Notes on Concepts and Facilties

The HP DeskJet is a pleasingly silent printer which offers an excellent 300 dpi print quality at a very attractive price. We consider it as a low cost laser printer alternative for everybody's everyday use. The greatest disadvantage is that by default the printer comes without a single byte of RAM for downloading fonts. Even upgrading it with the maximum of two RAM cartridges will supply no more than 256 KB of font storage. For many documents this amount is far away from being sufficient. Therefore most of the print job has to be done in grafic mode. Unfortunately this brings two unpleasent aspects into account. First the driver has to manage a rather great bitmap (over 1 MB for a default DIN A4 page) and second printing in high resolution grafic mode is a very dull affair.

Both problems can be solved by reducing the resolution to 150 or even 100 dpi. RUMdjet offers this possibility as an option. For high quality output, however, the 300 dpi resolution is indispensable. This demands a careful handling of storage. The usual approach of swapping the bitmap to disk led to an unacceptable increase of processing time. Better results we obtained by deviding the page from top to bottom into several pieces which were processed and printed independently. The multiple reading of the dvi file can be almost neglected.

Some other points concerning the driver software should be mentioned:

• RUMdjet does not need any swap space on disk. For us this point is rather important. All of the university PCs are connected to a campus network. Via the network, software including TEX can be loaded, but there is no disk capacity to store private data. So all the micro computers which are equiped just with a floppy disk drive can run TEX and RUMdjet, but cannot store a great bitmap.

• The output can be directed to a printer immediately. This helps to avoid the creation of big printer output files. RUMdjet is able to compute the next output part while the DeskJet is processing its internal print buffer. So the printer is busy without any interruption.

• An arbitrary number of arbitrary large fonts can be used in a document. If the RAM-storage is not sufficient to hold a character image, the image is ored line by line into the current bitmap immediately. The above mentioned toolkit contains a set of programs to insert pictures created by normal PC software into a TEX document. This is achieved by making a special font with possibly very large characters of every picture. RUMdjet can handle those fonts independent of their sizes.

• The output can be sent to a HP LaserJet of an arbitrary version as well.

• For a quick look at the printed document the resolution can be reduced to 150 or 100 dpi. This leads to a noticeable decrease of printing time and printfile size.