Epson FX-80 User Manual page 192

Line 20 stores the graphics entry string into G$. This string produces
Low-Speed Double-Density graphics of 819 columns (51
+
3 x 256
=
819). Line 170 fires the bottom graphics pin 819 times. The X loop
repeats the routine to print the line 3 times.
Because this line-printing routine (lines 160 to 180) will be used
again to print the bottom three lines of the figure, it is set aside as a
subroutine. It is called by the GOSUB in line 20 and separated from
the rest of the program by the STOP in line 150.
So far, so good! Now for the rest of the figure. The following lines
control the 4-step process:
8~
FOR X=l TO L: LPRINT CHR$(l);: NEXT X
l~~
LPRINT CHR$(1)CHR$(2)CHR$(4)CHR$(8)
CHR$(16)CHR$(32)CHR$(64);
ll~ FOR X=l TO H: LPRINT CHR$(64);: NEXT X
12~ LPRINT CHR$(64)CHR$(32)CHR$(16)
CHR$(8)CHR$(4)CHR$(2)CHR$(1);
The 7-dot rise and fall are printed by lines 100 and 120. The lengths of
the low and high sections are stored in DATA statements, then read
into the variables Land H. Line 80 prints the bottom pin L times; line
110 prints the top pin H times.
, The next step is to add the READ portion of the program:
5~
READ L,H
6~ L=L*7: H=H*7
7~ IF L=~ THEN 9~
9~
IF
H(~
THEN LPRINT: GOT
a
15~
13~
GOTO
5~
Line 50 READs numbers from the DATA statements in pairs: the first
is stored into L, the second into H. Land H are then each multiplied by
seven; this extends the width of the figure without increasing the size
of the DATA numbers. This enlargement factor must be the same as
the number of dots in the rise and fall, or else the design will not line
up properly.
If L is READ as 0, line 70 skips line 80. This enables us to print the
center portion of the X, where no low section is required.
Line 90 serves two purposes. It forces a line feed each time a nega-
tive number is read, and it skips the last three steps of the 4-step cycle
so that each print line can end on a low.
161