Commodore PET User Manual page 394

Program 10, ALL THE WAY.
5 REM PROGRAM 10 ALL THE WAY
10 REM
*******
B LAN K E T
*******
20 REM CONTINUOUS-LINE DISPLAY OF ONE
30 REM CHARACTER ENTERED FROM THE
40 REM KEYBOARD
50 REM
***********.*****.*******.*****
913 PRINT"HIT A KEY OR <R:> TO END";
100 GET C$:IF (:$="" GOTO 100
105 IF C$=CHR$(13) GOTO 1713
lia PR 1
~..jT":']"
; . : REM CLEAR SCREEN
120 FOR 1=1 TO 999 :REM 999/40=25 LINES
1313 PRINT C$;
1413
NE:'~T
150 POKE 33767,(ASC(C$)AND128)/2 OR (ASC«(:$)AND63)
160 GOTO 100
170 END
Changes
Add:
Change:
Delete:
Comments
Line 5
Lines 120, 150, 160
None
Following the hint given with the problem in Chapter 3, we can get the
character to print in 999 positions simply by changing the value of the FOR . . .
NEXT ending index in line 120 from the value 920 to the value 999. However. the
program cannot PRINT into the 1000th screen position without scrolling the dis-
play up one line. Recall that the previous program. PRINTOVER Il. had to stop short
of printing in the final position to avoid scrolling - but that program just wanted
to blank the position. and it was found that the position would always be blank
anyway.* The current program needs to display a character at that position. The
only way to accomplish this with the PET is to POKE the character's screen value
into address 33767. which corresponds to the last screen position. POKE does not
use the cursor and th us does not produce scrolling.
'The final position will be blank unless vou POKEd a character there before running the program. If
vou wanted to be absolutelv sure about blanking this last position, vou could do so bV POKEing a
blank to it with a POKE 33767.32
381