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Thread: Teensy 4.0 emulation of a Z80 computer running ZCPR3.3/ZSDOS with GSX colour graphics

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  1. #1
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    Teensy 4.0 emulation of a Z80 computer running ZCPR3.3/ZSDOS with GSX colour graphics

    Over the winter, I'd started a project to take RunCPM and extend it into a complete computer. One with a RTC, serial and parallel port, an ANSI terminal with colour GSX graphics.

    I just heard someone in the back ask Why? Well, it kind of took on a life of its own; sometimes you just get carried away with something. Or it carries you away. And it became something to do whilst we were all confined to our neighbourhoods here.

    And so here it is: the Teensy Board/Z80. Any resemblance to the old Ampro Little Board/Z80 is completely unintentional, I'm sure.

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    The populated Teensy Board/Z80. Why all the thru hole parts? Mostly because I had them on hand. A lot of this project was like that. Why the old first generation Raspberry Pi when a Pi Zero would have been so much more compact? Because I had one sitting around just gathering dust!

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    In its case with the rPi that's the ANSI terminal.

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    It's alive!

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    Yes, that's a daisywheel printer. And a modem on the serial port. Granted, it's a WiFi modem, but it looks the part.

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    Despite sitting in a closet for most of the past 30 years, the printer still works. And you can still get ribbons for it.

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    And if I can't actually be out in the kayak, at least I can see it on my "35 years too late" computer.

    And yes, it's completely impractical and out of date. But it's been a lot of fun to tinker with and get going. Watching Turbo Pascal or Wordstar 4 load in the blink of an eye is oddly enjoyable!
    Last edited by Silverlock; 06-24-2020 at 07:01 AM.

  2. #2
    Senior Member+ defragster's Avatar
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    Nice work - seems there was a post back some time that this was under way - good job finishing it

    ... it wasn't too long ago - it seems I had a T_4.1 beta board and noticed there may not be room to add it - though swapping out the SD card would buy some room - but point the wrong way and maybe hit the battery - and it had 8 MB RAM and 16MB of Flash onboard too. And with USB_Host you could add a wireless mouse and keyboard.

  3. #3
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    If I was doing this again with the T4.1, I'd probably rotate the battery holder 90 degrees and put it as close to the LS245 and 23017 as possible. The T4.1 ought to fit underneath it (from the perspective of looking straight down on the board) and there'd be lots of room to slide the uSD card out. And if that didn't work, I could try a horizontal rather than a vertical coin cell holder and see if I could just slide the uSD over top of the battery.

    A mouse is a possibility even with the current setup. There's a spare USB port on the rPi that's acting as the terminal, and mouse support in the uspi library that's already handling the keyboard. I could create an escape sequence to encapsulate the mouse data and just send it back through the terminal's serial port to the Teensy. There's already a state machine on the keyboard input (to convert VT100/ANSI escape sequences to WordStar sequences) and adding one more filter to capture the mouse sequence and send that elsewhere would be trivial. I just haven't come up with anything I'd need if for yet.

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