Radio Shack TRS-80 User Manual page 113

Getting the
hang of
it??
Great.
Enough
playing
with blocks
. . .
let's
draw some
lines (really
moving
on,
eh?!).
Erase the resident program.
We'll start
with a straight
line.
This program
gives us a straight horizontal line across the
entire screen.
Type:
10
INPUT
" VERTICAL ADDRESS
(0
TD
47)"
;Y
20
CLS
30
FDR
X
=
TD
127
40 SET (X,Y)
50
NEXT
X
99
GOTO 99
andRUNseveral
times.
We
can just as easily create a straight vertical line.
Try
this.
10
INPUT ''HORIZONTAL ADDRESS
(0
TO 127)
"
S
X
20
CLS
30
FOR
Y =
TO
47
40
SET
(X, Y)
50
NEXT
Y
99
GOTO
99
And RUN
this
a
number
of times.
Now,
let's
see
if
you
can
modify
this
last
program
so
we
can
INPUT
both the
starting
verti-
cal
address
and
the length
(in
blocks) of
the
line.
Of
course you
haven't forgotten
how
to
<iojBi$fc:;
:
have yoa!.^ypeBBA§E..'
T
-.»
m,
no^no!
;T£pe
;
^-
;
;:
MEW
or just
N
.
(Don't
fotgiffc
tfcfe
period
wfeeltt.'-
yap
use abbreviations,)
111