Epson FX-100 User Manual download pdf (Page 221)

mined by the data numbers as columns 0 to 10, then in Proportional

Mode the minimum and maximum starting and stopping columns will

be 0 and 11. Why

instead of 10? Column 11 is the maximum value

because Proportional characters are always Emphasized; this makes

each character wider by one intermediate column. So when defining

your own characters for proportional printing, always reserve one

extra column.

Suppose you want a character to start in column 1 and end in col-

umn 10. How do you put this information into the attribute byte? The

starting column number (1) is converted to a 3-bit binary number

(001) and stored in bits

4, 5,

and

of the attribute byte. The ending

column number (10) is converted to a 4-bit binary number (1010) and

stored in bits 0 to 3. The conversions are shown in Figure

15-5.

Figure

15-5.

Attribute byte conversions

The full 8-bit attribute byte, then, is composed of three parts:

1. Bit

determines which pins are used to print the character.

2. Bits

4, 5,

and 6 determine the starting column number.

Bits 0, 1,

and 3 determine the ending column number.

So the attribute byte constructed in Figure 15-5—CHR$(154)—uses

the top eight pins, starts printing in column 1, and ends in column 10.

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Epson FX-100 User Manual Page 221