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Thread: Unique S-100 computer (Z-80/Vector Graphic/Micropolis)

  1. #51

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    20200303_090729.jpg

    Yes the keyboard is a Key Tronic. I haven't quite figured out how to open the keyboard section of the case yet..

    I've run a partial memory test and got no errors. I'm going to get the expansion board in there and run a full test.

    Haven't opened the disk drive yet or plugged in - so I'm not sure what that situation looks like yet. Thank you & yes if you have a spare please PM & let me know what you'd want for the FDC & box of floppies. Thanks for all this great info! lots to research..

  2. #52
    Join Date
    Dec 2005
    Location
    Toronto ON Canada
    Posts
    7,339

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    Unless I missed mention of it Mike is being modest; there's a Virtual Sector Generator available that lets you use the much more common soft sector disks.

    On a related topic, although Chuck seem to like them I haven't been too happy with the Micropolis drives either so, as in Mike's suggestion to use 55-GFRs, I tried replacing my Micropolis drives with more common Panasonic 5 1/4 1.2M HD drives. Works fine reading and writing, but for some reason it won't boot from them. Could it be related to the fact that the boot track is read by the monitor whereas subsequent reads are by the OS? Any thoughts?

    I haven't tried checking/tuning the timing adjustments on the FDC; any thoughts on that?

    TIA

  3. #53

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    I recall the hard sector controllers are finicky with newer disks drives for which the index pulse outputs are generated by a smart LSI chip. The most important thing is that jumper E2 must be installed to ensure sector pulses are not turned off while the drive is seeking.

    Itís always a good thing to properly adjust the three pots on those boards. Itís fairly straight forward from what I recall.

    Mike

  4. #54

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    Quote Originally Posted by nullvalue View Post
    I had previously installed the 22uf cap (#49) and it has not made a difference. I currently have it disconnected.
    #13 talks about adding a 390pf cap on the Z80 to fix MWRITE issues. This is not installed. Think it's worth bothering with?
    MZ-0018 describes my problem exactly and talks about replacing the crystal. However it looks like I have one of the unaffected model crystals. Should I try replacing it anyway? It also mentions installing that 22uF cap which didn't help.
    Update on the garbled text power-on screen. I added the 390pf cap and reattached the 22uf cap and the system acts MUCH better. Goes right to the monitor most of the time on the first power-on now, if not the second.. before I'd have to flip the switch 10-20 times before it'd finally get to the monitor.

  5. #55
    Join Date
    Oct 2016
    Location
    Dutchess County, New York, USA
    Posts
    118

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    What does the keyboard plug into inside the main rack? Is it one of the parallel ports or maybe a serial port?
    Crazy old guy with a basement full of Pentium 1 laptops and parts

  6. #56

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    Quote Originally Posted by DeltaDon View Post
    What does the keyboard plug into inside the main rack? Is it one of the parallel ports or maybe a serial port?
    20200304_093303.jpg

    It is parallel. The keyboard plugs into this little board (pictured) that sits in the bottom of the case. Then from there, it plugs into the Flashwriter II board.

  7. #57

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    Interesting, they're using the EPROM to translate the output of their custom keyboard to values that the VG monitor and software expect. You'll want to dump that EPROM so you have its content archived.

    I did something similar to connect a keypad in an SD systems computer to a VG FlashWriter, but it was a simple connection re-wiring - no translation of codes or EPROM required.

    Picture2 012.jpg

  8. #58

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    Quote Originally Posted by deramp5113 View Post
    Interesting, they're using the EPROM to translate the output of their custom keyboard to values that the VG monitor and software expect. You'll want to dump that EPROM so you have its content archived.
    I thought it was odd, too. The keyboard is dated 1975 so it was already a bit old when this computer was built (1979 or 1980).

    That EPROM is another 2708. What kind of equipment would I need to dump it? I've already discovered the TL866 doesn't support the 2708.

  9. #59

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    Quote Originally Posted by nullvalue View Post
    That EPROM is another 2708. What kind of equipment would I need to dump it? I've already discovered the TL866 doesn't support the 2708.
    How about one of the ten unused 2708 sockets on your PROM/RAM board

    Mike

  10. #60
    Join Date
    Dec 2005
    Location
    Toronto ON Canada
    Posts
    7,339

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    Quote Originally Posted by deramp5113 View Post
    I recall the hard sector controllers are finicky with newer disks drives for which the index pulse outputs are generated by a smart LSI chip. The most important thing is that jumper E2 must be installed to ensure sector pulses are not turned off while the drive is seeking.

    It’s always a good thing to properly adjust the three pots on those boards. It’s fairly straight forward from what I recall.

    Mike
    Will do; thanks for the tips!

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