ZXM SOUND BOX

Upgrade Your Sound Capabilities

Let’s have a look through the cupboards at CRASH and see what’s there said the Editor. Lurching towards a tottering pile of assorted hard and software and muttering about simian (but invisible!) fellow operatives, he commenced to hurl review material towards yours truly with all the grace and skill of a seasoned American Football pro. See what you make of that — some of it has been here a bit — ’scuse me, pressing engagement. And with that he swept out. Well this little item has been around for a bit but never let it be said that the CRASH reviewing team turns down material.

The ZXM is an add-on for the Spectrum containing a programmable sound generator which can produce a wide variety of effects. An internal audio amplifier with volume control and loudspeaker gives a very adequate sound level for normal use. The unit fits on to the edge connector, picking up its power from the Spectrum and is compatible with printers and Microdrives, according to Timebase, the manufacturers.

Thoughtfully, an audio socket has been included together with an I/O port to allow other bolt-ons to be added on as well. This is really useful either for amplifying the Beep from the Spectrum by taking a lead from the ear socket on the computer, or for other sound peripherals such as sound samplers. The ZXM comes in the usual anonymous black plastic box with a speaker grille, socket, volume control knob and provision for a joystick control.

Taking a quick look inside reveals the sound chip as the AY-3-8912 — a chip that features in several other micros including the 128K Spectrum. In a nutshell, this device can take your Spectrum’s sound capabilities up to the same level as the 128K machine, giving three channels of sound plus a noise generator, all fully mixable, as well as a wide variety of envelopes (sound shapes). By careful fine tuning all the usual sound effects and tones can be achieved.

Programming the ZXM involves loading values into the 8912’s sound registers. This can be done by writing your own programs or via the editing software provided on cassette with the unit. Some sample sounds — exploding bombs and so on — are included on the cassette. What is lacking in this package is a more sophisticated music program to help you write music directly without having to fiddle about, but the market is littered with programs that drive this particular chip and it should be possible to adapt and rewrite existing software if you were so inclined.

The ZXM instruction booklet is most informative, and gives you all the the internal addresses and I/O port details that are needed before attempting to hook it up to suitable controlling devices via the 7 bit I/O port (don’t get involved unless you’re a dab hand with a soldering iron and are also at one with the internals of musical keyboards).

This box of squeaks brings the 48K Spectrum musically into line with the 128. Both this review and the product are long overdue.

’Scuse me — pressing engagement!