Campbell 21X Manuale dell'Operatore Scaricare il pdf (Pagina 36)

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

1 2 ... 31 32 33 34 35 36 37 38 39 40 41 ... 190 191

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