EL 00154 00_A_DEC_STD_154_RX01_Volume_Identification_and_Data_Interchange_May77 00 A DEC STD 154 RX01 Volume Identification And Data Interchange May77
EL-00154-00_A_DEC_STD_154_RX01_Volume_Identification_and_Data_Interchange_May77 EL-00154-00_A_DEC_STD_154_RX01_Volume_Identification_and_Data_Interchange_May77
User Manual: EL-00154-00_A_DEC_STD_154_RX01_Volume_Identification_and_Data_Interchange_May77
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Page I
Standard for Floppy Disk
Data Interc'";.nse
(RXOl) Volume
IdentificO!tion
:INDEX:
includes ~erminals, CPU's or any Product which uses
the floppy in its' configuration.
~System
and
i DEC
STD l54
r------
PAGE
NO.
10
11
"
15
"
.l3
"
17
18
19
,20
121
.n
I"
24
125
I"
,27
I"
030
"
131
!32
:33
SEC.
ReV
A
A
A
A
A
A
A
A
A
Page 2
Page 3
Standard for Floppy Disk (RXOl) Volume J:dentification
.. nd Data Interchange
19 May 1977
R. Olson, Author
I This standard defines the data recording
conventions
to
allow
RY.Ol
i~~:~!tt;~ ~:Ch i~~~i~~!~~g :~~~:~ :~il D~~ S~!~~~~: ~iCh w:~il~~t ;~~
reading the volume identification. This volume 1.0. will specify the
origin and format of the data present on the volume.
This standard
appl ies when reading and writing diskettes intended for interchange.
I
All systems wlll oe capable of handling the standard universal
format.
For interchange ASCII is the preferred code for
,volume identification, headers and data.
Bowever, systems
are
permitted to, but are not required to, support EBCDIC in addition to
ASCII. EBCDIC is defined in the Appendix. Other native formats may
exist alld allow interchange.
Iinterchange
l
\
l'Ih~ information is this document is subject to changE!
without notice
iand Should not be construed as a commitment by Digital Equipment
ICorporation.
Oigital Equipment Corporation assumes no responsibility
Ifor any errors that may appear "in this manual.
i
copyright
I
©
1977 by Digital Equipment Corporation
~D~DDmD ~:,':~;'''' "''''''
iDEC STD 154
Page rogram.
Why StandardiZe Now
'1.1.:;'
IE"s
le·.el standards m:.1st b" establIshed to minImIze retrofit in the
nXOl Hardware/Software development e~forts.
Lil{ewise, futUre
:develo>,m"nt an.i support costs C 1:>4
reaj
page 6
~ng
thf' st.anddrd d 15k iden ti t
~cat
Ion.
ThE' mlnimum and "universal interchange" format
will hE'
IBr. IA!-;SI when approved) standard j'l:erehdnge format.
tl1f'
Whlet:
reads ana/o.::
""rites
a
read ilLj/or wrote thE' un,versal
1.3
Scope
1'hl" ~Lar,dard applies to al~ ~onformlng DEC products whiCh s'.lpport the
flop?y d~s.~ as a removable datd rerordlng df'Vlce.
1.
,"1
story
[C'led!:'.f.·
IKI:.\/
~
~D~eD~O
IDEC STD 154
11. 5
Fag .. 7
Related Standards
IIndustryStandardS:
The IBM Diskette for Standard Data InterchangeIBM Pub.
No. GA-21-91S2, date July 1973.
AIDer ~can National Standards Inst i tute - No
ex i st ing
:;tanCiard
for rpcorded file and data interc_,ange.
Standards are belng
proposed by IBM for physical meala specifications
lncluding
physical data
record ing and addressing.
See IBM document
numDer GA21-919Q-~ (file no.
GENL-19), July 1974.
X3. 4-1968 ASCII
a
Proposed DEC Stanaard 167, Volume Topntif,cation for 2ernovable
DiSk Pack DiSk Systems" - Being pxpanded to address "Volume ID
For Director} Devices". The RXOl Volume Identifi.;:ation does
not conform because of compatlbllity with the IBM Intercn;;!.,,:;e
Standard, except for character code.
DEC 051 Standard Codpd Character So:>t (ASCII)
,
'1 6
Future Standards Activities
to be cOrlsidered by thlS
IAreas
Formats Record 1/0, ••• ) are:
11.7
or
rela::ed
the
RX01
and
(e.g.,
other
Data
DEC interchange for til .. s on
direct access devices.
o
Industry standards for d .. ta interchange on dlskettes ano other
removable dlrect access devlcE-s.
rf>mov"ble
Known Incompatlbilities With C"rrent ScftwarC'
I;~~~~~ t ~~;~t ~~~~~~~o~o a~~td~~~e f~rm:~~n~~~d
I"" """'",'.
