Cls; For M=0 To; Set (M,0); Set <M,47) - Radio Shack TRS-80 User Manual

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