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Recent content by mrthreeplates

  1. M

    Supercharging my IBM 5150

    Messed around a bit more today with my 5150 I have further convinced myself that a 8.33 MHz system clock (25 MHz oscillator) is stable. My 5150 passes dozens of passes of the Giller/Black ROM-based ram tests. Even up to 25.9 MHz, I am not getting any RAM errors. Booting GlaBios and my...
  2. M

    Supercharging my IBM 5150

    Success! My 5150 boots & runs at 8.33 MHz, which I'm pretty happy about and seems stable. 10 MHz fails badly. Details below. I discovered that the Picomem f/w (Jan 1st) isn't very happy running at close to 8 MHz. I either get boot hangs or some kind of boot init failure. Once in a while...
  3. M

    Supercharging my IBM 5150

    Continuing my project, I worked on my Lo-tech ram errors next. TLDR: I have been able to find a workaround for the memory failures, details below. I noticed that when I disabled only the first 64K block of the Lo-tech board, with the remaining 9 visible/testable 64K blocks enabled, I didn't...
  4. M

    My floppy remapper project, version 2

    For what it is worth, I am very pleased that "Tucs Workbench" on eBay is offering my remapper boards for sale. Hopefully, this initial programming/testing gotcha is now a thing of the past. It is definitely something to watch out for, should you want to make your own. This is the benefit...
  5. M

    My floppy remapper project, version 2

    So glad it worked and thank you for sharing your tips!!! Best regards,
  6. M

    TRS-80 Model 4 NGA Service Manual

    Sorry, I just have 26-2110, 26-2119, and 26-1080. And I was looking forward to have an excuse to get one of those fancy new book scanners that I see on YouTube.
  7. M

    TRS-80 Model 4 NGA Service Manual

    OK, which manual (name and catalog #) has not yet been scanned and archived? Just asking in case I may have it.
  8. M

    TRS-80 Model 4 NGA Service Manual

    Is the manual in question here the " model 4/4p technical reference manual" 26-2119 ?
  9. M

    My floppy remapper project, version 2

    Great, I will try to help as much as I can. Unless the Pic is damaged, installed incorrectly, or the wrong/fake part, it probably will work after reprogramming. However, I offer no guarantees! And yes, that is the intent of the self-tests. They are designed as a one-time, post-manufacturing...
  10. M

    My floppy remapper project, version 2

    Hi view836, Sorry you are having trouble. I don't think you have done anything wrong. It sounds like both boards are running into a self test failure. See: https://github.com/mrthreeplates/TRS-80_floppy_remapper/blob/master/Design.md When the pic is first programmed, and it boots for the...
  11. M

    Supercharging my IBM 5150

    Hi everyone, This is a continuation of my IBM 5150 restoration / exploration here, having a great time playing with one of my retro projects. Posting this here in case others find this as interesting as I do. My next step is to overclock the 5150. This is nostalgic for me as my first IBM PC...
  12. M

    PicoMEM Project : Pi Pico on an ISA Board.

    I continue to have a lot of fun with my picomem, thanks for all the great work! With regards to a real floppy controller coexisting with one or more virtual picomem floppy images: I am able to get one real floppy and one picomem floppy, but not two of each. I tried setting my 5150's...
  13. M

    Strange PCLK behavior with PC-Sprint on IBM PC 5150

    I'd like to add some more detailed measurements for future reference. I first measured PCLK as generated by the PC-Sprint when in turbo mode (with a 22.x MHz turbo crystal). I expect this to be a solid 2.38Mhz, 50% duty cycle, 420ns cycle time. And it was (see first attachment)...
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