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APPENDIX
J.
MDOS 3.00 Differences
The rollowing appendix contains
a
description
of
the
diTrerences
between
MDOS
3.00
and prior versions or MDOS.
The first part of the
appendix
contains
those
differences
that
may
have an impact on user-written programs which were
based on prior versions of MDOS.
The
second
part
oT
the
appendix
contains
the enhancements that are apparent to the
operator at the MDOS command level.
These enhancements
have
been
separated
by
the version number of MDOS in which they
~irst
appeared.
All
of
the
listed
enhancements
are
incorporated into MDOS 3.00.
J.
1 Impact of MDOS
3.00
on Previous MOOS Programs
MOOS version 3.00 accommodates both the single-sided and
the double-sided diskettes,
a
four-drive system,
an.d
multiple
sector
.1/0.
There
are
several items which as a result of
these
new
features must be checked in all programs that
have
been
~eveloped
to
use prior versions of MDOS.
These items
a1'e listed below.
1.
A
program making explicit
checks
for
logical
unit
numbers
0
and
1
must be changed to accommodate the
new numbers 2 and 3.
2.
A program referring to the maximum number of
sectors
on
a
diskette
as
2000
(decimal)
or
2002,
or the
symbol from the MDOS equate rile
(SC$MAX),
must
be
changed
to
accommodate the possible larger diskette
sizes that
can be
encoun~ered
with
the
double-sided
systems.
Once
a
diskette
has
been accessed,
the
diskette
cont~olle~
va~iable
SIDES
(location
$OOOD)
will
have
bit
seven set or cleared to indicate the
number of sides· on the diskette.
If
bit
seven
is
one,
a
single-sided diskette has been accessed.
IF
bit seven is zero,
a
double-sided d·iskette
has
been
accessed.
This
variable
is set up properly in all
versions of the MDOS diskette controller,
A
single-sided
diskette
can
be
accessed
in
a
double-sided
drive;
however,
a
double-sided diskette
cannot be accessed
in
a single-sided drive.
A
new symbol has been placed
into
the
MOOS
equate.
file
that
gives
the maximum number of sectors on a
double-sided diskette
(SCSMXD).
Page
J-Ol
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