Isome software Will have to be modified, others
I
standards
a
mD~DDmD'
structure for
Conseguently
to support
Page a
2.0
TERMINOWGY
Locatlon of a sector on the diskette consistlng cf
a
track and sector number (format-nTTOSS", where
T"'frack and S~Sector Number).
A computer character code "tandardixed by AN5
and DEC 051.
X3.4
equivalent term for the character
Space.
NOTE:
Blank. does not mean null Ibit pattern cf 0
in both EBCDIC and ASCII).
An
I>. series C'f
eight
herein
will
specified) .
binary
8
dlgits
(I>.
byte used
bits unless otherwise
I>. complete
ard related group of records (payroll;
accounts receivable, etc.).
Entry)
Data on index track of diskette that ldentlfies a
data SE't recorded on that dlSk by name and
location, and shows
whether or not the data set
has beer: v<"rified.
A flexlble Slngle surface cartrldge disk
enclosed
in a jacket.
A computer character code used by IBM and
for Digital in the ".r>pendlX.
Floppy:
Affectionate na"!)e for a diSkette.
file
Preferred DEC term for Data Set Label.
fast track on the diskette (track 00);
used
datOl set labels, volume 1 Olbel ,
and othp(
softwOlre data.
Process resulting
in
the diskette's
orlginal
physical forr"Olt (see IBM document GA21-9190-1).
I>. bit pattern of
all zeroes.
One or more dOlta fieldS
info:-mation.
(l-12B
interchange records).
section i,n a track on
(1024 bitS).
A
that form
bytes
for
the
disk
for
ol
UJll.t of
universal
a
re~ord
The portion of a movLng storage medium, suer olS a
tape or aLskette,
t'1at is accesGible to G gl\jen
reading
head pos~tion
'26 sectors/track on '"
diskette).
Pa.ge 9
rEC STD 154
A single diskette
Volllme:
* Note: Slzes
hardware.
I
I
13 • 0
1
DEFINITION OF THE STANDARD
~lthOU9h
(physica.Lly is 77 tracks).
speclfied
can
change
with
sOft~are
this standard specifles the
file/data recording and
rocessing conventlons,
there are baSlC hardware and physical I/O
tandards referenced and required in the lowest level of the standard.
~
number of levelS
have
been
specified
to
accomodate
degreE'S
of
~~~~~~~~~g:;e s~~l~le~~a\o~~~~!:~~E" ~~ l~~!~ l:~~ll:~~~~a~~~t~~~v~~~
I baS1S for co:>nformance to other levels - presencly or in the future.
Section 3.1 defines the dIskette standard levels.
Section 3.2
tiescribes the recording components and processing comrentlons required
to meet the specified levels. Sectlon 3.3 indicates possible methods
:for "dherence to this standard and a pro!;>Osed levE'l of adherence.
pection 3.4 includes examples and suggestions for
Implementation of
fhls standard.
t
codes are specified for each level. The charact",r codes for
Olume.
identification. headers and datil mus. t be same. ASCII is the
referred character code and all
system" must
support ASCII.
In
dditlon, systems may also support EBCDIC Ln the Level I "universal
~haracter
~~I~~~ha~J:~ti fi~:t~~~ i~~r ~:;e~n~e~~h~~g~:c~~~:~t in a!~~ s~~~u~~:~ac~~~
tcde.
r
hiS standard address.es itself to the pri.me knuw" FlannPd.llses of
XUl.
Specifically these uses are;
I
.Data Interchange, data entry
.Systems DeVIce, system and '-!ser flles (using natlve
!
.~;~~w~{:t~T:irib"tlon
I
media
All vallles in this standard are
unless otherwise stated.
decimal
Quotation marks when used
in tables.
etc. wbere formats are being discussed,
tdentilY actual data content to
be
recorded.
Page 10
FEC STD 154
fo~ei: ~~: ~~~:el~;~ll:~~l~sf~~m!~~ ~;~k:iie~th!~e1!~~~~~
IfCve:C
(level
iu.ve1 1 is specifIed for wUniversal Interchange" Wilich allows DEC to
PEC
and DEC to other vena or Interchange (I.e., primarily IBM).
ThIS
~evel is called the "Universal Interchange" level.
~eVel
atlv"
2 applies to DEC natIve fil~
tlsage only.
ThIS l,-vel, gillen
Ig~er
level ~ata fIle standards exist, will allow direct DEC to DEC
system fIle/data interchange.
For e"ample wIth
FILES-lIon
pisk data structures RSX-11M and lID will have direct fIle interchange
via the dIskette.
(See level 2 for specifIc details).
