Radio Shack TRS-80 User Manual page 41

. . .
and the
answer
will
be
3583
With
no program
loaded, there are
3583
memory
locations available for use.
The
difference
in
memory
space
between 3583 and 4096
is
set aside for processing programs and
overall
management and "monitoring"
of
what
the
Computer
is
doing.
Type
in this
simple program:
10
A =
25
then measure
the
memory
remaining
by
typing
PRINT
MEM
. .
.
the
answer
will
be
3573
The
program
you
entered took 3583
—
3573
= 10
bytes of space. Here
is
how you
can
account
for
it:
1.
Each
line
number
and
the space following
it
(regardless of
how
small or
large
that
line
number
is)
occupies
3
memory
cells.
The
"carriage return"
at
the
end
of the
line
takes
1
more byte, even though
it
does not
print
on
the screen.
The memory
"overhead"
for
each
line,
short or
long,
is
4 bytes.
2.
Each
letter,
number
and
space takes
1
byte.
In
the above program 4 + 6
=
10 bytes.
Enter
this
additional
line,
leaving
in line 10,
and
calculate the
amount
of
space remaining
in
memory. Then
check
it
with the
PRINT
MEM
command.
20
PRINT "THIS EXAMPLE
IS TH
MEASURE MEMORY USAGE."
How
much
space
is
left in
memory????
..
Answer: Line
10 took
up 10
bytes. Line 20 takes 4 bytes for "overhead"
+ 48
characters
52
bytes.
52 + 10 =
62
bytes,
3583
—
62 = 3521
bytes.
Type
CJR01S:
H
you
don't get
this
answer
(fosr
example
as
:very large
number
or
one
wiih
a
—
iait^iurn
tfte
/
Computers
POWER
off
for at least 1$
second
and then
turn
it
on
again.
Try
PRI
NT MEH
once more.
[If
your
TItS*330 has more
RAM,
you
>
can expect a
larger
number,
as follows:
.
8K RAM:
7679 :.:^-M
:
;.^i^RAMpi^7!^;--
'-;:;
>^f
!>:.-
.
::^ ;
'
;
;
;
4j
:
-$if
te
:
T7T
:
fe
the
basic
unit of storage for most
l
„
...
:;iJsteis;
normally
it is
considered as
a
staring
of
eight-;
binary
digjts (MtsjL
Thus a byte
=?.
8
bits.
39