Installing Superior Software Speech! on the BBC Model B

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Speech! is one of the most impressive software achievements ever released for the BBC Micro.

It generates understandable speech using nothing more than the BBC Model B's standard sound hardware, no dedicated speech synthesiser required. 

In this project, I'll install the Speech! ROM into my BBC Model B, explore how it works, and hear the machine speak for the first time.

Programming the ROM

I found two archived versions of the Speech! ROM:

  • An 8 KB image
  • A 16 KB image
ROM LIBRARY

After comparing both versions, it turned out that they contained the same speech engine. The larger ROM was simply padded to fill a 16 KB ROM image.

Since my Sideways ROM board uses AT28C256 EEPROMs, I programmed the 8 KB ROM into the EEPROM, repeating it across all four 8 KB banks so that it could be selected correctly by the ROM board.

Burning the ROM

Programming was carried out using my TL866II Plus Universal Programmer.

Installing the ROM

Installing the ROM was straightforward. I placed it into the ROM Socket 6 on my sideways ROM board as shown in the red square in the picture below.

Installing the ROM

After programming the EEPROM, I inserted it into a free socket on my Sideways ROM board before refitting the board into the BBC Model B.

Once powered on, I checked that the machine recognised the new ROM.

Typing:

*ROMS

displayed the Speech! ROM in the available ROM list, confirming that the installation had been successful.

*ROM Command

Testing Speech!

Speech! adds several new star commands to the BBC Micro.

The simplest is:

*SAY HELLO

which immediately causes the BBC Model B to speak the supplied text through its internal speaker.

The ROM also supports changing the voice pitch using:

*PITCH M

followed by another *SAY command.

Different letters produce different voice pitches, allowing the speech to sound deeper or higher.

For users wanting even greater control, Speech! also includes a *SPEAK command that allows speech to be generated directly from phoneme data instead of normal English text.

Speech Commands

How Does It Work?

One of the most fascinating aspects of Speech! is how it produces speech without any dedicated hardware.

Instead of storing every possible word, the software stores a collection of 49 phonemes, the basic sounds used to construct spoken English.

When you enter a sentence using the *SAY command, the ROM:

  1. Converts the English text into phonemes.
  2. Applies pronunciation rules.
  3. Plays each phoneme through the BBC's sound chip.
  4. Smoothly blends neighbouring sounds together to improve clarity.

This allows the ROM to produce an effectively unlimited vocabulary while fitting into just 8 KB of ROM.

It's a remarkable piece of optimisation and one of the best examples of what skilled programmers achieved on 8-bit computers.

Final Thoughts

Speech! is one of those upgrades that perfectly demonstrates the ingenuity of the BBC Micro community.

Although the speech isn't as natural as modern text-to-speech systems, it's incredibly impressive considering it was released in 1985 and runs on a 2 MHz 6502 processor.

It's also a great reminder that many of the most innovative BBC Micro projects weren't hardware expansions at all, they were examples of programmers pushing the machine far beyond what most people thought was possible.

This ROM has earned a permanent place in my BBC Model B.

Watch the Video

If you'd like to see the installation process and hear Speech! in action, check out the accompanying YouTube video where I program the ROM, install it into my Sideways ROM board, and test the speech commands on real hardware.

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