mistaken. It actually came with a math co-processsor installed and the memory was not 2MB, it is a 4MB piggyback daughter card. I thought the 2MB daughter cards were rare....not sure but I think the 4MB daughter cards are ultra rare. I'm not complaining

    Looks like I'll be selling the 1MB Inboard/386 PC soon! I am not sure what it should go for as the eBay prices have been swinging wildly on this one. The last one that was up there just sold and they sometimes don't materialize for up to 2 years - even the 1MB versions. The 1MB I plan to sell has everything, the original SW, cable, manual, accessories and box and has been fully tested. Anyone have a clue what it should sell for on eBay?

    Regards,
    Mike

  6. #16

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    Im interested... name your price

  7. #17

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    Quote Originally Posted by stynx View Post
    Im interested... name your price
    email me this user name at hotmail.

  8. #18
    Join Date
    Jan 2008
    Location
    70 Miles NW of Melbourne, Australia
    Posts
    613

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    Necroposting I know, however, we still don’t have a replacement for the InBoards 4MB daughterboard. Once we have a schematic for the original 4MB board, a new board with contemporary parts will likely have a significant lower chip count. I believe that a 16MB daughterboard is also a possibility.

    Incidentally, an InBoard with the 4MB daughterboard sold for $1500 on eBay yesterday.
    My Wish List: Vintage Mac SCSI->ETHERNET DaynaPORT LINK T DP0801 Manual, Make-It 486 (or other) 80286 upgrades, Hallock Systems gear / disk images, Copy II PC 'Enhanced' Option Board, Earth Computers ISA Z80 cards & TurboDOS disk. TRS-80 Model IV TurboDOS, Pulsar Little Big Board gear, Tandy Videotext Information System (VIS) for Model 16 Xenix

  9. #19

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    I watched that auction even though I wasn't bidding as I already have the 4MB daughter card. The bids on the pair were very low until the very end, then <pow!> wow! $1500. But those 4MB daughter cards rarely come up on eBay maybe once every few years, and the 4M even less so than the 2MB daughter card, so I guess that demonstrates the fundamental rule of supply and demand. Given the 4MB board is required to run Win 3.1 well with the InBoard 386 it is highly desirable. As was mentioned earlier and in other threads, the stock InBoard 386 rund at 16MHz and tops out at 33MHz with a 486 CPU upgrade unless the oscillator on the Inboard is also replaced. I simply replaced the 386 CPU with a CyrixCx486DRx2 20/40MHz CPU like this one: https://www.ebay.com/itm/Cyrix-Cx486...oAAOSwl9xeE8di It's an easy drop-in replacement and makes the system fly, although that Cyrix only provides a 1MB cache - still happy with it.
    Last edited by nc_mike; January 20th, 2020 at 02:52 PM.

  10. #20

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    I was watching that one as well. The crazy part about that is that there was a brand new one still in the shrink wrap on buy it now for $700: https://rover.ebay.com/rover/0/0/0?m...2F254444805690
    Once upon a time, the internet sucked because it came through the phone. Now the phone sucks because it comes through the internet.

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