See Figure 1
interchange.
for
the
aiskette
standard
levels
and
degree
P"ge 11
Figure I
!
!
"UwIVEHSAL!
INTERCHANGE:"
L2 -------------
!
!
!
BASIC
DEC
FORMAT
Figure I
LJ::VJ::L/DEGREE Of INTERCHANGE
be~ween
systems.
data itself.
Standard
ASCII
(preferred)
or
Allows interchange of diltd to che data.
~'un iv<=r sal Interchange"
Supports all attributes of Level
0 plus:
Ress
only.
J;esefved
Blank
allows
A blank indicates lntended
pOS.
45 Indicates stngle or
blank indicates sinqle volume.
and "L" spe<':lfics the lazt volume 1n a
46-47 Multi volume seguence identlfiers
pas.
75-79 End of Data (EOD).
the next unused sectOf.
5.
slock/R",cord length is flXed
Indtcates the address
(can be between 1-128 bytes)
Support DEC and ANSI ASCII code fOf headers and data.
In aODIX A dnd B.
Track
00
is the
~Jn9~?'·r"tr,~fk" which contatnS thlS basic
the
EBCDIC
Null
iCEe 'TO 154
Page 14
10 and directory data.
IDEe
Volume 10 3.nd Nat.ive Formats
:
Support all attributes of Level 0 plus
=
1.
DEC standard 11;7, Volume Identification for Removable
Pack Disk Syst.ems (See Section 1.5 of this standard).
2.
Accomodate a sector interlace of 2:1
(i.e., Read or Write
every other sector in a single block 10 transfer). The track
to track offset. (skew) is Six (6) sectors. Virtual Block 7
(in appendix C) is mapped with the 2:1 interlace and b sector
track to track offset..
{See APPENDIX C for the specific
Disk
mappJ.ngJ.
3.
Virtual block$ a::e 512 bytes in length (4 physical sectors)
Support s<:-~lldard DEC ASCII characters in volume 10,
header, alOd data.
EBCDIC is not permitted in level 2.
5.
file
Documentation defining approved -Native DEC~ file formats for
use on the Floppy Disk is identified in appendix -En of this
standard. Any "Native nEC" file format to be supported on
the floppy dlSk mu.st be registered with the Standards
Committee so that it can be ECO'd
into appendix "E-.
Registration is initiated by presenting the proposed native
file format to the Standuds Administrator and re{,juesting
it
be put on the Standards Committee's agenda for approval to be
made a part of appendix "E".
Attendance at the Standards
meeting which will ad'lress this agenda item may be required.
It is strongly recommended that prior to defining a
new native
format,
the ones identL::ied in appendix -E" be evaluated for
use rather than creating a new one. This evaluation should
take place early in the product development phase so that the
product won't be impacted in later stages by file format
issues.
The StandardS Committee is not likely to approve a
new native format until all existing ones hllve been evaluated
for possible use.
r,
2
Recording And Processing Specifications
is section gives a precise statement of what happens during
rl_DmD!fD::~~~"9Rn'T.,,r;lli-pg
initial i2atlOn, Volume ID, data
the
,PEC
STD 154
Page 15
~irectO[Y
"cc~ss,
ban~ling a~(!
operations, data
error
devi.ce handling.
he actual
recording
speciflcations at:" tdentifled throughout this
Sect10n and the Append1ces.
Tbe
processIng
of "levels"
will be
properly differentiated ..nere 'lecessary.
?2.1
Physical/LogIcal Layout
~he physIcal organization is the standard IBM
format.
APPENDIX D shows the complete layout.
Interchange
~he 10gLcal layout varies dspe"ding on pr1mary uSe {i.e.,
Diskette
Interchange
1's native Systems Device) .
!JNlVERSAL INTSRCRANGE:
;r'he overall
,",PPJ::NDIX A.
laY0:.Jt
"univer sal
interchange"
1S
described
il'l
SYSTEM/NATIVE:
:r'he RXOI
flIe svstem
natn'e files device "'ill be
functionally the
wbich it res1des.
A Dt.C "UniveLsal" file
standard.
fO,.OC"i>
I
F.2.2
volume InItialization des must be "PRINTABLE ft ASCII cod.:.s {i.e.,
they must
use characters in the 41-135 ectal value range after stripping bit 8,
the left most (bigh order) bit).
Every system m:lst be able to read "nd process the hasic
four
byte
Volume
ID.
The minimum req:lirement is to print out lhis rD.
I t is
required for systems with mO'lnt or similar commands to
also
indicate
their ability to process the volume and .;;ontinue automati<;:ally if the
t~~~me v!~:.~~cel~:~~~fic~~~;~t :~:~1 t~~e t~la~~e w~~~~~~or ~~y ~~~~~~~;
information or assistance. The Volume ID function should be performed
l'Iutomalically as a part of the rnour.t function.
figure 2 depicts the speciflC values and
level of support for
Universal
Interchange.
