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Thread: Replica Votrax Type "N Talk project

  1. #1

    Default Replica Votrax Type "N Talk project

    The Votrax Type 'N Talk is a 6802 mini computer. I have just published an article on how one was replicated (an interesting challenge from web photographs) and how it can be used to construct the phoneme strings to help program the Hero Jr Robot. It may be of interest to those who use the SC-01A speech synthesizer IC, or who have this Robot or the original TNT unit:

    http://worldphaco.com/uploads/VOTRAX...TS_HERO_JR.pdf

    Also the article contains some information on disassembling and then re-assembling ROM .bin files.

  2. #2

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    I got a slightly different text-2-speech box using the same chip. Mine is the later Microvox talker, which also contains a dictionary with words and phonemes in ROM. I can try to make out a list if you are interested!

    One thing thing this unit has, which is not in the Votrax box, is a clock-divider on the clock line going to the SC-01A, enabling it to be pitched even more around than what is intended. The box can also beep at a selection of tones, since an IO line is mixed into the output amp.
    Current systems owned by me:
    Vintage:IBM PC/XT submodel 087 ( 1983 ), [Kon]tiki-100 rev. C (1983), Compaq Portable I ( 1984 ), IBM PC/XT submodel 078 ( 1985 ), IBM PC/XT286 ( ~1986 ), 3x Nintendo Entertainement Systems ( 1987 ).
    Obsolete:Commodore A500 ( ~1990 ), IBM PS/2 model 70/386 type 8570-161 ( 1991 ), Atari Lynx II ( ~1992 ), Generic Intel 486SX PC ( ~1993 ), AT/T Globalyst Pentium w/FDIV bug MB ( 1994 ), Compaq 486DX4 laptop ( ~1995 ).

  3. #3

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    Quote Originally Posted by per View Post
    I got a slightly different text-2-speech box using the same chip. Mine is the later Microvox talker, which also contains a dictionary with words and phonemes in ROM. I can try to make out a list if you are interested!
    Yes, I would be interested to see how they did it in that unit, thanks,
    Hugo

  4. #4

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    This is the part of the ROM that contains the dictionary. It's coded sequentially, every entry consist of a series of bytes with the most significant bit cleared, followed by a sequence of corresponding phonetic codes with the most significant bit set.

    I have a theory that it searches through the list, using groups of adjacent printable ASCII characters as key. Non-printable ASCII characters are probably used as flags, for example for what operating mode an entry is valid for. Bit 6 in the phonetic bytes is also probably a flag, possibly used to store information about inflection.

    The schematics and instruction manual for this is on Archive.org: https://archive.org/details/Microvox
    Attached Files Attached Files
    Current systems owned by me:
    Vintage:IBM PC/XT submodel 087 ( 1983 ), [Kon]tiki-100 rev. C (1983), Compaq Portable I ( 1984 ), IBM PC/XT submodel 078 ( 1985 ), IBM PC/XT286 ( ~1986 ), 3x Nintendo Entertainement Systems ( 1987 ).
    Obsolete:Commodore A500 ( ~1990 ), IBM PS/2 model 70/386 type 8570-161 ( 1991 ), Atari Lynx II ( ~1992 ), Generic Intel 486SX PC ( ~1993 ), AT/T Globalyst Pentium w/FDIV bug MB ( 1994 ), Compaq 486DX4 laptop ( ~1995 ).

  5. #5

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    Per,
    That Microvox talker looks equally as interesting as the Type 'N Talk. It was good that it came as a kit too. I will look at that .bin file.

  6. #6

    Default

    It's all standard parts, and not too complex either. I can send you the entire ROM dump if you are interested. Also, I do have some tips in case you want to try cloning it:

    Use DC-DC converter power modules instead of linear (and resistor/zener) regulators! It draws almost half an amp of 5V, and a 7805 gets quite hot even though it is rated to handle it.

    The Centronics compatible parallel port edge connector did maybe make sense back then, but a micro-ribbon "printer" connector might make more sense today.

    You might want to use a more modern RS-232 driver chip. Maxim makes some drivers with intergrated power converters (like the MAX238 ), and it will save you some space as well. The analog parts still need +12V, but this should eliminate the need for -12V entirely.

    Last but not least: Have some control over where to route power and ground! The original box do have issues with noise, where quite a bit of fuzz from digital signals bleeds into the analog audio-path somewhere along the way. It's probably through return-ground.

    (Small note: the output amp is routed to the unregulated supply, instead of to +12V as the schematics suggest. The LM386 is quite flexible about it, so it's no stress. Another thing, there are jumpers not shown in the schematics to swap TX and RX lines on the RS-232 port.)
    Last edited by per; July 30th, 2018 at 05:57 PM.
    Current systems owned by me:
    Vintage:IBM PC/XT submodel 087 ( 1983 ), [Kon]tiki-100 rev. C (1983), Compaq Portable I ( 1984 ), IBM PC/XT submodel 078 ( 1985 ), IBM PC/XT286 ( ~1986 ), 3x Nintendo Entertainement Systems ( 1987 ).
    Obsolete:Commodore A500 ( ~1990 ), IBM PS/2 model 70/386 type 8570-161 ( 1991 ), Atari Lynx II ( ~1992 ), Generic Intel 486SX PC ( ~1993 ), AT/T Globalyst Pentium w/FDIV bug MB ( 1994 ), Compaq 486DX4 laptop ( ~1995 ).

  7. #7
    Join Date
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    Very interesting thread and article; thanks for sharing. Might just inspire me to look for my Votrax and get it working.

    m

  8. #8

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    Per,
    It would be good if you had time one day to do up an article on that Microvox one with pcb photographs and the .bin like Kevin Horton did for the Type'NTalk. That way others would be able to clone it in the future, like I did for the Type 'N Talk. That Microvox unit looks like it would be amenable to the same type of replication I think. My feeling is that in the future, a lot of these interesting devices are going to disappear, or be near impossible to get, so it worth it trying to document everything as best as possible for history's sake.

    I knew about the MAX238 line driver/receiver, I have used them before, but I stuck to the original Votrax design as closely as possible with the lovely old MC1488, so the clone would be near as exact as possible, in every way. I even tried to get the same vintage IC's ! I'll tell you what has really gone to the dogs though, the modern replacements for the 7805 and 7812 TO-220 regulators. The modern clones of these from the far east have a pathetically thin metal tab that distorts under screw head pressure and gets a smaller surface area contact and therefore poor thermal contact to any heat sink you screw them to. I had to hunt around for vintage NOS Motorola and TI parts ! I wasn't expecting that to happen. Mind you in modern manufacturing voltage regulators have nearly all gone surface mount.

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