Competition was thin when the Japanese company Sharp released the MZ-80K in 1979, and for a while the machine was one of the top sellers in the home micro market. Sharp followed it up in 1982 with the MZ-80A, which was seen a being little more than a revamped version of the K.

The design was substantially the same and Sharp had not corrected the shortcomings that were beginning to make it look antiquated. Essentially these were a lack of high-resolution graphics, and the absence of a resident Basic. It has now been largely superseded by cheaper and more sophisticated British micros.

In September Sharp will launch the MZ-700 - its latest bid to re-enter the home computer market. It has been selling well in Japan for the past seven months. Could it be a contender over here?

Sharp will be selling the MZ-700 in two versions - with and without an integrated printer/plotter and cassette drive. In the integrated version, which costs £420, the printer/plotter and cassette unit fit into two compartments behind the keyboard.

It will be possible to buy each separately at a price of £130 for the printer/plotter and £40 for the 1200 baud cassette drive. The standalone machine costs £250.

The appearance and construction of the MZ-700 are highly impressive - they make most British micros look distinctly tacky by comparison. With the printer/plotter and the cassette recorder in place it looks typical of many other high quality Japanese products.

The keyboard has a solid and springy feel. Five function keys are set above it and can be assigned commands from Basic in the same way that the BBC Micro's function keys be defined. The cursor keys are grouped together in a separate keypad and above them are the delete and insert keys which can be used with the shift key to clear the screen or home the cursor.

These and other well-finished details such as a power-on light combine to make the MZ-700 look more like a smark desk-top office machine than a home computer.

At the back of the console are a full array of ports together with an on/off switch and a reset button. As well as a PAL output socket there are sockets for RGB and composite-video monitors.

Read and write sockets enable you to use an ordinary cassette recorder instead of the Sharp's dedicated one, and the printer port likewise allows the MZ-80A printer to be used as an alternative to the printer/plotter.

Also at the back are two joystick ports and an I/O bus. Devices such as a floppy drive or a music synthesiser can be connected to the I/O bus through an optional universal interface board.

The printer uses the same mechanism as the Tandy printer glowingly reviewed in Your Computer March 1983. This runs on any computer with a Centronics or RS-232 interface, and has been snapped up by owners wherever it is available.

It is a remarkably ingenious device which uses four ink pens to write or draw on plain paper in four colours. Vertical strokes are formed by moving the paper up and down against the pen while the pen only moves horizontally. The printer's ROM forms characters by co-ordinating the two movements.

Although the paper is only 4.5in. wide, even at 80 characters per line text printing is very clear - certainly it as a clearer printout than could be achieved by a dot-matrix printer.

So far promising enough. But does the rest of the system match up to its attractive exterior? Sharp describe the MZ-700 as a "clean machine". Clean is a curious and rather inappropriate gloss on the fact that there is no resident Basic in ROM.

As on the MZ-80K and A, the Basic interpreter must be loaded in from tape. Sharp argues that the advantage of this is that you can easily run languages other than Basic.

This advantage does not really count against the nuisance of having to wait three minutes to load Basic. It is not much more difficult to run languages like Forth or Pascal on the Spectrum, for example, although admittedly they cannot occupy the same memory area as the resident Basic.

A far better system is the BBC Micro's, which allows different ROMs to be paged in and out of the same memory space. On the BBC Micro a number of different languages can be resident at the same time and all can be instantly available.

Clean in this context effectively means empty. On power-up the user is presented with 64K RAM and a 4K monitor in ROM. In addition there is 4K video RAM and 4K ROM for the character generator. The monitor which performs such operating-system functions as reading the keyboard and writing to controlling the display, loads in the Basic interpreter to leave 36,567 bytes free for programs.

Colour and graphics are two areas in which the recent batch of micros has overtaken the MZ-80A. The MZ-700 improves the MZ-80A by offering eight colours but the machine's graphics are as poor as its predecessor's. It offers a mere 80-by-50 pixel resolution.

This is not a true high-resolution facility but simply an extension of the normal text display. The code for each character on the screen is stored in the video RAM. Each pixel occupies a quarter of a normal character space and the code for a single pixel - or a configuration of pixels within one character space - is stored in the same way as any other character.

The text display offers 40 columns by 25 lines in upper and lower case. As the screen display takes up only 1K of the video RAM, it acts as a window on a larger display and can be scrolled up and down over the 2K area. The remaining 2K of the video RAM is used to store the colour attributes for screen characters and allows the background and foreground of a single character space to be specified in one of the eight colours.

At a time when you can buy a home computer for less than £100 with 256-by-192 pixel resolution, the MZ-700's lack of high-resolution graphics is a major shortcoming. As part compensation, the machine provides a large set of predefined graphic characters.

Pressing the graphics key switches the keyboard from alphanumeric mode and allows you to print the graphic characters which are shown on the front faces of the keys. There is also an alternative character set which gives a choice of a further 256 characters.

Such a wide selection of predefined graphics certainly gives scope for building up reasonably detailed pictures on the screen, but it is a pity the machine does not also provide for user-defined characters.

