Program
6,
SPEED UP.
5
REM
PROGRAM
6 SPEErl
L1P
10
REM
*******
B
LAN
K E T
~**~***
20
REM
C:ONT
1
NLiOLlS-L
1
NE
Il1
SPLA'T'
OF
Ot'~E
30
REM
CHARACTER
ENTERED
FROM
THE
40
REM
KEYBOARII
50
REM
***.*
••••••••••*
•••••••••••••••
90
PRItH"HIT
A
KE'r'
OR
<l'::>
TO
END".;
100
GET
C:$:
IF
C$=""
GOTO
100
105
IF
C$=CHR$(13)
GOTO
170
1
€:16
FOF~
1=1T07
107
C$=C$+C$
108
NEXT
:REM
C$=128
C$/S
109
C$=C$+LEFT$(C$,
1(2)
:REM
C$=230
C$/S
110
PF:
1
NT
"::1"
.;
: RHl
CLEAR
SCREEN
120
FOR
1=1T04
:REM
230.4=23
LINES
1:30
PRltH
C$';
140
t'iE~<:T
1
5€:1
PI':
1
NT"
PHEloJ
! "
16~::1
GOTO
90
17€1
am
Changes
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Comments
Lines
5,
106-109
Line 120
None
Here vou have to realize that one long string prints more quickly than a num-
ber
of
shorter strings. Ideally we would print one 920-character string. However,
on
the
PET,
strings are Iimited to a maximum
of
255 characters. The program
breaks the 920 positions into four 230-character quadrants.
At
lines 106 to 109 it
concatenates the keyed-in character into a 230-character string.
which
is
a
quarter of the screen
area
to
be
covered by the display character. The FOR. . .
NEXT loop at lines 106 to 108 uses a pyramided concatenation to quickly
"grow"
the string to 128 characters. Then at line 109 the 128-character string
is
concate-
nated to the leftmost 102 characters
of
the string to give a 230-character string of
the display character. The
FOR
...
NEXT print loop at lines 120 to 140 needs to
print this longer string only four times
to
fill the screen.
375
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