VIC-20 Talk-Back speech synthesizer

This is the VIC-20 Talk-Back, a speech synthesis electronics kit sold by Maplin way back in 1983. The Maplin part number is GB17T LK00A. The board was designed by Mark Brighton.  This was a home build kit that you could build to make your VIC-20 talk. The speech system had a GI SP0256-AL speech chip at its core. This chip provided some of the following features :

  • A programmable digital filter which simulates the human voice tract.
  • A 16K ROM which contains the data for the 64 allophones.
  • A micro controller which controls the flow of speech data to the filter and the linking of allophones to produce words. A pulse width modulator.

There was no ROM on the PCB. You made it talk by POKEing it some code. So, this device did not take up any RAM – so you still have your 3k or more RAM free!

Maplin GB17T Talk-Back circuit diagram.
 Maplin GB17T Talk-Back circuit diagram
Maplin GB17T Talk-Back board layout
Maplin GB17T Talk-Back board layout

There was a small demo piece of code that you tested the speech synthesizer with. Here is a copy of the code from the manual.

Sample code for the Maplin speech synthesizer
Maplin GB17T Speech Synthesizer – Demo Program

To save you some time, I have typed in the program into my VIC-20, tested it and saved it as a .PRG file. I have also put the file into a D64 disk image. There are several ways you can copy these files to a real VIC-20. A SD2IEC is a great device – and there are many more such systems out there.

Maplin GB17T Speech Synthesizer (Talk-Back) demo PRG

You can also download the complete article from the March 1983 edition of the Maplin Magazine. The magazine includes all information you need to make the Talk-Back say anything you want. If you write any applications using the VIC-20 Talk-Back, be sure to let me know and I will put a copy of your code on this site.

Maplin Magazine – March 1983 – VIC-20 Talkback PDF

4 thoughts on “VIC-20 Talk-Back speech synthesizer

  1. Hi, I wrote the article and designed this project whilst working at Maplin all those years ago. It is rather pleasing to see that there is still some version of this available online, although the number of current VIC-20 owners must be rather small and the chances of getting an SP0256 chip seem even smaller!

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