Epson MX-70 User Manual - Page 39

Apple, Code Summary

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More Print Control Commands 30 NEXT N 39 PR #0 (Apple) and RUN. OK gang. It's different strokes for different folks. Users who can see their printer merrily printing numbers out to column 75 can give their computer a little pat on the - ah, keyboard. Some TRS-80 users may see the printer tab over to 60, then the carriage returns to print position 0 and continues printing numbers. This is a computer software deficiency - it's not sending the right messages to the printer. Very common. TRS-80's released before Spring 1980 do not send TABS greater than 64. Apple II on the other hand does not tab correctly past column 40. To prove the point, Apple users change line 20 to: 20 PRINT TAB(N); N; and RUN. It turns out that TABS in BASIC are designed for the 40 column Apple screen. TABS past the 40 column limit are treated as strings of blank spaces. There are 50 blank spaces between the 45 and 50. What's this business about an Apple a day? There are several ways around the problem. One is to TAB over with PRINT statements containing blanks between the quotes. A nicer way, (not available on the Apple II) is to use STRING$. See The BASIC Handbook for details. The point of this program was to show that the MX-70 will accept horizontal TABS from BASIC, and help us determine our own computer's capability to send those TABS. Code Summary CHR$ (14) - ENTER DOUBLE WIDTH MODE CHR$ (20) - EXIT DOUBLE WIDTH MODE CHR$ (12) -FORM FEED (USE 140 FOR TRS-80) PR# 1 - ENABLES PRINTER FROM APPLE BASIC PROGRAM PR# 0 - DISABLES PRINTER FROM APPLE BASIC PROGRAM PRINT CHR$ (4) "PR#l" - APPLE DISK ENABLES PRINTER PRINT CHR$ (4) "PR#0" - APPLE DISK DISABLES PRINTER CHR$ (27) "C" CHR$ (##) - ESTABLISHES FORM LENGTH l

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More Print Control Commands
30
NEXT N
39 PR #0
(Apple)
and RUN.
OK gang. It’s different strokes for different folks. Users who can see their
printer merrily printing numbers out to column 75 can give their computer a
little pat on the - ah, keyboard.
Some TRS-80 users may see the printer tab over to 60, then the carriage returns
to print position 0 and continues printing numbers. This is a computer software
deficiency - it’s not sending the right messages to the printer. Very common.
TRS-80’s released before Spring 1980 do not send TAB
S
greater than 64.
Apple II on the other hand does not tab correctly past column 40. To prove the
point, Apple users change line 20 to:
20
PRINT TAB(N); N;
and RUN.
It turns out that TAB
S
in BASIC are designed for the 40 column Apple screen.
TAB
S
past the 40 column limit are treated as strings of blank spaces. There are
50 blank spaces between the 45 and 50. What’s this business about an Apple
a day?
There are several ways around the problem. One is to TAB over with PRINT
statements containing blanks between the quotes. A nicer way, (not available
on the Apple II) is to use STRING$. See The BASIC Handbook for details.
The point of this program was to show that the MX-70 will accept horizontal
TAB
S
from BASIC, and help us determine our own computer’s capability to
send those TAB
S
.
Code Summary
CHR$ (14) - ENTER DOUBLE WIDTH MODE
CHR$ (20) - EXIT DOUBLE WIDTH MODE
CHR$ (12) -FORM FEED (USE 140 FOR TRS-80)
PR# 1 - ENABLES PRINTER FROM APPLE BASIC PROGRAM
PR# 0 - DISABLES PRINTER FROM APPLE BASIC PROGRAM
PRINT CHR$ (4) “PR#l” - APPLE DISK ENABLES PRINTER
PRINT CHR$ (4) “PR#0” - APPLE DISK DISABLES PRINTER
CHR$ (27) “C” CHR$ (##) - ESTABLISHES FORM LENGTH
l <= ## <= 127
29