Column reservation numbers

The graphics command requires more than one number to specify how many columns to reserve because one line can use thousands of columns, but the LQ does not use numbers larger than 255 (decimal). Therefore, the graphics mode command uses two numbers for reserving columns.

To figure the number of columns reserved, multiply the second number by 256 and add it to the first number. Since the command is set up for two numbers, you must supply two even if you need only one. When you need fewer than 256 columns, just make n1 the number of columns you are reserving and make n2 a zero.

For example, if you wish to send 1632 columns of graphics data, n1 should be 96 and n2 should be 6 because 1632 = 96 + (6 x 256).

The LQ will interpret the number of bytes determined by n1 and n2 as graphics data, no matter what codes they are. This means that you must be sure to supply enough bytes of graphics data or the LQ will stop and wait for more data and will seem to be locked. If, on the other hand, you supply too much graphics data, the excess will be interpreted and printed as regular text.

First graphics program

This first program is just a simple example to show you how the graphics command, column reservation numbers, and data can be used in a BASIC program. Type in and run the following program; be especially careful to include both semicolons. The program produces the printout you see below it.

20 LPRINT CHR$(27)"*"CHR$(32)CHR$(40)CHR$(0); 30 FOR X=1 TO 120

40 LPRINT CHR$(170);

50 NEXT X

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