The ViewPlot program is part of Acornsoft's View family, and allows various graphs and charts to be produced from data contained in a ViewSheet spreadsheet (or a ViewStore data file). It also allows charts to be constructed from data which is directly entered into the program.

The disc-based program is menu-driven with three main sections controlling data entry, chart presentation from a single set of data, and the production of graphs combining several sets of data. Direct data entry is quite straightforward and allows for up to 100 pairs of data values, which must then be saved to a disc file. A chart of the data can then be prepared by choosing the next menu option and following the prompts given. A choice of line graph, bar chart or pie chart is offered, although moving from one form of presentation to another requires all the menu prompts and the data file to be re-entered - an irritating feature once serious work has begun.

Once a graph is displayed, the colours of the backgound, axes and lines can be altered by using the function keys, and the most pleasing form of presentation quickly obtained. Unfortunately, although modes 0, 1, 2, 4 and 5 can be used on the B+ and Master (and if a 6502 second processor is used), only modes 4 and 5 are available on a standard BBC B, presumably due to the program space required. Further, if the mode is changed or the type of chart required is altered, time-consuming disc accesses are needed as parts of the program re-load and the data is re-accessed.

Data can be combined in various ways. Firstly, either one, two or four graphs and charts can be displayed on the screen at the same time by splitting the screen into windows. This allows, for example, the same data to be viewed in the three alternative modes of presentation, or for four different series of data to be seen together (see illustration), although this must be done in mode 4 on the model B.

Secondly, graphs of the same type (or different types, although this is not recommended!) can be overlaid on one another. In this case, the vertical axis is rescaled so that it includes the maximum range in all of the data sets, and provision for a new title is made. Unfortunately, the horizontal axis overwrites itself if different legends have been used on the original graphs. This facility is best used with line graphs, as bar charts rapidly become illegible when more than two or three are combined. The process is completely automatic with the user having no control over, for example, the spacing and widths of the bars. But again, the colours used in the display can be adjusted, and the patterns used to fill bars and pie segments selected (see illustration).

Once a screen display has been constructed and adjusted to give the most pleasing presentation, it may be saved to disc. Here one of the poorer aspects of the package becomes apparent. The screen dump automatically saves to the program disc in drive @ under the name Image. The file thus has to be *COPY(ed) to another disc and renamed if several dumps are required. Similarly, data is saved on the program disc unless the rather tedious filename notation is used. The manual makes no mention of this latter possibility and is otherwise rather thin on details of importance to the serious user. One would really expect a program of this sort to ask whether separate data and program discs were being used, and on which drives.

A printer dump is also supplied that allows a screen to be sent to the printer. Only one size of dump is allowed (approx 9" x 6", fitting neatly onto A4 paper) and the dump is for Epson FX or compatible printers. It worked adequately on my MX80, but took over 8 minutes to dump a single screen.

However, the main reason for the program's existence is to extract data from ViewSheet spreadsheets and to plot graphs from it. This can be done in two ways. The first involves spooling part of the spreadsheet using the *prepare program supplied. This works easily enough, provided the data required is in two adjacent columns (not rows!), and a data file suitable for ViewPlot is the result. The second method involves the creation of a link file. The advantage of the link file is that it is permanently associated with the appropriate spreadsheet, so that whenever a change is made to the spreadsheet, the link file is automatically updated. In this way you can move quickly between the spreadsheet and the graphical plots. The disadvantage is that the manual is very cryptic as to how such files should be created, and will probably be quite incomprehensible to most users. I am familiar with the BBC micro and the ViewSheet spreadsheet, but it took me several hours of trial and error to get a working 1link file. It is quite inexcusable for such a vital feature to be so badly explained, and it will make the whole program useless to many purchasers.

The best feature of the program lies in its ability to construct a 'slide' show of linked screens of graphs that can be presented in sequence. The screen output is so much better than the printed output and, in any case, there seems to be no simple way of incorporating graphs into reports produced using View. The slide facility allows a whole series of graphs, either singly, or in twos or fours, to be presented in selected colours. The number in a sequence is limited only by the catalogue capacity, as one file is linked to call the next file. The screen display is quite quickly written, and the whole effect is impressively professional.

The program has to be compared with Inter-Chart from Computer Concepts (see review in Beebug Vol. 4 No. 8). ViewPlot suffers from being disc-based rather than ROM-based. It has less memory available for screen and data on a model B and is considerably less user-friendly. It's far easier to produce charts from Inter-Sheet using Inter-Chart than from ViewSheet using ViewPlot, and I cannot recommend the latter combination to new buyers. But if you already have ViewSheet or require its unique features (especially the screen windows) ViewPlot is the only way to get graphical output and, once set up, works passably well. Its strongest feature is its ability to produce a 'slide' show, and if you wish to present data in this form, it is well worth the price. But it is badly let down by its manual on the vital matter of constructing the necessary link files.