Printronix ANSI Printer Graphics

Dot Patterns And Densities

Graphics

The ANSI emulation graphics mode provides both horizontal and vertical do t

placement plotting methods. These methods enable the printing of ASCII

characters in their binary code form. Since each character has a unique

pattern of 1’s and 0’s (dots and voids) that make up its binary code, the

correct placement of these binary forms enables you to form larger images .

For clarity in the text, a binary 1 (a printed dot) will be shown as an X and a

binary 0 (empty dot position) will be shown as a 0.

In the graphics mode, only the low order six bits of a seven-bit character are

used (bits 1-6). Looking at an ASCII code chart, the question mark character

(?) is represented by the binary number 0111111 (bit 7 - bit 1). Since only the

first 6 bits are used, a “?” would print six dots on the paper. A lowercase “j” is

represented by 101010 which would print the following:

Horizontal Graphics / Vertical Graphics

0X0X0X0 LSB

LSB MSBX

X MSB

NOTE: When plotting data, the Least Significant Bit (LSB), Bit 1, is printed

first (left or top bit position) and the Most Significant Bit (MSB), Bit 6,

is printed last (right or bottom bit position).

Notice that in the horizontal graphics mode, the characters are printed on a

single horizontal dot row. In vertical graphics mode, the characters are printe d

six dots high, a character per dot column.

Using a series of question mark (that prints all dots) chara cters in a horizontal

graphic produces a one dot high solid line across the paper. The same

character in vertical graphics mode products a six dot high band across the

paper.

Graphs, charts, and pictures can be produced by repeating, omitting, and

mixing characters across a page.

Table 10 lists the dot patterns for each of the ASCII characters. Each ASCII

character represents six dot positions (or dots) and their spacing is dependent

on the density selected. With a density of 60 and 70 DPI, the dots are spaced

1/60 and 1/70 inch apart respectively. At 120 and 140 CPI, each character

represents six dots spaced 1/120 and 1/140 inch apart. At 180 and 210 DP I

densities, the dots are spaced 1/180 and 1/210 inch apart.

The ASCII characters needed to cover all dot/void combinations are l isted in

the chart below. Other valid character combinations (althoug h repeat patterns

of the characters in the chart) are hex 09-13 and hex 20-3E.