The purpose ar,d steps for initialization are
fls follows:
PiSk Initialization
hll diSKS are initialized before they are shipped to a customer.
F-einitializing should bf' avoided if possible;
i t is required only if:
A sector sequence other than the sequence existing on the
disk
LS
desired.
See figure
2 ~n
th,S section for
~nformation on how to specify the desired sector sequence.
~D~DDmD··
IDse STD 154
Page 17
r---------------------------------------------to reinitial ize when
be>
re-used fot new
;The purpose of initializ"Ition
1.
~s,
To write a
,,,"cord in c:'!ch sector of each active
tr"ck.
All
records are filled with the blank character (EBCDIC) except
in track 00.
In the future, if DEC provides hardware
to perform HlitLlliz"tion, Nulls rather
than spaces will be written.
This is
because most of O'.lr character oriented
harcll"are and softwa.re strip out nulls.
To write SO-character Volume ana file ne,Hler records in track 00.
After the index track is written, sectors 1
blar.ks each.
Sector
S positions 1-5
followed by 7S blank characters.
If
on" or
~,>pccified,
the numbECr of the first b~d t.rack
:and 8 of sector S with a zero in position 9, th'"
,"Old track will
be in positions 11 Clnd 12 of
position l:l*.
L_____________ _
" Llmited lor no suppC'rt.
Support on read anI:,.
(See Figure 2 below).
Pag-"
L8
Sector 7 contains
i'1 pORit~ons 1 through 4, thE'
vcllL"'"
ID in
positions
5
tht"ough
10, ttle sector sequence code is in positions 71
and 78, a "101" in position 80, and bl~nks in all remaining positions of
the first 80.
Sector 8 contains the following do.ta set label:
"HDRl"
is positions 1-4
"DATA~
in positions 6-9
"80"
in positions 25-27
"01001" in positions 2'<-13
"73026" in positions 35-39
~OlOOl"
in positio"s 75-79
bl,mks in all other positions
Sectors 9 through 26 contain deleted File header recores {See
3.2.5 for "xplanat;,~n} with the following content,
"DDRl"
in positions 1-4
~cctcr
number
~80"
Sec~ion
in positions 10-11
in positions 25-27
"74lJOl" in positions 29-33
"73026"
in positions 35-39
"740[))"
in positions 75-79
Blanks in all other positions
As <> final step. disk i.nitializatior. c~,ec"s ttl" d~sk to see that it is
Iwr i tten correctly.
PEC STD 154
I
Page 19
Figure 2
,, .
(60 blanks)
(
)
)
)
positions 1-5 '" ERMAI'
positions 7 and 8 '" First bad track
positwns II and 12 '" Second bad track
positions 9 and 13 contain zeroes
(Remaining positions ilre blank)
All positions except 1-5 will be
blank if there are no bad trackS.
Reserved
(80 blanLs)
Volume Label:
positions 1-4 '" VOLl in EBCDIC Or ASC-=I
(for
Universal Interchange). or other authorized
4 byte codes (ASCl' only) which uniquely
identify the format of this diskette (e.g.
"RTll" for RTll system disk format)
positions 5-10 specifies the ID of
this specific volume.
Comes from IBM
when new as 'IBMIRD".
If reinitialized i t wi:<1 either be blanked or
will contain a user specified 10.
position 11 '" ·'Accessibility".
Blank
indicates ava;lable for processing.
Any non-blank character means disk
is not accessible.
positions 36-51 '" owner 10.
positions 77-7~ = "Sector Seque"lce
"::ode" .
01 - A one to on .. interlace (i.e.
sectors are processed 1. 2. 3 •.
25.26)
02 - A two to one interlace (i.e.
Fectors are processed 1. 3. 5 ..•
23. 25. 2, 4 .•. 14.26)
77 - DEC 11 Interlace.
A two to one interlace with a 6
sector track to track offset.
Actual layout alld specification
is in Appendix C.
oor:;ition 60 - "W" The "W" stanos for
. standard label processing. This
fielo must be own fcyr Interchange
,,11 other positior:s in the Volume
Label are blank
DEC STD 154
~vel
Page 20
po;ition 1-4 - "HDRl~ or "DDRln. Sector
8 lS initialize''] to "HDRl w and 9-26
to "DDRl", "DDRI" indicates a nOnexistent or del".ted data set, tecause
of the "D" 1n 2osition 1 of the SE'ctor.
2 -
DIgital Native
biskettes InitIalized tor "native" system flle us", n",ed not
all
the
initializati'Jn
specifications of level 1.
