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SYSTEM
DESCRIPTION
24. 1 -- Diskette Structure
Single-sided
Double-sided
Quantity
Decimal
Hex
Decimal
Hex
---.---.-.----
-------
-------
Surfaces/diskette
1
1
2
2
BytesisectoT"
128
80
128
80
Sectors/tl'ack
26
lA
26
lA
TracksicylindeT'
1
1
2
2
Sectors/c~linder
26
lA
52
34
Cylinders/diskette
77
4D
77
4D
Sectors/surface
2002
7D2
2002
7D2
Sectors/diskette
2002
7D2
4004
FA4
Sectors/cluster
4
4
4
4
Clu5ters/disiette
500
lF4
1001
3E9
MDOS
accesses sectors on the
diskette
via
a
phqsical
sector number (PSN).
The diskette
contTolle~
decodes the PSN
into
the
appropriate
cylinder/sector
position.
To
avoid
confusion,
all
sector
numbers
given
in this section will
refer to physical sector numbers.
If
a need should arise
to
convert
between cylinder/sector and physical sector numbers,
Appendix
A
has
been
provided.
It
contains
the
physical
sector
numbers
of the First sector of each cylinder on each
sUT'fac e.
A
portion of each diskette is reserved for some
special
system tables.
These tables reside
in
the outermost cylinder
of
the
diskette,
cylinder
zero.
Each
table,
with
the
exception
of
the
directory,
occupies a single sector.
The
Tollowing table summarizes the location Or the system tables:
System table
Diskette Identirication Block
Cluster Allocation Table
Lockout Cluster Allocation Table
Director~
Bootblock, MDOS RIB
24.1.1
Diskette IdentiFication Block
PSN
$00
$01
$02
$03-16
$17,18
The Diskette
Identirlcation
Block
is
created
during
system
generation.
It
contains
an
IDJ
the
version and
revision number of the resident operating
system,
the
date
the
diskette was generated, a user name identification area,
and a dynamiC area .Tor the MOOS overlay RIB
addresses.
The
ID
is
displayed
by
the
DIR, FREE,
and
REPAIR
commands.
The
--
Page
24-02
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