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View Poll Results: What would people like to see for the Talker/80 project?

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  • Add speaker + amplifier to board - for cassette output sound + speak

    9 69.23%
  • Add more features - for example, PCM sound, Real Time Clock, ...

    4 30.77%
  • Make it a cartridge that plugs into a back plane extender board

    2 15.38%
  • Make it compatible with the Model 3 / Model 4

    12 92.31%
  • Make a case / enclosure for it (3D printed)

    6 46.15%
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Thread: Talker/80 - New Voice Synthesizer in the Making

  1. #1

    Default Talker/80 - New Voice Synthesizer in the Making

    Work in progress. So far, a first version of the PCB was designed. I plugs into the Model 1 expansion port via a cable, and passes the edge connector through. It is basically a re-iteration / port of a previous speech synth for the Amstrad CPC (LambdaSpeak 1.99). I'll call it Talker/80 for now - to stay away from any TRS and Tandy in the name. I'll also skip prototyping / bread boarding this time given that I have made a lot of these for the Amstrad CPC, and will make the firmware once I have the hardware built. Let's see how this goes. Will probably need more than one iteration of the PCB. I'll start with DECtalk native mode. Next, I will also attempt VS100 and TRS Voice Synthesizer emulation. DECtalk should be a no brainer - not so sure about the emulations though.


  2. #2


    Forgot the configuration DIP switch. Added.

  3. #3


    First PCB version got sent to OshPark today for a first run.
    The design uses:
    - 2x GAL22V10
    - ATmega 644 @ 20 MHz AVR
    - LM741 Opamp for mixing (TRS audio output + speech synth output)
    - Text to speech click board from MikroElektronika:
    - and some resistors, capacitors etc.

  4. #4


    Here is a small update - progress report: admittedly, it was kind of a bold move to not do any bread boarding this time, and go to PCB production right away. Would my design actually work? Now, 3 prototyping PCBs at OshPark for Talker/80 is 65 $, not a huge amount of money, but still!

    The only aspect of the design that really worried me was the address decoding and databus latching and "ready signal" requiring tri-state logic - given that the Model 1 expansion port is notoriously known for being shaky... and add the Expansion Interface to the mix, and everything would break down??

    Happy to say that my experiment confirmed that the two 22V10B GALs will do the job just fine - IO address decoding, memory bus snooping, databus byte latching, and presenting bit 7 and bit 6 to the databus if needed (IN / IOREQ INPUT for the speech synth READY signal) works like a charm, even with the Expansion Interface.

    Now, I have a whole box of these 22V10B's that I got for 20 $ on Ebay - glad I can finally use them for something!!

    So, given that this part of the design works, the rest should work out as well. Phhhw, that's a relief!! With a little bit of luck, this might come together sooner than later.


  5. #5


    A first version is working - here is a short demo video showing it in action:

    Next, I am going to work on implementing the TRS and VS100 emulations. The demo shows the "native" mode of the Talker80, which is DECtalk-based. The DECtalk / Epson firmware does text to speech directly, no phoneme conversion required.

    So, no roadblocks so far - my PCB should work as planned.

    Last edited by LambdaMikel; March 14th, 2020 at 12:52 AM.

  6. #6


    Very nice! Looking forward to seeing more.

  7. #7


    Quote Originally Posted by Alphasite View Post
    Very nice! Looking forward to seeing more.
    Thanks! I am planning to make the final product available at some point. From a hardware point of view, the product is almost finished. I still want to add the amplifier and speaker. Then people can also plug in the cassette sound, and it will get mixed and amplified with the speech. I have a whole box of little speakers sitting here (20 or so) which I got as a bargain on Ebay at some point. They also make great replacements for internal speakers of old computers (e.g., CPC etc.)

    I also tested the video memory snooping / memory mapped interface of Talker-80 by now. Works reliably as well, but only if connected directly to the Model 1 expansion edge connector.

    Anybody knows why the Expansion Interface does not pass MEMRD and MEMWR through? I guess because they thought the Memory is already maxed out anyway with the EI, so no need to pass it through? Hmm..

    This is why Talker-80 has to be connected directly to the Model 1 if the TRS Voice Synthesizer is to be emulated (for native or VS100 emulation, it can be connected to the EI instead). For that reason, my PCB has an expansion port pass through connector, and I hope it will work... this is the only aspect I cannot test without the PCB really. Must say that my EI has never given me any trouble with electric connection or reliability so far. But it is the revised version.

    So, PCB should arrive end of next week, then I will know if the expansion port pass through will work.

  8. #8


    Project Update:

    The PCBs arrived today - and worked out of the box! Pictures attached. The EI works without problems from the edge connector pass through.

    There are still a couple of things I'd like to change:
    - the Model 1 IDC connector should go on the backside... it gets into the way of the audio cable.
    - add the amplifier and speaker option. Currently, it has an LM741 OP Amp that mixes the cassette cable sound and speech synthesizer output. I'll leave that, but also add an audio amp and speaker.

    The bigger outstanding work is with the firmware and the RS and VS100 emulations. But glad that everything works as planned so far.

    DSC09720 - Kopie.JPG
    DSC09721 - Kopie.JPG
    DSC09723 - Kopie.JPG

  9. #9


    the voice sounds almost like the departed Stephen Hawking voice nice, when you get it going for a model 3 or 4 I will extremely interested
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  10. #10


    Quote Originally Posted by Patrick Bureau View Post
    the voice sounds almost like the departed Stephen Hawking voice nice, when you get it going for a model 3 or 4 I will extremely interested
    Right, AFAIK, the Hawking Voice Synth at least has some overlap with DECtalk, which is what you are hearing here.

    Model 3 / 4... just read the IO port description. It is different from Model 1. In particular, we have the ~IOSEL line there which has to be generated by the hardware extension for input IOREQ (IN) (a simple NAND between IO address decoder and IN). And memory mapped IO is not possible, as we all know.

    The VS100 emulation should be possible. But it seems it will be a different device than the Model 1 version.

    Personally, I only own a Model 1 and a Model 4. Model 4 I will support sooner or later, no doubt about it.


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