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~ENER
AL SYSTEM OPERAT I ON
2.6 -- Common Error Messages
31 is the same as El
32
is
the same as
E2
39
is the same as
E9.
A
memor~
address
(only
meaningful
for
s~stem
diagnostics)
is
substituted .par the letter
"hili
the
d~ive
number is substituted
for
the
letter
I'i";
and
the
physical
sector
number
(PSN) at
which the error occurred is substituted
for
the
1
etter
II
J ".
2.7 Diskette File CQncepts
In
MDOS,
a diskette file is a set of related information
that is recorded more or less contiguously on
the
diskette.
The
information
can
be
actual
machine
instructions that
comprise a command or user program.
The information can also
be
textual
data,
object
program data,
or any of the Torms
described in Chapter
24.
The following section describes how
files are named,
created,
deletedl and protected.
2.7.1
File name specifications
An MDOS
file name specification consists of three parts:
a "file name", a "suffix", and a "logical unit number...
File
names
can
be
from
one to eight alphanumeric characters in
length,
the
first
oT
which
must
be
alphabetic.
The
alphabetic characters must be
uppe~
case letters.
Valid rile
names could look like the following:
DIR
ASM3870
BACKUP
50'
BLOKEDIT
Z
In most cases, all that need be specified
when
a
file
name
specification
.~
called
for
is
the
~ile
name.
The
suffix and logical unit
numbe~
are usually given
appropriate
default values
by
the various commands.
The
suffix
can
be
either
one
or
two characters in
length.
Like Tile names,
suffixes must begin with
an
uppe1'
case
alphabetic. character.
T~e
rest
or
the suffix must be
alphanumeric.
A suffix is used
to
explicitly
refer' to
a
par tic
u 1
a r e
n
t r
\I
in
the
d
ire
c
tor
\I .
Th a t i s
I
the
l'
e ma
y
b
e
several
ent~ies
with the same file name
but
with
different
suffixes.
In
such cases, a file name reference alone would
Page
02-12
,.~
)
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