Here we can see more clearly the two speech chips and the 1770 disc interface.

The Acorn speech upgrade is quite rare and I was lucky to get one. Essentially it is two 28-pin ICs, both made by Texas Instruments, namely the TMS5200 speech processor and the TMS6100 speech data chip.

The full upgrade also has parts to add a ROM cartridge connector to the keyboard. For this, you need to add a couple of capacitors to the keyboard, add the ROM socket and add a 10-way set of pins next to the ribbon cable connector and you then take a 10-way ribbon cable from the pins to the connector on the BBC motherboard just in front of IC98.

The idea behind this was to allow extra ROMs of speech data to be plugged into the keyboard ROM socket to expand the range of the speech system. As far as I know, nothing ever came of this. The speech upgrade I bought came with a keyboard with the ROM cartridge socket installed but I am not using it at the moment.

The speech system works perfectly well with the two chips installed. It does not need any extra software when the two ICs are present. Speech is generated either using the SOUND command or a call to OSBYTE &9E and &9F to read or write to the speech processor.

The easiest way to use speech is by the SOUND command which takes the form:

SOUND -1,(number),0,0

where -1 refers to the number of the Phrase ROM, ie. 1, and (number) is the number of the word or word-part to be spoken. In practice, the ROM number will always be -1 as only one Phrase ROM, called PHROM A and containing Kenneth Kendall's voice, was ever issued.

Using the OSBYTE call allows you to read or write directly to the speech processor. This way, you can generate your own speech but this requires vast amounts of data to be sent to the speech processor to create each individual sound, with the added complication that only one byte at a time can be sent and the bytes must be sent in reverse order.

Next to the speech chips is the little Watford 1770 module which replaces the 8271 floppy disc controller. To upgrade from 8271 to 1770 DFS, you need to take out your old 8271, keep it for when your favourite games don't work because of the disc protection they use, or sell it for a fortune on E-Bay, plug in a suitable 1770 module, remove IC86 and link pins 1 and 4 together with a link. In the picture, you can see that I have done this with the loop of a paper clip which does the trick very nicely. Then plug in a 1770 DFS ROM and consider your Beeb upgraded!