Saturday, August 20, 2011

Votrax Type 'n Talk


Well, I have decided that I'm going to be building a Votrax Type 'n Talk from scratch. Well, aside from the Votrax SC-01 chip, that is.

I used to play with one of these a long time ago; my dad bought one and I would play with it at an old IBM computer, sending it text and making it say things. They're fun boxes, and they are (relatively) good at reproducing speech. They were made by a company called Votrax, which was a division of Federal Screw Works, in Detroit, MI. There's a lot more on their history on Wikipedia, so if you'd like to learn more about the company and the various products they produced, as well as how their voice synthesis works, check out that article.

The synthesizer is a basic design, uses a simple Motorola 6802 CPU with a 4K ROM and 8192 Bits of memory.
A really awesome guy has taken several Votrax products and de-potted the ROM/CPU, dumped out the ROM and completely traced out the schematic on the board. His website is here: http://www.kevtris.org/Projects/votraxtnt/index.html

Basically, my project is to take the schematic, and build a smaller, more modern version of the Type 'n Talk. Mine will have the same volume/frequency knobs, the same ROM, will operate the same way, with some improvements. Particularly, the updated version I'm building will have a USB port instead of a DB-25 serial, will do away with the baud rate switches (not necessary if I'm handling that internally) and will have a better power supply. Also, it'll have a smaller box, and more speaker outputs.
The difficult part is that the ROM has code in it that takes incoming ASCII text, interprets words into phoneme data, and feeds that into the SC-01 chip. The SC-01 is the actual Votrax chip that generates the speech from phonemes.


SO. I have the schematic, a list of parts, an SC-01, time, and the internet. LETS DO THIS.

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