Goto - Radio Shack TRS-80 User Manual

The change
in
direction
of the
moving dot
is
caused
by
line
140 D=-D, Note
that
we must
be
careful
not
to accidentally erase part
of the boundary.
To
do
this,
we
not only
move
the
dot back
2 steps
with
line 130 {after
moving
it
forward
1 in line
100) but
we
also
return to
the
SET
in
90, rather
than
to
RESET
in
80. Tricky, tricky.
You
can
kill
the
whole day
messing around with
this
silly
bouncing
ball.
Rather good
resilience,
eh?
Real
Moving
Pictures
We
can
draw
whatever
figures
we
like. Let's try
a
stick
man.
First, his legs:
10
CLS
20
X=64
30 FOR K=0 TO
7
40
SET (X+K.40+K)
50
SET (X-K.40+K)
60 NEXT
K
999
GOTO 999
and
RUN.
Then
add
his
body
and
arms:
70
FOR K=0
TO
5
80
SET(X+K,34+K>
90
SET(X,34+K)
100
SET(X-K,34+K)
1
10
NEXT
K
and
RUN
.
And
finally his
head:
120 SET(X,32)
"I'M
A LEG MAN,
MVSE1F."
119