Radio Shack TRS-80 - Page 121

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