~~~~ir~:~~;r i~h~~ ~~:tE~g;I~e~~!r~c;~;u~~d;~
specifIcation
Directory OperatIons/Data Set "aoels
bata Set Labels (DSL) must be processed according to the the recording
~~~~~~t~:t5~~~ s~! L:~~~S. level and APPENDIX B.
Level
0 does not
~vel
1 -
DNIVERSAL INTEHCHANGE
Section 3.1 (levels)
Indicates what DSL functlons are supp<)rted.
ertain features such as creatlon and expiratIon dates are not
u?ported. The uSer must b" capa0le of creating, modIfying
and
fm;n::~:~:c:O:e~":;;:;,;~;o~:"~:::";e< (;~:~"
~~:r~;;;iL op~::~~
lelds 1n a Data Set Label (e.g.
End of Data
during data access processing.
Othf'rs are
flle (e.g. BOE, and EOE, data set naJ>le, and so
De updated
,,[eatlon of a
and
block level
Slze have been
trhe intent of level 2 is to iden'cify a minimum (one 15 1deal)
set oi
DIGITAL native ftle formats for structured nati.ve £lIe system usage of
the Diskette wtth the broadest degree of DEC to DEC in':erchange.
~.2.~
I
l :ve~y
Data Recording/Access
,"codoco 0"'/0' '"CO
system Shall read and wrlt.e evcr} bit in every sect:!r
,e::: :"h"O
""oo,",e oe,omed.
~
:eadjWrite support of fIXed l"'ngth records from 1-128 bytes wlil be
'ro~DdmDDmDl,~,l.mum support 113 sequential access.
The dat~ :ec'nds arE'
!DEC STD 154
Rfiy
A
Page 21
IlunblOCked with no centrol information (exc:e>pt
possibly
format
effectors alld for error processing. See next Section - 3.2.5).
Irecording mode for IBM interchange, VOL 10 = "VOLlis EBCDIC.
Inormal file access functions apply.
,Level 2
'Data Access is specifled under each level in the DEC native
specifications (see Appendix EJ
I
recording
,
:3.2.5
Error Mapping and Processing
[Levell
IThe ERMAP processing as defined in the "Universal Interchange"
format
limplies both software and/or hardware support.
If hardware can
i1nit1al1:/:e addresses it shOUld completely skip a given bad track and
!reassign addresses to the next tICack in sequence toward the center of
the disk.
'.rhe hardware should fill the track with bad track codes.
j(Present RXOI hardware does not support the above).
iThe sottware must set the addresses} of either one or two
,in the proper
positions
exists for readdressing.
of
sector
!If more than two bad tracks exist,
the
:existing good data) should be discarded.
bad tracks
5, track 0 if hardware support
diskette
(after
recovering
;All conforming DEC systems supporting Level 1 or a':love of this
standard must at least recognize the ERHAP information on READ OInd
indl.cate support or non-support.
If there arE' bad tracks
marked and
the system does not handle them, this :TIust be so indicated. WRITE
support need not be provided
(write support requires
hardware
support).
!l'hc NDEI.ETED DATA- (DO) mark is used in level 1 as buth a deleted
iPhysical data indicator and as logical data delete.
If the deleted
kiata mark is set then the first byte of the
128 byte sector
is
linterpreted as follows 1
Value
(ASCII or EBCDIC)
Meaning
the record has been
log ically deleted.
As an example, t'le 1ata
set labels in sectors 9-12
of sector 0 contain a ~D- in
position 1 when the floppy is
initialized and files do not
yet exist.
indicates a surface
defect and the record
REy
IDEC STD 154
I
Page r
",hich ",as to have been
wr itten here ",as dia~
~!~~~~. to the nE'xt sequential
I
13 . 3
All systems must supper t Level o.
~s a minimum all conforming systems whwh ",ill use
i,nterchange must support this standard at level:.
the floppy for
Level 0 applies,
~~~n eX:~le ~ ~~t~~:n~~~!o~;s~;:g~~!t~~ ~~!t;~~~p~ m~~~ s~~=~~~sle::~c~
Irf1~he f~~:~~:rd t~it~:r ~!~~C~~J t~~ ~~~p;y f!;~t t~:n~;~~~t~~~r~th t~!~
fStandard.
Specific support levels and dates for
support are a subject for
another document.
It
is recom'!lended that all conforming systems
.support levell, at least wlth ASCII ",ith duect I/O.
Exceptions can
~e
made, but must be approved by tne Software Standarols committee to
~llow conformaEce via such mechanlsms as a
"file conversion"
or to
rllOw deviation from the standard as such.
,
I
!3.4
EXAMPLES,
SUGGESTIONS
~vice handlers should themselves ~e designed to accomodate varying
sector sequences.
