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Document:	VAX-11 PASCAL Installation Guide/Release Notes (Ver 1.0-1)
Order Number:	AA-J181A-TE
Revision:	000
Pages:	20
Original Filename:

OCR Text

November 1979

This document contains instructions for installing the VAX-11 PASCAL compiler on the VAX/VMS operating system. It also contains information not included elsewhere in the documentation set, typically concerning software

and/or documentation errors that were discovered or changes that were made
late in the development cycle. This document should be read before the
VAX-11 PASCAL compiler is installed or used.

VAX-11 PASCAL
Installation Guide/Release Notes
Order No. AA-J181A-TE

SUPERSESSION/UPDATE INFORMATION:

This is a new document for this
release.

OPERATING SYSTEM AND VERSION:

VAX/VMS V1.6

SOFTWARE VERSION:

VAX-11 PASCAL V1.0-1

To order additional copies of this document, contact the Software Distribution
Center, Digital Equipment Corporation, Maynard, Massachusetts 01754

digital equipment corporation - maynard, massachusetts

First Printing, November 1979

The
and

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in

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assumes

without
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Equipment

responsibility

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copied

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commitment

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may

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only

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construed

Digital

errors

may

not

furnished

accordance

with

under
the

terms

1license
of

such

license.
No

responsibility

equipment

that

assumed

not

for

supplied

the

use

by DIGITAL

reliability

its

affiliated

software

companies.

The postage prepaid READER'S COMMENTS form on the last
document
requests
the
wuser's
critical
evaluation
preparing future documentation.

The

following

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trademarks

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page
of
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Corporation:

this
us in

o
ol
Q
0]

CONTENTS

INTERFACE

THE

VAX-11l

SYMBOLIC

DEBUGGER

Choosing a Language
Describing Object Program Locations
Examining and Modifying Variables
Debugger Commands
RELEASE

NOTES

LIST Option
Rewrite of a File Using DECnet
Reinstallation of VAX-11l PASCAL
Reading REAL or DOUBLE Precision Numbers
Using Descriptors in VAX-11 PASCAL
Number

Significant Digits

Assignment of PASSINPUT and PASS$SOUTPUT
Run-Time Errors Not Signaled

[]

Output Characteristics Differ
No Checking for Dereferencing a NIL Pointer
Overflow of REALs and INTEGERs
TRUE

RUN-TIME

and

FALSE

Comparisons

ERROR TERMINATION MESSAGE

iii

Ll el

PROCEDURE

Contents of the Distribution Kit
Preparing to Install the VAX-11 PASCAL
Compiler
The Installation Procedure
Completion of the Procedure

LOWOOWOoOOWONANNUVNULEN -

INSTALLATION

[]

]

WWWWWWWWWWWLWwWWWNoNNDNDN

HFHEHEFEFOYWONAOAUGWNOFHEOWNEHODW
WO

PREFACE

MANUAL

The

OBJECTIVES

VAX-11

PASCAL

Installation Guide/Release

Notes

describe:

The procedures necessary to install the VAX-11 PASCAL compiler
on

the VAX/VMS

The

use

the

operating

VAX-11

system

Symbolic

Debugger

debugging

PASCAL

programs

Changes that were made and problems that were
discovered
too
late
in
the development cycle to be discussed in the rest of
the VAX-11 PASCAL manual set

INTENDED

This

AUDIENCE

manual

intended

for

use

by VAX/VMS

system managers

and

PASCAL

programmers.

STRUCTURE

OF THIS

This manual

DOCUMENT

organized

follows:

Section

1.0

describes

Section

2.0
to

debug

Debugger

the

installation

briefly describes how to
a PASCAL program.

Section 3.0 lists and describes
this release of VAX-11 PASCAL.

procedures.

use

the

VAX-11]

Symbolic

problems

and

restrictions

VAX~-11

1.0

INSTALLATION

PASCAL INSTALLATION GUIDE/RELEASE NOTES

PROCEDURE

This chapter describes the procedure for installing the VAX-11
PASCAL
compiler
on the VAX/VMS operating system.
The procedure is automated
and requires that the system manager or
other
individual
performing
the
procedure
mount
floppy
diskettes
when prompted and respond to
queries issued during the installation procedure.

