A
ll
and more about Sharp P
C-
1500 at http://www.PC-1500.info
Now
r,
1n the revised program. What happens? Press l•
•<T<•
I after "JOLLY" appears.
Notice in this
example
both
what SHARP has
done
for you and what
you
have had
to
do
for
YQYrself,
SHARP
has
arran
ged
and
ex~Yted
li
nes
5
and
10 in
the
pro
pe
r o
rd
er.
Yet, to
midge
SHARP
on
from line 5 to
10
,
to
sec the result
of
line
10
,
you
have
to
press ENTER between
outputs.
Although a
li
ne number may
be
any number from 1 to 65,279, we strongly advise you to
nu
mber
your
lines by increments
of
10 (i.e. 10,
20,
30,
···
etc.}. This allows you to insert up
to
9 statements between
your
current statements (11 through 19, for instance).
So
me programmers
recommend
an
even greater
gap
; numbering by 20's. Although,
wi
th careful program design and
writing, you \viii rarely need
to
in
se
rt
statements,
do
not count on th
is!
It
is
fi:lr
easier to nu
mb
er
by
1
O's
now
than
to
renumber
1nany
stat
ement
s lat•er.
Remember that no t\"10
lines
may
have
the
same
li
ne
number.
If
this
condition
should
occur,
the oldest line
(the
one
entered first) will be lost. This feature can be
exp
loited
to
delete
unwanted lines merely by keying the line number
of
the line
to
be deleted
and
pressing I
EHTER
I •
Thus, an empty,
yet
numbered, line will
effectively
delete
an
existing li
ne\vi
th
the
same number.
If
duplicate line numbers arc used unintentionally, however, trouble wi
ll
result.
To
demonstrate this,
en
t
er
the following line (in
PR
Og
ram mode,
of
course):
Keystrokes:
m w m
oo
m
oo
rn
1 s •• ,,1
c:i
m
CID
m
OD
m
I SHIFT I
c::J
! ENTER!
Now run the program in
the
same way you did before.
It
is
"JOLLY
AWFUL" to loose a
program
li
n
e,
isn't it? And since line loss
can
le
ad
to some very subt
le
errors,
you
should exercise
caution in writing
your
programs.
E. PROGRAM·LINE REVIEW keys
"
But"
, you mig'ht ask yourself,
"How
can I remember what
lin
es I have
entered?".
Fear
not
intrepid p
ro
grammer! This need
to
rcvievv has
been
anticipated and provided for
\Vith
the CO
(U
p Arrow) and
CJ]
(Down Arrow) keys. You may think
of
these as
the
Program.line Review
keys.
By
pressing
the
appropriate key (in PROgram mode},
one
may "move"
up
o r down through
the
lines
of
the
current
program (a process known appropriately as
"sc
rolling").
Switch to the P ROgram mode and use
the
Down A
rr
ow
key to review
the
lines
of
our
program
in ascending order. Now use
the
Up
Arrow key
to
move back
to
the
top
of
the program (line 10).
Note
that
if
either
Arrow key is held down, successive li
nes
will be displayed automatically,
(Unfortunately, thi's feature
is
not
easily seen with a two line program).
Once
you
have reached a given line using
the
Program·line Review keys, you may then proceed
to edit
that
line using
the
Right
or
Left Arrow keys. You will be delighted (relieved?)
to
discover
that
the
operation
of
these keys in
the
PR
Og
ram mode
is
identical
to
their operation in the
AUN
mode (see Chap
ter
21.
The DELete and INSert functions are also available for use in statement
editing, and
are invoked in
the
same manner
as
before.
NOTE:
That
after any changes are made to a program line,
you
must press ENTER in order
to
affect those changes. DO
NO
T use
the
Up
or
Down Arrow keys
to
move
on
to th
e next
ad
jacent
line without pressing l
•NTE•
I
or
any editing you may have performed will be lost.
26
Do
not sale this PDF
!!!
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