They look like expensive versions of the HC-12 modules.

https://www.amazon.com/433Mhz-Wireless-Replace-Bluetooth-Antenna/dp/B0C7M99BQM


On 9/30/2025 9:08 PM, Dave Everett wrote:
Check out the description for these:

https://ebay.us/m/drkr36


Dave

On Wed, 1 Oct 2025 at 11:04, Scott McDonnell <[email protected]> wrote:

    1200 baud seems to be the most reliable. 9600 is possible, though.

    On 9/30/2025 8:50 PM, Dave Everett wrote:
    What was the max baud rate for the m100? I regularly use
    transceiver modules that do ttl rs-232. They run at 9600 but from
    memory that can be changed. I just don’t recall if it can go lower.

    Dave

    On Wed, 1 Oct 2025 at 08:50, Scott McDonnell
    <[email protected]> wrote:

        I plan to dedicate one of my Model 100s to use as a
        controller for my
        80s robots.

        These are my planned mods to implement this:

        1. Internal retro wifi modem (oldnet.com <http://oldnet.com>)

              I plan to make hack onto the MC14412 chip. I have no
        plan to
        retain the original modem functionality, but if I did, I am
        thinking I
        could implement this via the modem enable signal. That would
        also allow
        me to control power to the ESP8266 so that it did not drain
        the battery
        when not in use. I could bring the enable line out to a
        switch to
        reconnect the enable line to the MC14412. At the moment, I
        can't really
        think of why I might ever want the original modem.

        I will use a Wemos D1 mini with an external antenna that I
        will attach
        to the M100 body.

        2. Complete my originally idea to port the TPDDuino project
        to the
        sparkfun openlog hardware and make this internal

             Here, I am thinking the BCR TTL serial mod would be
        appropriate.
        This frees up the serial port which I will need for the robot
        control.
        Not sure if TSDOS already supports this, however. There could
        could be
        some benefits to the faster speed possible with the BCR hack.

        3. Wireless serial

             For this, I have not decided whether to use bluetooth or
        an HC-12
        module. This will be in an external modules so that I can use
        the serial
        port for other purposes. I do plan to add a fused 5V output
        to pin 25 of
        the serial port. This was a common pin to use back in the day
        for adding
        a power output. It doesn't appear to be connected to ground
        in the M100
        per the schematics, but I will need to double-check.

        4. Joystick mod mentioned previously

             If I will be using the BCR port for the TPPDuino, then I
        will end
        up implementing the ideas discussed in that thread for using the
        parallel port. But I also might just hack into the keyboard
        matrix
        arrows since this will be dedicated for this purpose. Still
        weighing
        this while I work on the other mods.

        -----------------------

        Interested in internal battery hacks. I have been thinking of
        installing
        a 7.2V nimh pack. I am not really sure it could fit anywhere
        inside, though.

        While looking through old magazines, I had seen products that
        were
        available at the time which were battery packs that also
        doubled as tilt
        stands. I liked the look of those and might end up 3-D printing
        something like that. There was a simpler project to use a PVC
        pipe with
        D cell batteries and the author fashioned that to also act as
        a tilt stand.

        For my first M100, I had modified a book light to attach to
        the BCR port
        to provide light for the LCD. I wasn't especially happy with
        it as the
        clear plastic bezel is too glossy and reflected too much of
        the light. I
        feel like if there were any possible enhancement here, it
        would need to
        be some sort of front light mounted internally. This is
        probably outside
        of how much effort I want to put into this.

        Interested in hearing about any experience and efforts into
        trying to
        improve the readability of the LCD.

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