This procedure can be performed by any system user who has
access
to
the
system
manager's
account
or
to
an
account that has the same
privileges as the system manager's account.

1.1

Contents

the

The VAX-11 PASCAL
floppy diskettes.

Distribution Kit

installation

kit

consists

three

FILES-11

ODS

Each diskette is labeled with both a serial
number
corresponding
to
the
VAX-11
PASCAL
compiler's product number and a unique label that
differentiates
that
diskette
from
every
other
diskette
in
the
distribution kit.

The

diskettes

the VAX-1ll

Diskette

Label

PASCAL V1.0
(numbered 1/3)

PASCAL

(numbered
VAX-11

These

RX01

PASCAL

V1.0

RX01]

V1.0

RX01

Preparing
prepare

the
installation
Run-Time
Library

object
object

modules,
modules.

and

This

diskette

contains

This

3/3)

for

diskette

compiler

diskettes

following

are:

some

compiler

object

must

mounted

Install

the

the VAX-11

installation

contains

object

the

remainder

order

listed

above

PASCAL

compiler,

the system console terminal, log into the
system manager's account or other privileged
sure

that

the

logical

procedure.

should

not

Note

be)

that

the

name

the

perform

the

SYS$SDISK

1is

system

using

the

account.

assigned

the

current
version
of
VAX/VMS,
as
all updates.
This
disk
contains
that
initiates
the
installation

SYSSDISK

same

during

PASCAL Compiler

VAX-11

disk
that
contains
the
distributed, and contains
the
command
procedure

the

modules.

steps:

the

modules.

installation procedure.

1.2

kit

This
diskette
contains
command
procedure,
the

2/3)

(numbered

distribution

Contents

VAX-11

PASCAL

need

not

SYSSSYSTEM.

(and

possible

VAX-11

Enter
e

PASCAL

the

following

Change

the

SET

Set

the

commands

current

UIC

directory

DEFAULT

console

UIC

the

order

shown:

follows:

[1,4]

default

SET
4.,

INSTALLATION GUIDE/RELEASE NOTES

follows:

([SYSUPD]

terminal,

type:

@QVMSUPDATE

The execution of the command
procedure
VMSUPDATE.COM
initiates
installation
procedure.
The
procedure
VMSUPDATE.COM
displays

the
the

following:

This command procedure
performs
VAX/VMS
unbundled software installations...

software

During this sequence, the standard console
present in the console floppy drive.

floppy

updates

will

not

and

Therefore, the system is vulnerable to
power
failure
or
other
types of fatal crash.
If a system crash should occur during this
period the update sequence can be restarted at the
beginning
of
the first incomplete update.
Dismount

the

current

console

Please place the first
You

are

PASCAL

1.3

now

ready to begin

floppy.

floppy of the kit
the

in the console drive.

installation procedure

for

the

VAX-11

compiler.

The

Installation Procedure

If there is a floppy disk mounted in the console floppy drive,
remove
it.
(Note
that
if
there is no floppy diskette mounted, the system
displays an error message.
You can ignore this message and continue.)
When you remove the floppy diskette, note the direction it is
facing,
that
is, the direction of the label on the diskette.
When you insert
diskettes from the distribution kit, you must insert them in the drive
so that they face the same direction.
(The label is on the front side
of

the

Place

diskette.)

the

receive
ARE

If you

first diskette,

the
YOU

READY

type Y

continues.

labeled

1/3,

the console drive.

You will

message:
TO

CONTINUE?

response

this message,

the

installation

procedure

VAX-11 PASCAL INSTALLATION GUIDE/RELEASE NOTES
If you type N, the request to place the first diskette in the
console
floppy
drive and the query "ARE YOU READY TO CONTINUE?" are repeated.

When you have responded "Y" to the query, the command procedure on the
first
floppy
diskette
assumes control and the files needed to build
the compiler are copied from the first diskette to
the
system
disk.
When this is done, you receive the next messages:
PLEASE
IF

ARE

PUT THE
MORE

YOU

FLOPPIES

READY

PASCAL
TO

KIT

FLOPPY

COPIED,

DISK

PLEASE

TYPE

THE

DRIVE.

