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Type: Posts; User: Dwight Elvey

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  1. Replies
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    It is unlikely the pots problem. It is more...

    It is unlikely the pots problem. It is more likely that the sync signal is no getting to the multivibrator. The fact that you are able to get the adjustment to bring the horizontal to the correct...
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    I don't recall if someone posted a pointer to the...

    I don't recall if someone posted a pointer to the video card so here it is:
    http://retro.hansotten.nl/uploads/files/RM%2065%20CRT%20Controller.pdf
    Dwight
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    The machine I have, used the Euro Cards but all...

    The machine I have, used the Euro Cards but all of the boards were made available in both types. The cards with the E at the end were Euro card types and the ones without the E at the end were the...
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    The RM65 cards also came with an edge connector...

    The RM65 cards also came with an edge connector as well as the Euro type connector. It is just as valid and a lot easier to deal with. You might also look at using a bus rather than a single...
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    The video card manual is on the web someplace....

    The video card manual is on the web someplace. The cards were made in a Euro card like format and a STD bus like card. Neither cards were compatible with either.
    The interface was mostly buffers as...
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    If it is that black rubber foam, that is not good...

    If it is that black rubber foam, that is not good stuff. At some point the rubber will break down and rot the leads. The best way is to wrap them in foil.
    Dwight
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    We all know there are differences in the flags....

    We all know there are differences in the flags. Still, none of the test to that point had tested that difference. It looked good for a short time, until the flag issue was found. It is also clear...
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    Other than the instruction set, the design of the...

    Other than the instruction set, the design of the Z80 was not an exact copy of the 8080. There is no question that Faggin copied a lot of the main ideas, after all, he was involved in much of the...
  9. Diodes are not linear devices. The voltage drop...

    Diodes are not linear devices. The voltage drop is about 0.65V for a reasonable current. For a 1N4148 that would be in the ma range. Hopefully, the diode is only dropping a few tens of micro volts or...
  10. I'm curious as to how one get N* dos to run on a...

    I'm curious as to how one get N* dos to run on a S100. Does the N* have firmware on the mother board or is that just for I/O and the disk controller does the boot?
    I have a N* but I've not done much...
  11. One can tell if there is a short on the power...

    One can tell if there is a short on the power line but you may not be able to identify which one. Don't depend on beeping as an indication of being shorted. Use an ohms scale and measure it! The...
  12. Not all drive will damage the platters but some...

    Not all drive will damage the platters but some have a sharp edge on the back and will cut a chunk of the platter out. You'd need to replace the platters from a donor drive. The cut will cause the...
  13. 6V may be too high. The original battery was...

    6V may be too high. The original battery was likely a 4.8V NiCad, not 6V.
    Dwight
  14. This would require removing the fragile plastic...

    This would require removing the fragile plastic bezel. That is what is trying to be avoided.
    Dwight
  15. I like the idea of small triangle gussets. Dwight

    I like the idea of small triangle gussets.
    Dwight
  16. Use JB weld. Use the slow setting, not the quick...

    Use JB weld. Use the slow setting, not the quick setting. You may need to grind the ends of the mounts to get them through the ripped metal. Wipe all the surfaces with a paper towel wetted with...
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    I think the disk is to be used with a Diablo 30...

    I think the disk is to be used with a Diablo 30 or 31 drive. I believe the 8008 card should work but it won't run 8080 code. I can't read the EPROM labels but they should be 1702As. Does your 8080...
  18. My experience with Convergent was playing rats....

    My experience with Convergent was playing rats. I'd put a version of Fig-Forth on it to work on the wire bonding hardware we made for wire overflow. I recall the box had several Multibus slots. I...
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    It could be cross talk with another address or a...

    It could be cross talk with another address or a timing issue with the write and address.
    If you swap the RAMs around and it stays at the same location, it is not likely the RAM itself that is bad....
  20. Regardless of the changing, the lamination inside...

    Regardless of the changing, the lamination inside has become separated. I would suspect it will grow over time as it may not yet have an actual leak at the edge. It may be that the backing is bent,...
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    Hugo, your post has made me smile. Knowledge of...

    Hugo, your post has made me smile. Knowledge of these various side things related to electronics has been a great boost to this MB. Rewinding a primary is not the same as rewinding a low voltage...
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    Thanks Chuck That makes some sense. I suspect...

    Thanks Chuck
    That makes some sense. I suspect it increased the inductive phase shift a lot though. I like the idea of re-purposing a microwave oven transformer. It is about the right size ( maybe a...
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    I'm curious, what is the magnetic shunt for in...

    I'm curious, what is the magnetic shunt for in the original transformer?
    Dwight
  24. One of two things. Either it was bitbanging the...

    One of two things. Either it was bitbanging the wire connection or there was an active device in the wire module.
    Dwight
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    It could be the VRAM or the bus buffers to VRAM....

    It could be the VRAM or the bus buffers to VRAM. Is it consistent or does it change each time you reset?
    If it is consistent, does it change when swapping the VRAMs around?
    Dwight
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