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Full title Utilities Tape - printline
Year of release 1985
Publisher Boldfield Computing
Producer / Author(s) Charles Wehner
Memory 3k
Type AceForth Word
Original Cost £9.89
Instructions Click to download

This routine is one of five words saved on the cassette and further words included in the main programs ZX-PRINTER and WORDACE, which are intended for the advanced user. These enable a wide range of printing options to be generated and customised for your own specific purposes.

However, before these are used, some explanation is required of the principles involved. Usually, the most condensed form of creating information (such as graphics characters) is by means of an algorithm which works like a mathematical formula.

However, complicated and virtually random characters (such as the alphabet) are not readily described in this way, and they have to be stored explicitly in a data array or 'look-up-table'. The words provided here encompass both techniques. When the second method is used, you will see an associated dot addressable array, normally called DOTFILE present (eg. THINPRINT, WORDACE etc.).

You will also see that some operations are performed by supporting words which can be used separately if required. For example, the ITALIC Font uses SLOPE, and the sideways printing in WORDACE uses TURNDOTS.

Whilst most of the words are useful in their own right, the real intention is to illustrate the methods adopted and hence to allow the experienced user to write his own programs based on the same routines.

The first word in this category is PRINTLINE (load printline).

This primitive expects the address of a 256 byte buffer on the stack. As an example it is supplied with a DOTFILE containing the line 'This is Jupiter ACE printing' . To see this actually printed enter: DOTFILE PRINTLINE (in this case the DOTFILE was previously created by:

CREATE DOTFILE 256 ALLOT and filled with the sample pattern.

The bytes in the DOTFILE are in scanning order). You can also check how PRINTLINE works within the ZXPRINTER suite for outputting each line of special characters.

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