<CR>.

CONTINUE?

Replace the diskette labeled 1/3 with the diskette
labeled
type Y to indicate that the installation can continue.
When

this

stage

PLEASE
IF

ARE

PUT
MORE

YOU

complete,

THE

FLOPPIES

READY

you

PASCAL
TO

receive
KIT

the

FLOPPY

COPIED,

TYPE

THE

this

stage

PLEASE

ARE

PUT

YOU

FLOPPIES

READY

you

PASCAL

receive
KIT

During

3/3

the

out

the

FLOPPY

COPIED,

messages:

DISK

PLEASE

TYPE

THE

DRIVE.

<CR>.

CONTINUE?

Since you have completed processing all
return
instead
of
a
Y
this
time.
labeled

and

<CR>.

CONTINUE?

complete,

THE

3/3,

DRIVE.

Replace the diskette labeled 2/3 with the diskette
1labeled
type Y to indicate that the installation can continue.
When

and

messages:

DISK

PLEASE

2/3,

the

drive

following stage,

any

the floppies, type a
carriage
You may now take the diskette

time.

you will

get a

warning

message

"PASCAL"

multiply defines

from

the

linker:

$LINK-W-MULTFR,

This

normal

message

will

The
DO

message and

should

ignored.

Then

transfer

the

address

following

appear:

default
YOU

Module

WANT

linelimit

IT?

CHANGE

the

compiler

2**31,

Respond with N if you do not wish to change
the
1linelimit.
If
you
wish
to
impose a smaller default linelimit on files generated by the
PASCAL I1/0 system, then respond with ¥, in which case the next message
you will

What

see

is:

linelimit

you want

have?

VAX-11 PASCAL INSTALLATION GUIDE/RELEASE NOTES
Respond with the positive decimal integer value you wish
to
have
as
the default linelimit.
(For example, typing 100 sets the linelimit to
100 lines.) When this stage is complete, you will receive the message:
DO

YOU

WANT TO

PURGE

OLDER VERSIONS

OF THE

PASCAL

COMPILER?

Type Y if you wish to delete older versions;
type N if
you
wish
to
retain older versions.
If you have not previously installed PASCAL on
the

system,

type N.

You

may

receive

now

some

the

following

MODULE

"PASSIO_BASIC"

REPLACED

MODULE

"PASSIO_INPUT"

REPLACED

MODULE

"PASSIO_OUTPUT"

MODULE

"PASSRT _UTIL"

REPLACED

MODULE

"PASSRT HEAP"

REPLACED

MODULE

"PASSRT_ CHK"

REPLACED

MODULE

"PASSRT_FUNC"

REPLACED

MODULE

"PASSLINELIM"

REPLACED

PASCAL ALREADY APPEARS

$SYSTEM~-F-DEVNOTMOUNT,

device

These

messages

should

messages:

[SYSHLP]HELP.HLP

- NOT

INSERTED.

not mounted

ignored.

At this time, an installation verification test
will
be
run.
This
test
compiles, links, and executes a sample PASCAL program.
The only
output

the

PASCAL

1.4

terminal

INSTALLATION

Completion of

When the
system

will

be:
SUCCESSFUL

the Procedure

installation procedure
completes,
control
returns
to
command
procedure
VMSUPDATE,
This
procedure
1issues

the
the

following message:

ARE THERE MORE KITS TO PROCESS

[Y/N]

Respond with a Y to this message only if you have additional
software
kits
to
install.
Then you will receive a request to mount the first
diskette from another distribution kit.
The installation of that
kit
will

continue.

If you

type N,

you will

Please place

receive

the

the system console

message:

floppy

You should immediately restore the standard
was
removed
at the beginning of the update
drive.

the console

drive.

console
diskette
(which
procedure) to the console

VAX-11

After

you

have

PASCAL

replaced

INSTALLATION GUIDE/RELEASE NOTES

the

system

console

diskette,

you

receive

the

message:

ARE

Y.
receive

YOU

Type

READY

The

the

console

floppy diskette

update

IMPORTANT NOTE:
manager

The

CONTINUE?

automatically

mounted.

