Casio's continuing search for new combinations of size, facilities and price have now resulted in a four-octave mini-keyboard with a versatile memory capable of both teaching and entertaining, which is programmable in a variety of ways.

The visual impact of the MT-70 is immediate; banks of grey and white buttons surround a multi-function l.c.d. display set in the centre of a metallic grey coloured control panel, mounted on an off-white plastic body to give a very modern effect overall. The dimensions, weight, built-in speaker and battery power options make this an eminently portable product, although one of its programming systems is not too suitable for the great outdoors, as we shall see.

The keyboard is split to give the option of one-finger chords, and arpeggio or rhythmic accompaniment, on the bottom one and half octaves, or alternatively the whole keyboard can be made to play one of the twenty 8-note polyphonic voices selected by ten grey switches and a final white 'A/B' selector. There's the usual range of Casio sound's, plus a new 'Synth Bells' setting with an automatic octave repeat on each note, and a pleasantly swelling 'Cosmic Flute'.

However, some of the settings such as 'Funky' are very brief, even with the sustain switch on. There's a vibrato setting with an optional delay, and the voice selected is shown on the l.c.d. display. The rhythms are selected by a five-position slider switch and 'A/B' selector, which seems a slight design inconsistency; however, there's a useful 'fill in' switch which can be tapped at any time to give a rhythm break. The rhythm sounds are of average quality and the accompaniment is a fairly standard arpeggio or a more interesting rhythmic chord effect using one of the 'jazz organ' settings; alternatively it's possible to play one finger chords, with the chord symbol being shown on the l.c.d. display.

The display also shows the status of the memory. This can be programmed 'live' from the keyboard or from sheets of barcodes (as used in supermarkets!) using the light-pen supplied. Each bar enters a line of melody, chord or note length information, so a typical piece may need about 50 barcodes; as it only takes a second to scan a bar this isn't as much effort as it may sound, although it's best done on a flat surface to avoid errors. If there is a mistake in programming, caused by moving the pen too quickly or too slowly or by a mark on the sheet, an audible warning is given.

By erasing the memory (which is normally maintained even while the power is off) it's possible to program in your own compositions or arrangements on the keyboard. Notes are entered one at a time, with the possibility of adding rests, deleting errors and repeating whole sections automatically. The notes are then re-timed against the most suitable rhythm, at a slow speed if necessary, using the 'one-key play' buttons. The whole procedure is repeated for the accompanying chords and the complete composition is ready to play back.

The final major feature is the 'melody guide', which uses a lamp above each key (red for white notes and green for black notes) to indicate which key should be played next in order to produce the required melody; the user can learn his own compositions at whatever speed is convenient, or learn to play the melodies from the large range of bar code music available.

No major problems in design or usage then; the basic sound quality of the instrument and accompaniment voices hasn't changed since the first days of Casio, and although there are a few unusual sounds here, the MT-70 is much more useful (as, I suspect, was intended) as a learning machine/entertainment device than as a performance instrument.

The Casiotone MT-70 is distributed in the UK by Casio Electronics Co. Ltd., (Contact Details)