This feature, which is now almost standard on British and American micros, can stand in place of a separate high-resolution mode. Anyone who has seen some of the recent games for the Vic-20 will be impressed by the high-resolution graphics which are achieved by manipulating the character definitions.

Most of the features mentioned so far are present on the MZ-80A. Sharp has upgraded the new machine's processor to a Z-80A with a fast clock rate at 3MH but otherwise it seems as if Sharp has done little more than embellish an already outmoded system. This impression is confirmed by a look at MZ-700's Basic.

By and large, the Basic is the MZ-80A's, but substantially extended by a set of printer commands and several other new utilities.

Colour is set by the Color statement followed by four parameters which determine the foreground and background colours of either the whole screen or particular characters. This is rather easier to use than equivalent colour control statements in Sinclair or Commodore Basic.

The commands Set and Reset are the Sharp Basic's only concession to graphics, and respectively plot and unplot pixels.

Renumber and Delete are useful additions to the text-editing commands, as is Merge which joins another program to the existing program file. Other unusual features include the error trapping command On Error, If-Ern and If-Erl. Size gives the number of bytes free and Limit is used to lower the top of the Basic program area.

What one might have hoped for in the way of graphics commands are provided instead for the printer/plotter. Although the Tandy printer can draw lines, axes and circles, it requires a cumbersome string of control codes to do so. With Sharp's printer, the software makes these facilities much more accessible and effectively means you can treat the printer as one would a high-resolution screen.

You can move the pen with or without drawing to any point in the print area as specified by x and y co-ordinates. The x-axis scale extends across the paper from -240 to 240, while the y-axis stretches over 12in. up and down the paper on a scale from 999 to -999. Axis x can be used to draw and mark off the axes and HSet resets the origin.

There are commands to draw lines either relatively to the current pen location or in terms of absolute co-ordinates. By setting parameters you can draw a circle of any radius and arc length from any given centre.

In addition to the graphics plotting mode there are three text modes for printing at 26, 40 or 80 characters to the line. Characters can also be printed upside-down or at right angles to the line. PColor selects the pen colour in both graphic and text modes.

These printer commands redeem the MZ-700 Basic from being fatally dull. To some extent, the facilities they supply serve as an adequate substitute for high-resolution graphics. Indeed the Plot On command enables the screen to be dispensed with by sending all keyboard input directly to the printer. At 12 characters per second, the print speed is fairly slow but fast enough, at least, for two-finger typists.

Otherwise the MZ-700 Basic does not differ greatly from any other Microsoft-derived Basic such as the Dragon's. All the standard string-handling commands and arithmetic functions are there. Print Tab is supplemented by Cursor which places the cursor at any point and Print Using for formatting screen output.

The MZ-700 has a single sound channel that issues an electronic organ-style sound through quite a powerful internal speaker. Volume can be adjusted by a control switch at the back of the computer. The tone, octave and length of notes are entered as string parameters to the Music statement while Tempo sets the tempo.

All in all, Sharp Basic is no better and no worse than most of the other versions of the language at this end of the market. And running a set of stndard test programs on it showed that it was faster than most - faster in fact than any other home computer Basic except for BBC Basic.

Nonetheless, Sharp could have developed the language in a more exciting direction. The inclusion of If-Then-Else, procedures or Repeat-Until would have done a lot to pep up this latest version.

Editing Basic programs is made easy by a full screen editor - the same as that found on Commodore machines. You can move the cursor to modify a line at any part of the screen. A screen editor like this is greatly preferably to the Sinclair or Dragon editors which require you to pull a line down to the bottom before editing it.

One of the advantages of having Basic on cassette is that the entire 64K RAM can be used for machine-code programs. The Basic interpreter includes a machine-code monitor which further encourages machine code programming on the MZ-700.

It includes commands to enter code, examine it, move it, load and save it. You can also instruct it to search for a string and test a subroutine.

Minor but pleasing features like the machine-code monitor go a long way towards making up for the limitations of the MZ-700's design. But one might wonder why Sharp has done so little to develop a new system. The company's own answer is that it wanted to ensure that the MZ-700 was software-compatible with previous models.

A more general explanation might lie in the tendency of Japanese computer manufacturers to stick to conservative designs and to shy away from innovation.

Not everyone, however, wants the most advanced features in a micro. The MZ-700's appeal lies more in the fact that it offers an integrated system. It is highly convenient to have a built-in printer and cassette drive, and the console is a pleasure to use. As the home computer counterpart of a music centre the MZ-700 should find a ready market.

1. The MZ-700 comes into its own as an integrated system. At around £400 for the full system with a four-colour printer/plotter and a cassette drive, a 64K micro with a well-designed console must be considered good value.
2. Graphics and sound on the £250 MZ-700 are crude in comparison with the facilities offered by other micros in this price range.
3. The inconvenience of having to load Basic from tape outweights the flexibility to load other languages.
4. To some extent the inclusion of a printer/plotter with some extensive software to drive it makes up for the absence of a high-resolution screen mode.
5. It may not appeal to games players, but as a reliable and well-built machine, it would be suitable for more serious computing.