You

message:

Requested

system

sequence

Upon
must

following

complete.

completion

perform

two

the

system

the

following

logical

installation

names

ASSIGN/SYSTEM

SYSSOUTPUT

ASSIGN/SYSTEM

SYSSINPUT PASSINPUT

process,

the

task:

must

established:

PASSOUTPUT

These two assignments must also be
placed
1in
[SYSMGR]SYSTARTUP.COM.
They establish the default INPUT and OUTPUT files for PASCAL I/O.
The
VAX/VMS software release distribution kit version
of
SYSTARTUP
will
eventually
include
these
commands,
but
until
then,
they must be
treated

The

site-specific

VAX-11

PASCAL

start-up

compiler

commands.

now

installed and

can

invoked

the

command:

SPASCAL

2.0

The

INTERFACE

VAX-11

THE

Symbolic

VAX-11

Debugger

SYMBOLIC

DEBUGGER

does

currently

features

support

PASCAL.

commands

that

supply

high-level

when
your

debugging
PASCAL

assembly
PASCAL

PASCAL

program

language
©program,

object
the

same

program.
you

not
This

contain

any

special

many

the

debugger

that

lanquage

support

are

modules.

However,

you

manner

Before

should

means

you

would

attempting

familiar

with

use

not

can

available

still

debug

the

debug

MACRO

debugger

VAX

instruction

architecture.

This section assumes that you
are
familiar
with
using
the
VAX-11
Symbolic
Debugger.
If you are familiar with MACRO assembly language
programming, but have not used
the
debugger,
you
should
read
the

VAX-11

Symbolic

understand

2.1

this

Choosing

Debugger

you

invoke

However,

the

1is

knowledge

BLISS

language

set

Manual

allows you to
convenient.

debugger,

advised
and

this

the

way

the

that

language

only

VAX-11l

for

choose
the
The current

those

Symbolic

debugging

DOUBLE

types.

However,

the

attempting

FORTRAN

debugger
command
choices are BLISS,

initially

individuals
Debugger

PASCAL

If you choose FORTRAN, the debugger will
assignments
containing
simple variables
and

before

Language

The SET LANGUAGE command
formats
that
are
most
MACRO, and FORTRAN.
When

Reference

section.

set

with

should

BLISS.

detailed

1leave

the

programs.

understand
expressions
and
of the INTEGER, REAL, SINGLE
language

mode,

the

debugger

VAX-11

does

not

allow

difficult

debugger

PASCAL

you

examine

FORTRAN

INSTALLATION GUIDE/RELEASE NOTES

address

structured

mode.

FORTRAN

mode

Your program contains
SINGLE and DOUBLE).

You do not
records).

You need to set break points
functions and procedures.

MACRO

mode

allows

need

many

examine

and

simple

useful

only

(INTEGER,

the

REAL,

(arrays

entries

vyour

You
you

should

the

language

mode

the

way

MACRO

and

same

choose

variables

with

if:

variables

structured

result,

code

variables

structured

object

that
you
would
examine structured data in an assembly program.
can also easily examine the object code instructions.
Therefore,
probably

you

arithmetic.

variables

use

with

debugger.

For information about using the debugger with MACRO assembly programs,
refer
to
the
VAX-11
Symbolic Debugger Reference Manual.
Using the
debugger with FORTRAN programs 1s
described
1n
the
VAX-1l1
FORTRAN

IV-PLUS
programs

2.2

User's
Guigde.
is included in

Describing

Object

Information on using the debugger
the VAX-11l BLISS-32 User's Guide.

Program

with

BLISS

Locations

PASCAL produces its machine code listing
before
it
performs
branch
optimization.
Therefore,
the
hexadecimal
1locations in the machine
code listing do not correspond to the locations in
the
final
object
code.
As
a result, you cannot safely set a break point based on the
locations specified in the listing.
However, you
can
easily
set
a
breakpoint
at
the
entry
of
a procedure or function.
By using the
EXAMINE/INSTRUCTION command, you can look at the
actual
object
code
and use this information to set break points inside routines.
PASCAL
and
the

produces

line

number

the
debugger.
When you
SHOW CALLS command), you

procedure

calls

have

table

for

use

the

traceback

examine the stack of
can
see
the
1line

occurred.

