Commodore PET User Manual page 391

Program 9, PRINTOVER Il.
LINES
:REM TO
:REM PAUSE
5 REM PROGRAM 9 PRINTOVER II
10 REM
*******
B LAN K E T
*******
20 RE1' 1 COt-n l NUOUS-L l NE DI SPLA'T' OF ONE
30 REM CHARACTER ENTERED FROM THE
40
REM KEYBOARD
50 REM
***************~**~~~**~~
........**
E:5
0$="
86 R$=" "+Q$ 'REM 40 BLANKS
87 S$=R$+O$ :REM BLANKS FOR 2 LA8T LINES
90
F'RINT"HIT A
tŒ',-'
OR -CR> TO Et·m".:
1(10 GET C$: IF C$="" GOTO 100
105 IF C$=CHR$(13) GOTO 170
107 IF F-C>0 THEN GOSUB 600 :REM TO BLANK 2
110 PR
l
NT"
l:lI" ; :
REM HOt'lE CURSOR
120 FOR 1=1 TO 919 REM 919/40=23 LINES
1:30 PRINT C$.:
135 PRIt-lT
"~".:
cs;
"!!II".; :
REM
PF~INT
REV
140 NEXT
141 PRIt-lT
cs;
142 GOSUB 610 :REM TO BLANK 2 LINES
150 PRINT"PHEW!"
155 FOR 1=1 TO 1000:NEXT
157 F=l
160 GOTO 90
170 END
6(10 PR
II'4T"
j l I J '
[Q[Q[Q[Q[Q[Qrml[Q[Q[Q[Q~"
;
610 PRINT S$;
":T1II".;
62(1 RETURN
" : RE,..l 39 BLANKS
NEXT-TO-LAST
LI
NE
Changes
Add:
Change:
Delete:
Lines 5. 85-87. 107, 135. 141-142. 155, 157. 600-620
Lines 110, 120
None
Comments
The extensive changes made here illustrate the lengths vou have to go to in
order to smooth the rough edges of a simple program modification. (Recall that in
PRINTOVER
1
vou had to change just one character of the program to get the
tvpeover effectll
To show movement at the printing of each character. the character is
printed (Iine 130) and then in the next position the reverse of the character is
printed (Iine 135). At line 135 the cursor is also backed up one so that the next
loop iteration will print the character in the same position where the reverse
character was just printed. The end loop index in line 120 is changed from 920 to
919 so that the reverse character. which runs one ahead of C$. will not print
bevond the 920th position. Line 141 has to be added to print C$ at this last
character displav position.
378