Once thlS is accomplIshed, the direct support of
'the floppy 1n either "UnIversal Interchange" or nNative"
formats can
~e handled VIa a higher level file support function.
C~~l at~~ch~~e aPi:~d !~:~ 1~~~a~~~~~e~~e~he l~j41 S~~~d~~~~ g ~~~u~~~i~~le~~
E>>:amples of usage, functional descrIptions, and so On of the diskette.
1'\.150 useful background
information are the DIGITAL speCIilcations
(Engineer1ng spec.
for th., RXOl, 1'11357 RX8E OMnibus
interface, and
'Xl! 'oibo" iO,",Coool.
r78"
i
I
p3Qe
EBCDIC and ASCII
Conversion Tables
n
Page
ASCII
CHARACTER
"L
,00
STX
'TX
om
ONO
AC'
''"
"'T
"
CR
"
"
VT
50
OL'
DCl
DC2
DCl
EBCDIC
CODE CODE
000
00>
002
0"'
00'
005
006
007
000
001
0:)2
COl
067
055
056
m
010
Oll
012
013
01.
015
016
026
COS
04'>
OIl
Ol<
01,>
016
on
'"
020
021
021
022
C23
022
023
DC.
02.
07<1
NA'
025
026
075
062
046
~1[)
010
eM
03.
OJI
'00
032
077
ESC
C5
05
""
R,
OJ6
0'
,
047
03<
m
035
015
016
017
SPACE 0.0
0<1
0<2
100
In
177
DO
1'3
044
0<5
0.6
040
IS.
120
m
llS
135
10.
116
'",
051
OS>
051
OS.
~D~DD~
,/:i.;i.~.
153
,
,1.~O
"
PagE'
056
05'
113
141
060
061
062
063
06.
360
060,
066
061
365
366
W
no
072
073
07.
075
076
077
371
In
136
114
176
156
157
100
101
17.
301
".
'"
",
103
105
106
107
110
lU
112
113
11.
302
303
305
306
307
310
3U
321
m
023
115
m
H6
325
326
117
120
W
122
123
124
'"
126
'"
130
131
132
133
134
J
'"
070
on
~IDmDDmlH
361
"2
363
.
135
.,~
327
DO
331
3"
343
344
345
346
W
350
351
112
340
132
l,"
25
fCC
Page
STD 154
l-
"
i
140
17l
201
Hl
'"
143
'"H5
He
203
'"
'"
205
2"
207
141
210
150
151
152
153
15'
155
15£
211
221
m
m
225
'"
'"
'"
'"
157
160
161
102
163
16.
23G
231
W
'"
"5
165
166
246
no
250
'"
171
m
251
m
m
300
152
320
W
007
175
176
177
Conversions from EBCDIC to ASCII which are not defined
should
result
Control Z.
",hi<;h
in
the
ASCII
Substitute
See ANSI x3.4 and DEC
use Control
Slant (134)
051
(S[JB~032).
standards.
z to mf'an End of File, should
1.1':.,
Systems
use Reverse
inoltead of SUB.
The above conversions. \Jere obtained
Hollerith Plmched Card Code.
From
ANSI
X3.26-1970,
(Tahi.= dl in Appendix B).
Page
FEC STD 154
UNIVERSAL INTERCHANGE
DISK LAYOUT AND INDEX TRACK/
IBM PUBLICATION No. GIl.21-9182, dated- July 197.1
27
Page 28
!DEC STD 154
Flsk Layout and Addressing
iPerhaps the easies~ way to descrl~e the layout of the d,-skette disk 15
!lea camp"re It with Items famllar
to you - phonogr"ph records and
record players.
'First, assume
shaped like a
that you have
placed a magnetic-coated disk that
is
r ecerd onto your record pI ayor. Then, assumE'
record player:
Instead of the tone arm (the arm holding the needle)
moving
freely as the disk: turns, the arm remains motionless at any
spot to which it has been moved.
You have dev iEed a way to mve the arm to anyone of
77
possible locations along the radltl5 of thf> disk (that is,
along a line extending from the outer edge of the disk to t!l~
center
of the dlSk)
and have ntlmb .. rea these locations
consecutlvely from 0, starting at the outer edge of the disk.
YOlJ have replaced tne needle usually held by the tone arm wlth
a read/Vlrite head Similar to the One llsed on tape recorders.
The deV1C'" you would have bUilt would be slmile~ 1n principle to
device used to read and write data O;lto the disk in a dlskette.
tne
Conslder what wOlJld happen as the disk on your record player turned.