However,

the

routine
numbers

debugger

program

calls (with
where
the

currently

only

allows line number tables produced by FORTRAN to be used as input.
1If
your
PASCAL
program does not contain any procedures, the object code
is similar enough to that produced by FORTRAN
so
that
you
can
use
$LINE parameters with debugger commands in FORTRAN mode.
But for most
PASCAL programs, the SLINE parameter will not
be
available
for
use
with
the
current
debugger.
Furthermore, you cannot use the %LABEL
parameter

because

PASCAL

labels

not

1look

1like

FORTRAN

statement

numbers.,

2.3

Examining and Modifying Vvariables

PASCAL

generates

REAL,

©SINGLE,

commands

work

complete

symbol

and

DOUBLE

easily

with

table

types.

The

wvariables

entries

only

EXAMINE,

these

for

the

INTEGER,

EVALUATE,

and

types.

When

DEPOSIT

using

variables
of
other
types,
you
must
be familiar with the internal
format that PASCAL
uses
to
store
these
types.
PASCAL
generates
debugger
symbol table entries for all variables, but the symbol table

entry for a structured variable currently gives
only
the
variable's
location.
As
a result, the debugger always prints storage allocated
to a variable as
an
unsigned
numeric
value
using
the
debugger's
prevailing number base.

VAX-11 PASCAL INSTALLATION GUIDE/RELEASE NOTES
Because PASCAL is
a
block
structured
1language,
you
may
find
it
necessary
to
provide
extra
qualification
to your program's symbol
names.
For example, if variable NAME is declared in procedure PROC in

program
input

debugger

PROG,

and

this

then

output

variable
the

NAME

should

debugger.

This

to differentiate this use of the
symbol elsewhere in your program.

appear

PROG\PROC\NAME

qualification
symbol

NAME

from

allows

the

other

uses

PASCAL does not nest its procedure symbol tables.
Thus, even
1if
vyou
declare
a
procedure
INNER
1local to a procedure OUTER, the produced
symbol table describes both INNER and
OUTER
as
unnested
procedures
declared
in
main
program
block.
As
a
result, you never need to
qualify a variable name with more than two context names (the
program
or module name and the procedure name).
Variables declared in the outermost block look like they were declared
in
a
procedure
with
the
same
name
as the program.
Therefore, a

variable with the name NAMEl
declared
1in
program
PROG
PROG\PROG\NAME1 when used with the debugger.
The scoping
debugger
VAX-11

usually
Symbolic

make

this

qualification

Debugger

Reference

unnecessary.

Manual

these
debug

for

scoping rules work.
However, since PASCAL
symbol
tables,
the
.debugger
sometimes
procedures with identical names.

appears
rules of

Refer

description

as
the
the
how

does
not
nest
its
confuses two internal

The current version of the debugger does not
reconstruct
the
proper
context
when
accessing
a
variable.
You
must
issue a SHOW CALLS
command to determine which PASCAL routine is uppermost in the stack of
called
procedures.
You
can
then
examine
variables
only in this
uppermost procedure and in the main program block.
If
your
program
references
variables
declared in outer blocks (other than at program
level), the debugger accesses the wrong location.
PASCAL statically allocates the variables in the outer
main program so that you can examine these variables at

2.4

Debugger

debugger commands
work
Debugger
Reference
Manual,
exceptions.
CALL

the

Commands

Most

1level
of
any time.

Although

by-reference,

and

described

The

FORTRAN

the

CALL

and

always

debugger

1in
the
VAX-1ll
Symbolic
STEP commands are the two

passes

considers

MACRO

parameters

use

call

by-value, PASCAL allows a mixture
of
<call
by-reference
and
call
by-value (as described in Chapter 6 of the VAX-11 PASCAL
User's Guide).
1In addition, PASCAL uses its
own
conventions
when
passing
procedures
and
functions
as
parameters.

Therefore, you must
carefully
consider
the
effect
of
the
debugger
1language
mode
when
using the CALL command to call
PASCAL routines.
Use
the
CALL
command
only
if
you
are
familiar
with
the
run-time representation of parameters for
PASCAL functions and procedures.
@

STEP
LINE
also

—-- The STEP command works in INSTRUCTION mode, but not in
mode.
If you select the FORTRAN language mode, you must
issue the SET STEP
INSTRUCTION
command
after
the
SET

LANGUAGE

command.

