IBM 4400 manual Plotting a Bit Image Pattern, 128

Plotting a Bit Image Pattern

ASCII

CHARACTER

DECIMAL

VALUE

BINARY	VERTICALLY
CODE	TO ROTATED DATA
EQUIVALENT	BYTE

BIT IMAGE PATTERN

		128	MSB
		64
		32
A	= 65	16	=
		=
		8

4

2

1

Figure 28. Vertical Data Byte Pattern

The byte in the previous example (or any other byte) can be identified by its binary, octal, hexadecimal, or decimal equivalent and subsequently can be used to generate a Bit Image pattern. A table of the standard ASCII character set and equivalences is included in Appendix A. Use this table to quickly identify the various equivalences of ASCII characters. Bit Image plotting is not limited to printable ASCII characters; bit image patterns can be plotted for any 8-bit data byte with decimal values ranging from 0 through 255.

Plotting a Bit Image Pattern

A Bit Image pattern can be developed as follows:

1.Lay out the graphic to be printed on a quadrille pad or graph paper.

2.Determine the decimal equivalence of each bit image data byte required to produce the pattern.

3.Write a program to generate the complete pattern.

4.Enter and run the program on the host computer.

Figure 29 illustrates steps 1 and 2. Eight vertical cells are used to create the Bit Image pattern corresponding to the eight bits of the vertically rotated data byte. Dots are placed in the cells to provide a visual representation of the graphic to be printed. Each dot corresponds to a 1 or true bit in the data byte. In this example, seven Bit Image data bytes are required to create the dot pattern. These seven data bytes must be specified in the written program (step 3) to generate the entire pattern.

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