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Recent content by Dwight Elvey

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    I decided to take a few steps back and decided to create a 80188 CPU computer instead

    I just thought they all had it. It was with the RIM and SIM instructions as I recall. That could be wrong as well, after all I tend to have brain fade. Dwight
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    I decided to take a few steps back and decided to create a 80188 CPU computer instead

    Why do you need a USRT, The 80188 has a serial in and out. If you used a 5V one from a USB converter, you can talk to is from a laptop or such. ( might need an inverter but don't recall). Someplace, I may still have a Forth for the 80188/186, with serial implemented. It has been some time so I'd...
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    Please save these Polymorphic machines

    The video cards work OK with many monitors but there was a timing error in the design. I forget where but I think it had to do with the vertical blanking period. It has been a while since I looked at it. I know it caused problems with some monitors, on the first line. One hopes they copied the...
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    "Vintage Homebrew" section for the forum?

    You mean my 4004 project that was only from, a text description wouldn't count? :( Dwight
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    Seagate ST-251 MFM HD problem

    The original stiction problem was that the surfaces were too smooth. Van Der Waal attraction but your drive could have been lube. Dwight
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    Is there a way to test a logic gate in-circuit without removing it?

    Why solder a chip to the board when you could use a socket instead. Dwight
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    Intel Intellec MDS 80

    It has been too long since I worked on this stuff. You're best bet is to find some boards to swap out. At least that way you could isolate which board was the issue. Dwight
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    I suspect it needs the external module that is used for one of the other applications ( I forget which ). It is great that we finally have someone willing to do a dump. They have called this the information period. I've always called it the information lost period. Dwight
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    UVP DE-4 EPROM Erasing System, still works after all these years!

    That first lamp was originally design for UV light for things like rocks. It also came with a removable filter the use the less high energy UV light. Of course, the UV light through the filter would likely do little for erasing EPRMs. I'm not at all surprised that it still works. The lamps will...
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    KIM AIM SYM eprom programmer card

    I'm made good progress on the programmer card. I wanted to use it on my SYM-2 orSYM-1. It had a EPROM on it that was clearly for an AIM65. I'd assumed it was code to run the programmer. It clearly isn't. First the EPROM is a 2732. I see that pin 21 is hard tied to VCC, as would be typical for a...
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    Thanks How much did the entire set go for?
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    6502 branch at page boundaries

    I also have a SYM-1.It fully decodes the RAM address. Like most 6502 ROM setups it does doubly decodes parts of the ROM to the reset vectors. There is no funny business there. I see no valid reason to have the RAM decoded at all addresses other than that specific to ROM or I/O. I especially...
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    6502 branch at page boundaries

    I have a need to use some of that map for other things through the E connector. One chip is enough to correct it. Dwight
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    6502 branch at page boundaries

    The SYM2 was intended to be a less expansive version of the SYM1. It is clearly not as flexible as the SYM1. The board I have is likely an early prototype. It has some ugly design errors that keep it from being useful for my intended purposes. It does boot and run the monitor. The major issue I...
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    6502 branch at page boundaries

    Thanks guys. I knew there was something but got it all wrong ( too many years ). Dwight