VAX-11

3.0

PASCAL

INSTALLATION GUIDE/RELEASE NOTES

RELEASE NOTES

The

following

the

operation

the

3.1

summary of
VAX-11

all

the

PASCAL

known

restrictions

that

affect

compiler.

LIST Option

The /LIST
command
line
qualifier
does
not
work
as
expected
in
connection
with
the (*L+*) source code qualifier.
This is due to an
error in the way the VAX/VMS command line processing works.
For now, you must explicitly specify /LIST
want a source code listing, as follows:

SPASCAL/LIST=file-spec

the

command

line

you

file-spec

SPASCAL

file-spec/LIST=file-spec

If you specify neither /LIST nor
/NOLIST,
the
compiler
behaves
as
though
you specified /NOLIST.
Therefore, attempts to set the listing
option in the following format within a
PASCAL
source
program
will
have no effect:

(*$SL+*)
A future
problem.

3.2

Rewrite of

There
a

release

remote

the

File Using

restriction

(not

VAX/VMS

local)

operating

will

correct

files

that

this

DECnet

concerning

node

system

the

DECnet

rewriting

exist

network.

A new file can be created and written on a remote node through
VAX-11
PASCAL.
An
existing file can be read but not rewritten unless it is
empty.

The

following
OPEN

(FILEX,

REWRITE

WRITE

code

sequence

will

'BANGOR"PLUGH

fail

MASTER.DAT

XYZZY"::MASTER.DAT',

not

empty:

OLD);

(FILEX);

(FILEX,

VAR1l,

VAR2);

When you call REWRITE in VAX-11] PASCAL, the file
buffer
variable
is
set
to
the
beginning
of
the
file
and
all
existing records are
overwritten and therefore lost.
You
could
also
open
the
file
as
"NEW",
in
which
<case
the
previous
version
of
the
file
1is not
destroyed, but a new version is created.
The
result
1is
the
same,
except that the file's version number has been incremented.

This

stems

future

from a

restriction

DECnet-VAX

that

will

fixed

release.

(For a discussion of "NEW" and "OLD" files, see
Section
7.5
of
the
VAX-11 PASCAL Language Reference Manual concerning the OPEN statement.
An example of writing data to a remote node is shown in Section 5.6 of
the VAX-11 PASCAL User's Guide.)

VAX-11l

3.3

PASCAL

INSTALLATION GUIDE/RELEASE

Reinstallation of VAX-11l

NOTES

PASCAL

The VAX-11 PASCAL compiler must be reinstalled
after
a
new
VAX/VMS
operating system is generated.
A new system generation will produce a
new

copy

the

library

PASCAL

modules.

library

only

3.4

Reading

When

you

READLN,

The

the

REAL

read
the

The

are

will

not

contain

modules

can

VAX-11

the

written

VAX-11
into

the

READ

PASCAL.

DOUBLE Precision Numbers

exponent

following

which

specific

reinstallation

REAL

STARLET.OLB
PASCAL

DOUBLE

values

designator

must

illegal

values

using
be

the

procedure

capital

letter,

"E"

"D."

input:

lel

3.1415e0
10.11114-3

This problem will
operating system.

3.5

Using

VAX-11

fixed

Descriptors

PASCAL

uses

in VAX-11

the

uniform

future

release

descriptor

mechanism

in languages
descriptors,

However,

there

use

PASCAL.

The

not

be filled
fields.
It
directly.

3.6
The

Number
number

VAX-11

in.

of
of

type

the

fields

This is due to a
not
recommended

printed

for

Typically,

the

functioning

that

('The

the

program:

value

digits

',X ) [4

',X:16:9)

)

WRITELN

('eight

digits

',X:16:8

WRITELN

('seven

digits

WRITELN

('six

',X:16:7 ) ’

WRITELN

('five

END.