At each locatlon, a band the width of the read/write hc.ad would pass
under the head, forming a circular band (track) when the disk had made
pne cOffi>llete revolution. These tracks would be concentric, and c,?lJld
be identlfied by the same numbers assigned to each arm locatlon.
trherefore, moving the arm to location 0 would always place the
lead/write head over track 00, moving the arm to posltlon 5 would
filways
III ace the head over track 05, and so On. The disk wOu-Id have
been divlded effectively lnto 77 S2parate tracks that "'2 could
~dentify
by number ar;d to whlch we could mOV2 the head W:lenever we
(:leslred.
Data could be recorded onto or read from
the track as it
passed under the head.
iDEe STD 154
Page 29
~---------------------------------------------
I
The disk slJrface is divided into 26 equal equal-size wedges.
The wedges are each assigned a dIfferent
t;~roLlg~ 26, and are called sectors.
nllmDer,
from
01
nLmbering always starts with "ector nurnber 01.
r"rom I to 128 characters can he stored in each sector.
f' Sf>ctor is called a record.
Data stored in
To locate information, the machine locates the
is, the tt"ack and sector number.
address,
record
1I.lthotlgh the disk has 71 tracks, the IBM 3741. 3742.
3747, and
cannot uSe more than 74 tracks at a time.
Two of the tracks
jY ~1I!I1~Dt.~.e",~,~~k",,~~~,.be,ing reinlti"J.ued by the 3741 or
"-hat
J,'age
30
POlge 31
178 Sv,e, D... f,,'d
\
TO , •• dor
w<".
J
'nf,,,m~',,,,,.
, ....
on. IA~"" (·fdoto" ulUoI'v M!"ol
'o.,mlli."" ... d'1lJt.o',~'.'<~"oc'"
b".~.".""". com .... , .te l
... ,g
f,e'd :mot ,'_ ,n. t>-;t., bo'_en AM2 ", A~3 ."d
Ihe "..
'j "'d'Md."f"'d
~~:c~·;.::;;,:O:~::·t~::::::C:,:~·CL
fu, ,u'''''''''" ."0' 'h.""'~~
'.d<\"";n ....
'~~';',~~.~::;::::.f:~~d. "t~:'~·~:'n~.~~
::::m,
IDEC STO 154
Page 32
f
IINDEX TRACK (TRACK (0)
lAND INITIAL CONTENT
i
th~5
LABEL INFORMATION
~n
lese
chart
conj":lllction with the reference manual foe the device
lor devlces lJSlng t_h"_"_'_'""_U_"_"_ _ _ _ _ _ _ _ _ _
==::--,
~~~g~:~~~~~~~~~:::~~~::,:~,:~''''
. ,"
;~~~2:~:.:·:~~~~~~~"~·:~:":::=·, ..
1 • - ~
."'
__ """0"'.... ",,,",_ ..... _ot, ...... <...., " _..
'oe"",,,'3 _0,' 'W""" ""'," _ _ , ",,0""". "t",,- 0,"",,0" ,3,0''''"'' ~"" •
•"',',"".'4.,"0..... n_" ......
• ""',"".3~ .... r,,''' ......'''"''...... <"~ .... _,,.''''.....oo,ob "J~o ... n.'9'"
•
::::',::;~~ .:,:::'t~::,':.:vO,::.~"
.",,".. ,,0".' .... 0"'"••••"0'."._"'""
...,,'."".r .... J_ "".,:1,' "'''.<0 .. ""." ,,,.
~ ~::::::::~:,:::,:::;::~.:::;,:::,~,::,;:::::::,~~::::;:,::,:::;:.
o<." .... ..,.........."
T" .• '.• ldO""~·'0.","'.""'.""'u.,.'D'.OId
"..-....,"" .....,'.,01'01'0"..'''",........".
Tho
10"""... ""'00.1<> ".""......,
:,':,:::::: "'':'"....;~::'"5''''' :.'..:.:.:t:::·:;::::.:.t"::.;:: .:' ;:::;;..,
..
.
;::'~:::':~~;~:~~~~~~::-'ho''''''' (~ "l ~ ~ •.,•• _",_
.....,.".-.,~."'''.]."'''.'',.' ....''"'''O<_.'.'''...,.
MV ............ <"".."., ," ,".. ,..,...... ",'...""....... ".'...-~b'.a',,..
.....",,'OO _ _ ....
m . . ".",""
.... ' •.",,11 3' ....... ' .. ·•
P""".,,18 s, ....,"""'"....... ' ,or,.'.
.,'''''0.,5216 ....... '.. '0
Th" , •• '. " "",'''''''''''.,,''''''''''
I--+-----=:;;~~j~:~~~~i.:~;~~~;;~~;~;;~:~~,~~:~~::":" I"."
