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SECTION
2.
INTERNAL DATA STORAGE
2.1
FINAL
AREAS, OUTPUT
ARRAYS,
D MEMORY POINTERS
is
that portion of memory where
data
are
stored.
Data must be
sent
to
before they
can
be
transferred
peripheral.
a
computer or external storage
The size of FinalStorage
is
expressed
in
terms
of memory
lQcations
or
bytes. A
low resolution
data
point
(41
decimal characters) occupies one
memory
loc{tion
(2 bytes), whereas
a high
resolution
d{ta
point
(5
decimal characters)
requires
two memory locations (4
bytes).
Table
1.5-1
showslthe default allocation of memory
locations
to
fnput, lntermediate,
and Final
Storage.
Tfrje
"A Mode is used
to
reallocate
memory or
{rase
Final
Storage (Section
1.5).
A
minimum
of
[68
memory locations
will ALWAYS
be retained ln Final Storage.
FinalStora
can
be represented as
ring
memory
(Fi
ure 2.1-1) on which
the newest data
are written ver the oldest data.
$
=
Output
ottoy stotl
Y
moaker
output
array.
For example,
the
lD
of 118
in
Figure
2.1-2 indicates that the
18th
instruction
in
Table
1
set
the Output Flag
high.
PROGRAM
TABLE
NUMBER
I
| --
LOCATION NUMBER
OF THE
INSTRUCTION
WHICH
I I
SET THE
OUTPUT
FLAG FOR THIS
ARRAY
ll
Final
final,
01+0118
Locotion
No,
Moximum
locotiori
No,
FIGURE
2.1-1. Ring Memory Representation
of Final
Data
Storage
Output Proqessing Instructions store data into
Final Storage only when the
Output Flag
is
set
high. The
dtring of data stored each time the
Output Flag
is
set high
is
called an
output
array.
The
first data point
in
the output array
is
a 4
digit
Output Array
lD.
This lD number is set
in one
of twD
ways:
1)
ln
the
#fault
condition,
the lD consists of
the program table number and the
lnstructlon Location Number of the
instruction which set the
Output Flag for that
I L--
DATA
porNT
I
TA
POINT
ID
FIGURE
2.1-2. Output Array
lD
2\
The output array lD can be set by the user
with
the second parameter of Instruction 80
(Section
1
1).
The lD can be set to any
positive integer
up
to
511.
Instruction 80
must follow
the instruction which set the
Output Flag
high.
This option allows
the
user
to make the output array lD
independent of
the programming. The
program
can be changed (instructions
added or deleted) without changing
the
output
array
lD.
This avoids confusion
during
data reduction, especially on long
term projects where program changes or
updates
are likely.
NOTE:
lf Instruction 80 is used to
designate Final Storage and parameter
2
is
0, the output
array lD is determined by the
position
of Instruction 80 or
by
the position
of
the instruction setting the Output Flag,
whichever
occurs
last.
Data are stored
in Final Storage before being
transmitted
lo
an external
device. There
are
5
pointers
which are used to keep track of data
transmission. These pointers are:
1.
Data
Storage Pointer (DSP)
2.
Display Pointer (DPTR)
3.
Tape Pointer (TPTR)
4.
Printer Pointer (PPTR)
5.
Telecommunications(Modem)Pointer
(MPrR)
2-1
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