VAX-11

some

arrays may

the
size
fields
be

of
these
referenced

single-precision
however,

3.14;
('nine

descriptors

these

REAL;

WRITELN

deficiency

BEGIN

WRITELN

transmitting

other than PASCAL.
see Appendix C
of

descriptors

TESTFP (OUTPUT) ;

VAX/VMS

Digits

1is

following

PROGRAM

VAR

and

digits

significant due
the

restriction

Significant

PASCAL

Consider

the

PASCAL

$DESCR
arguments
to routines written
(For a complete discussion of argument
the VAX-11 Architecture Handbook.)

length

digits
digits

’
.

',X:16:6);
',X:16:5)

only

VAX/VMS

real

these

hardware.

number

digits

are

VAX-11

The

output

PASCAL

from this

The value of X
nine digits
eight digits
seven digits
six digits
five digits

When doing precise
degree of

3.7

error

INSTALLATION GUIDE/RELEASE NOTES

program would

be:

is 3.140000105E+00
3.140000105
3.14000010
3.1400001
3.140000
3.14000

arithmetic

calculations,

you

should

keep

this

in mind.

Assignment of PASSINPUT and PASSOUTPUT

The assignment of PASSINPUT and PASSOUTPUT to SYSSINPUT and SYSSOUTPUT
is
specified in the installation section of this manual.
versions of VAX/VMS later than 1.6, these assignments may
present in the system startup command procedure file.

However,
already

on
be

The reassignment of PASSINPUT and PASSOUTPUT at installation time will
then
be
unnecessary.
If performed, reassignment will have no effect
and the compiler will continue to function correctly.

3.8

Run-Time Errors Not Signaled

Errors at run time from the VAX-11 PASCAL compiler cannot
be
fielded
by
condition
handlers
(see
Chapter
7
of the VAX-11 PASCAL User's
Guide).

future

errors

3.9

release of the
they may

VAX-1l1

fielded

PASCAL

compiler

condition

will

signal

these

handlers.

Output Characteristics Differ

The predeclared files INPUT and OUTPUT (SYSSINPUT and SYSSOUTPUT)
are
opened
with
default
attributes.
However,
OUTPUT is not opened in
exactly the same manner as is done in other
VAX/VMS
languages.
For
more
information on the predeclared file OUTPUT, see Chapter 7 of the
VAX-11

3.10

PASCAL

Language

No Checking

Reference

Manual.

for Dereferencing a NIL Pointer

When the CHECK qualifier is set at compile time,
VAX-11]
PASCAL
does
not
generate
code
to
<check
for
dereferencing
a
NIL
pointer.
Currently, an access violation occurs when a
program
dereferences
a
NIL pointer.

To avoid the problem at this time, you can check for
dereferencing
NIL pointer in the source program by writing a routine to do so.

VAX-11

3.11

Overflow of

There

REAL

and

For

PASCAL

REALs

restriction

INTEGER

INSTALLATION GUIDE/RELEASE NOTES

and

INTEGERs

the

example,

consider

the

PROGRAM

TOOLARGE

(INPUT,

VAR

BIG

diagnosis

overflow

conditions

for

numbers.
following

program:

OUTPUT);

REAL;

BEGIN

READ

(BIG);

WRITE

(BIG)

END.

When

this

program

run

and

the

following

number

entered:

1.8E39

The

following

result

is printed:

0.000000000E+00

This problem will
compiler.

3.12

TRUE

and

fixed

future

release

the

VAX-11

PASCAL

FALSE Comparisons

VAX-11 PASCAL uses more than just the
low-order
bit
when
comparing
Booleans.
This will cause incompatibilities with Boolean values from
FORTRAN IV-PLUS, system services, and other VAX/VMS languages that
do
not

3.13

use

for

RUN-TIME

FALSE

and

ERROR

for

TERMINATION

One of the following messages
an error at run time:
$PAS-F-NOMSG,

Subsystem

¥NONAME-F-NOMSG,

TRUE.

MESSAGE

may

appear

when

Message

Subsystem

The

message appears along with
other
provide
more
information
about
the
change in a future release.

your

number

Message

program

encounters

33700

number

33668

run-time
error
messages
error.
These two messages

that
will

VAX-11

PASCAL

Installation

Guide/Release Notes
AA-J181A-TE

READER'S

NOTE:

This

use

form

comments

discretion.
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COMMENTS

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service,

only.

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this manual understandable,
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