..:.-
~""
.. _'''' .... "".'0 ""'0 ,". "" ..' ,_"
' ... , .........."
,.~
".1.,", '"''''''''~'
"".... 4"""... 'OI.," ...... n"'·"'d'"'''' 1.Soo1lo1.S.':"O..... U.""'."dl",' .. ,C~M.""
~II~IIII~II
DHA"8.'
s..
.,.,.$0, L-'
Page 33
"UNIVERSAL INTERCHANGE"
IBM PUblication No. Gil.21-9182, dated- July 1973
Page 34
._",0".""",," R",,,,,,,,·on.' D". Dn,'.
,_.'m ..... A"." ... S"",",o,,,.,,",,,08,..
• .. , . . . " , " .. "N_D, ......
C . . , .....
"",,,',.'d<,,",.,",,e.,,.,,,,,,",obo,..do"'.
::":,~;,"~ ..,, . . . b " .
'".,"w,.,,," co.,".'',
IINITIALIZATION OF ID FIE:LDS ON NEW DISKETTES
~tSkettes
spctors
:sequence
IB~l
with the identification
Sectors are numbered in
sector 01 thrOllgh track 76,
,~~"'.,.
Page 35
IDEC STD 154
(SAMPLE VIRTUAL aLOCK TO PHYSICAL SECTOR MAPPING)
VIRTUAL
BLOCK f
TRACK
I
01001
01009
01017
01025
01008
01016
01024
02011
02019
02001
02010
02018
02026
1'1' = Two digit track
AND
01011
01019
01002
01010
01018
01026
02013
02021
02003
02012
02020
02002
* (00-76)
55 = Two digit sector t
(01-26)
SECTOR NUMBER
(TTOSS) •
01007
01015
01023
01006
01014
01022
02009
02017
02025
02008
02016
02024
02006
01013
01021
01004
01012
01020
02007
02015
02023
02005
02014
02022
02004
(10)
bytes
SECTOR" 128 (10)
BLOCK" 512
bytes
IDEC STD 154
Page 36
TRACK OFFSET
(used by OS/B)
(SAMPLE VIRTUAL BLOCK TO PHYSICAL SECTOR MAPPING)
TRACK AND S£CTOK NUMBER
,
7
,e
"
T'!:
01001
01009
01017
01025
01008
01016
01024
02005
02013
02021
02004
02012
02020
= TwO digit track
01003
01011
01019
01002
01018
01026
02007
02015
02023
02006
0201 ~
02022
* (00-76)
55 = Two digit sector 'if
(01-20)
(TTOSS)
*
01005
01013
01021
01004
01012
01020
02001
02009
CZ017
02025
02008
02016
02024
BLOCK =
5L'. (10) bytes
SECTOR" 123(10)
bytes
--""'""'g,'--'-',,_
:DEC STD 154 _ _ _ _ _---'":.:'-.-"-_ _ _ _ _ _ _ _
DEC 3:1 INTER[J>.CE
(COS 310)
(SAMPLE VIRTUAL BLOCK TO PHY3lCAL SECTOR MAPPING)
VIRTUAL
BLOCK t
01004
01013
01022
01005
01014
01023
01006
01015
01024
02007
01001
01010
01019
010('2
01011
01020
01003
01012
01021
02004
COS
01007
01016
01025
01008
,n017
vl026
01009
01018
02001
02010
310 3:1 interlace without any offset appears above.
Three (3)
form one block.
The mapP;·TIg of PDP-iI, 12 bit words to the
8 bit sector bytes is as follows:
A block is 256,
12 bit
wo~'c".
The fust 4 bits (left or L1Fpermost) arf' stripped
[rom each
of the
256 words (lnd packed in 128, Z bit bytes (i.e., the
first sector out of three which will contain a block).
3.
The remaining lower B bits of each word are
next two sectors USing the J,l interlace.
written
From the above exan.ple, block 1 is mapped as follows:
Upper 4 bits of 2~6 words are in
bits "n.' packed (IS follows:
sector
01001.
,
: <-----byte 1 of sector
(OlOOl)
P"ge
36
from
word 1
The lower 6 bits of the first 12B
words
arE>
in
sector
(01004) .
3.
5.
The lower B bits of the last 128 words
in sector (01007).
There is no trac~ offset.
sector 01 of each track.
~D~DDmD ~:., ,..,
A
b1oc~
will
(:;>'..It
of
always
256)
begin
are
at
IGEe STD_'_"__________________________________p_'9_"_3_'__
!
*BON - ftBeginning of Native" Digital file system space on a
Diskette will norI:lally contain the primary (initial
boot when used ,,,, a "systems device".
PDP 8/11 Systems
boot from sector 1, track 1.
Page 40
'*Each developer must
insure
'form
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