get
carried away
with this program, you will want to calibrate it with a precision-type
timepiece
(increasing or decreasing the
"500"
figure as needed). Over the short run, this is
quite
a
good timer. Note that we are not triggering this with the
60
Hz line frequency,
but
relying
solely
on
the amount
of
time
required
to execute FOR-NEXT loops.
Oh, Yes . . . The
PRINT
AT
. . .
Anyway
—
let's not
lose sight
of the forest for the trees (or something equally
trite). The
purpose
of
this
little program
is to demonstrate the PRINT
AT
statement.
We used it twice.
By
carefully
squinting at the layout chart you can find address
#407,
with
#470 right
below
it. With
blazing
speed,
the HMS (no, no, not Her
Majesty's
Service
—
it stands for
Hours,
Minutes
and Seconds), are printed
—
and the HM&S
updated each second.
For
the
real
clock nut, see
Part
C for
an operational clock
program. It only
needs your
closer calibration to
be an
acceptable sundial.
Most expensive clock in the
house!
That's
How the Ball Bounces
Meanwhile,
back
with the
bouncing ball. Let's reload the program from the first graphics
chapter. It reads:
10
CLS
20 FOR M=0 TO 127
30
SET (M,0)
40
SET
(M,47)
50
NEXT M
60
V
=
14
70
D
=
1
80
RESET
<64,Y+48-D)
90
SET
(64,
Y)
100 Y
=
Y+D
110
IF
Y=48
THEN
130
NOTE:
No
carriage-return-suppressing
semicolons
follow
the PRINT
AT statements
-
sloe* itoy
are
not on
the bottom print
line
:;'"
?
;V:":."
><-<}\]::,-^Z:-.'\
'.'
135
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