A
ll
and more about Sharp PC-1500
at
http://www.PC-1500.info
Congratulations!
Your
first
BASIC
progr8m
is
now
running,
Your
ir'lstruct
ions
are
being
followed and th.e
computer
is
busy listing
all
the
positive odd numbers.
in
order.
"So,"
you say to yourself,
"I'm
a genius.
Bu
1t w
he
n
..
viii
it
stop?"
Well,
. .
..
unfortunately, i,vithout your
int
e
rv
ention
or
battery failure, this p
ar
ticular program
w i
ll
never finis
t\
.
To
sec
why,
let's review our program:
10
A
~
1
20
PAUSE A
30
A=A
+ 2
40
GOTO
20
The
effect
of
the line numbered
40
is
to
cause
the
computer
to
re-p
er
form all lines
after
th
e one
numbered
20
. Th
is
includes line
40
which, of cour
se,
tells the computer to re·rc-pcrform lines
20.
30, and
40
....
and
so
on forever. This repetition without end
is
known in computer jargon
as
"
loop
ing".
Our
program
is
stuck in an "infinite
loop"
and only you have the ability·
to
stop
this tragic
expense
of
battery
power.
To
do
this, press t
he
i
ON
lkey. Since the PC·1500
is
already
on,
you
are
actually selecting the BREAK function.
Don't
be alarm
ed
. Oespite
what
t
he
name seems
to
indicate, this
is
not a self-destruct key.
As
a matter
of
record, you cannot, in any way, hurt or
damage
the
computer
merely
by
pressing keys.
so
feel free
to
experiment!
If
yo
u have pressed
the
BREAK key, a message similar
to
the following is visible in the display
\V
illdO\
V:
[
:E:F.:EAK
It·~
RUN
•
This informs
you
which
instruction
was
being
"executed
",
or
worked
on.
\Yh
en
you
interrupted
the computer.
Press
the
BREAK
key once more. and the computer a
..
vaits
your
next instruction:
[ >
Dtc
RUN
Fo
r t
hose
of
you
who
just remembe
red
that
you
left
t
he
tap running
at
home, this is a good
stopping
point
. (Before leaving, please press
the
lo•F] key
to
conserve batteries.) Others
of
you
are already becoming programming addicts and will want
to
continue your education with our
second example. (We hereby \vaive responsibil
ity
if you're late
for
dinner).
Example 2
To
begin
ou
r
second
program
it
is necessary
to
enter
the program
mode
by pressing the MODE
key until
the
letters PRO (short for PROGRAM) replac-e
the
lette
rs
RUN at
the
top
of
the display.
The
PC
·
1500
will now let us submit a new program
or
modify an old progra
m.
Because
ou
r new
program will
not
build
on
th
e instructions
of
our
old program. we
must
clear those instructions
from the
computer's
memory.
To
do
this,
type
in
the word
NEW
and pres.s ENTER. After a
pause
the>
c
ha
racter {called a prompt] will
retur
n. "·: • ·
Type
the
following keystrokes
to
enter
the first
li
ne
of
the program:
rnrnrn
CKJffi
OD
COl
sHIFT
I c::imco
!IJCD
l•
••Cf
l
(I]o:Ja:J(I)
l
s.<1n
l
[L)
I
SHIFT
I
c:::J
!
S><o
rt
f
(I)
ffi
IENTERJ
9
Do
not sale this PDF
!!!
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