Epson LX-90 User Manual - Apple IIc 8699 PIC for LX-90 - Page 54

Screen Dump Program, authors, W.H. Darnall and D.B. Corner.

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In this program the number 128 in the DATA statements signals the end of a print line. This is the reason for the IF-THEN statement in line 140 that skips to line 190 and causes a line feed. The other special technique used in this program is found in lines 150 and 160. Since some of the data numbers are repeated many times, using negative DATA numbers for repetitions saves typing. Line 150 tests for a negative number, and if it finds one, reads the next two numbers and prints their pin patterns the number of times indicated by the negative number. For example, when the minus 6 in line 800 is read, the program then reads the next two numbers (8 and 0) and sends them to the printer 6 times. This feature is not a necessary part of the program, but it does allow you to type fewer data numbers. Otherwise the program is a straightforward graphics program that uses 7-dot line spacing and reads numbers from DATA statements and sends them to the printer using the POKE subroutine. If you want to see the figure in other densities, change the "Y" in line 130 to "L" or "Z". Screen Dump Program Some software programs perform what is called a screen dump in which whatever is on the computer screen is sent to, and printed by, the printer. With this feature you can print any graphics that you create on the screen. A screen dump program written in Applesoft BASIC is included below so that you can see a screen dump in action and can print your own graphics that you create on the screen. This program is reprinted from The Epson Connection: Apple through the kind permission of its authors, W.H. Darnall and D.B. Corner. 52

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In this program the number 128 in the DATA statements signals the
end of a print line. This is the reason for the IF-THEN statement in line
140 that skips to line 190 and causes a line feed.
The other special technique used in this program is found in lines
150 and 160. Since some of the data numbers are repeated many
times, using negative DATA numbers for repetitions saves typing.
Line 150 tests for a negative number, and if it finds one, reads the next
two numbers and prints their pin patterns the number of times indi-
cated by the negative number.
For example, when the minus 6 in line 800 is read, the program then
reads the next two numbers (8 and 0) and sends them to the printer 6
times. This feature is not a necessary part of the program, but it does
allow you to type fewer data numbers.
Otherwise the program is a straightforward graphics program that
uses 7-dot line spacing and reads numbers from DATA statements and
sends them to the printer using the POKE subroutine. If you want to
see the figure in other densities, change the “Y” in line 130 to “L” or
“Z”.
Screen Dump Program
Some software programs perform what is called a
screen
dump
in
which whatever is on the computer screen is sent to, and printed by,
the printer. With this feature you can print any graphics that you
create on the screen.
A screen dump program written in Applesoft BASIC is included
below so that you can see a screen dump in action and
can
print your
own graphics that you create on the screen. This program is reprinted
from
The
Epson
Connection: Apple
through the kind permission of its
authors, W.H. Darnall and D.B. Corner.
52