---

Printer drivers

Only one printer driver at a time may be present. If you load a second printer driver, you will find the first one is automatically deleted.

If you are offered a choice of print resolutions, you must make a trade-off between quality and convenience. Higher resolutions give better print quality, but the printing will take longer. Even 9-pin dot-matrix printers such as the Epson FX-80 and its clones when operating at their highest possible resolution (240 x 216 dots per inch) can deliver quite attractive print, but allow at least 15 minutes to print a full A4 document (portrait). This is because three passes of the print head (with the paper advanced 1/216 inch between passes) are needed to achieve the vertical resolution of 216 dots per inch. You must allow far longer for the printing of landscape pages since these are printed sideways and the graphics data assume portrait orientation; all the bits (representing printed dots or spaces) must be differently assembled into bytes for sending to the printer.

If you regularly use the same choices on your printer driver, you can save time by saving your preferences using the Save option on the printer driver menu. When you have done this the driver will start up with your preferences selected.

Use of remote printers

There are limitations, however, since a busy page of A4 at 300 dots per inch will produce a file nearly 1 Mbyte in length, and an Archimedes disc has a maximum capacity of 800 Kbytes. You may wish to transfer files to MS-DOS format for printing on other systems, but remember that the maximum capacity of an MS-DOS disc handled by a RISC OS machine is 720 Kbytes.

To spool output from the printer driver to a file click Menu over the icon on the icon bar, then move to the right of the option File. This will open a writable icon in which you can specify the filename. You will have to specify the full pathname of the file if you do not want it written in the current directory.

If the destination machine is an Archimedes or A3000, printing is simple. From the RISC OS desktop drag the file icon on to the printer driver icon. If the destination machine is an MS-DOS machine the MS-DOS command :

PRINT <filename>

is sufficient. The printing takes place in the background, freeing the computer for other tasks. If the destination machine is a BBC Micro it is most convenient to use a simple BASIC program to send the bytes to the printer without affecting the VDU drivers, the following works well:

    10 REM PRINT PRINTER FILES
    20 CLS:INPUT"Enter filename"' F$
    30 channel=OPENIN F$
    40 IFchannel=0 PRINT"File not found":END
    50 VDU2
    60 REPEAT
    70 VDU1,BGET#channel
    80 UNTIL EOF#channel
    90 CLOSE#0
   100 VDU3
 

Speed of printing

Since an A4 page at 300 dots per inch would take nearly 1 Mbyte, clearly a 1 Mbyte machine cannot hold a printer image of the whole page. So the printer driver uses whatever memory is available and divides the page into sections that will fit in the available memory. For each section every object on the page must be examined and, if its boundary overlaps that of the section being printed, it must be plotted on the virtual screen. It is this repeated plotting that takes the time. Clearly the greater the memory that can be made available to the printer driver, the fewer the sections will be needed and the faster the page will be printed.

You can make extra memory available in the following way. Having selected your required printer resolution, delete the printer driver icon from the icon bar. This will clear a valuable 64 Kbytes of memory for the printer. The module which actually drives the printer will remain in memory. Secondly, change to screen Mode 0. To do this you will need to use the last writable item in the Mode menu on the palette icon. Although the screen display will look crude, the print quality will not be affected. Changing to Mode 0 from Mode 12 will save you another 56 Kbytes. You should find that these actions appreciably accelerate printing.

Paper sizes

If, however, you use a dot matrix printer that handles continuous or fanfold stationery, you may find yourself in serious difficulties. The problem is that Ovation will always assume that your printer is handling A4 paper. In practice it is handling a form length of either 11 or 12 inches, neither corresponding to A4, so that on a multi-page document soon the printed pages are straddling the perforations in the stationery.

The solution is to load the file called PrData in the !PrinterDM directory into the Edit application and to edit it slightly. This file contains the essential data about the various printer types which the driver handles. Near the beginning of the file is a line which reads:

    job_prologue:   ""
 

    job_prologue:   "<27>C<70>"
 

Print margins

If you find that there is matter on the page which is just outside the printable area, you may be able to redesign your page so that it fits wholly inside the printable area. Alternatively, if there is space at the other end (or side) of the page, you can move the printable area using the Printer Setup dialogue box from the File menu. Positive adjustments of the Y axis shift the printer margins downwards; negative adjustments shift them upwards. Positive adjustments of the X axis shift the margins to the right and negative ones to the left. A further alternative is to rescale the printer image, again from the Printer Setup dialogue box.

One problem with dot matrix printers is that they are not capable of printing in the bottom 20 mm of the page. The printer margins, of course, allow for this, and you will soon become accustomed to designing your pages so that they fit in the printable area. If, however, you opt for an A4 landscape document, you must separately select landscape on the printer driver. The printer will now print sideways, the right-hand edge of your document being printed first and the left-hand edge last. But the left-hand edge could well now be inside the foreshortened bottom edge of the printer margin. Do check on this and ensure that all of your document will be printed.

Deskjet Plus printer driver margins

• Top    =    2.0mm
• Bottom    =    10.0mm
• Left    =    3.0mm
• Right    =    4.2mm