IBM 3340 User manual

GA26-1619-4
FileNo.5370-07
Reference
Manualfor
Systems IBM 3340/3344
DiskStorage
IEnfi

PREFACE,
Thispublicatic,n
isintended
to familiarizerCata proc-
essing
personnel
lvith thecharacteristics
ol'IBM
3340/3344 Disk Storage.The reader
should
have
prior knowledge
of direct-access
storage
dievices
and
concepts.
This publication
isorganized
by topics
asfollows:
r INTRODTiCTION - Describes
basicunirs
and
lists
highlights
andf'unctions.
o CONFIGTJRATIONS
andATTACHVIENTS -
Definessorne
possi'trle
combinations
andsvstem
attachmentsfor the3340i3344.
o FEAT'URF,S
- Describes
both standand
and
optionalfe:rtures
availablefor the 334(l/3344 with
illustrations
of some
combinations.
o FORMATS - Describes
andillustrates
thc record
andtrackIrtrnrats
for data. Also provided
are
Record,iT'rack
capacity
chartsincluding
formulas
for capacitll
calculations
of various length
records.
o INPUT/OLTTPUT
- Includes
addressing
methods.
accesstintes.
andidentifies
security
and
privacy
me:ans.
Listsand
summarizes
the
3340/3341 commandset
andsense
byte formats.
Alsoincludes
an
errorcondition
tableandthe
associated
{lrrorrecovery
actions.
o OPERAI lNG INSTRUCTIONS - Describes
all
switchesanrd
indicators
associatedwith tht:
Fifth Edition
(July1975)
'Ihis pubf
ication rcplaces
arrdnrakcs Re.l'erence
Manuul {r:r lBll[ -t-]40 Disi
Storase,
Ordcr \,r. GA26-1619-1.
obsolctc.
Significant
chattg,:strr
addilions
to thcspecifications
containcdin this
nubliearrgn
arecontinuallyhc-ing
ntade. Bcforc usttrg
ihis grubliczrtion
irr
corrnection
with the
operation
of IBM equiprnent,
c()ntactthe
loc:rlIBM Branch
()flice for rcvisions.
copies of thisarrd
other [81\1
publications
can
beobtained
thr<iush
ll]fulllranclr
C)ffices.
.Aform for readcr's
rommcllts is
provi<1ed
at thc backof lliis
nublicalion, lf thr:
fornr has
beenrentovcd.
send
vour c()ntinent:, to theadclress
h,:low.
'fhis nranual
was
prepared
by thc IBM Gc'cral Pr'duc1s
[)ivision.
Craphicsand
Publishing.
Departmcnt G26. San
.,Iose.Claiifornia95
193.
!:'
Copyright lnternational
Ilusincss
Machines
Corporation lg7
j. 1974,1975.
3340/3344 OperatorandPowerPanels.Provides
suggested
instructionsfor datamodule
unloading
andloading
proceduresandthe EnableT'Disable
Read
Only Function.
The following publications
arerecommended
for
detailedinformation concerningthesubjectscovered
in thismanual:
c IBM System/370 Principles of Operatlon, Order
No.GA22-7000.
c IBM 3348 Data Module Handling Procedures,
OrderNo.
GA26-1625.
o IBM ,1
340 Disk Storage Fixed Head Feature
Users
Guide.OrderNo. GA26-1632.
c IBM Reference Manual for Integrated Storage
Contol. OrderNo.GA26-1620.
o IBM Reference
Manual .f-or3830 Model 2
StorageControl,
Order
No. GA26-1617.
o The Data ProcessingGlossary,Order No. GC20-
|
699,definestermsrelated
to direct-access
storage
devices.
o Thc functionalcharacteristicsmanual
applicableto
thc parent
system. C)rcler numbersfor functional
characteristicsmanuals
canbefound in the IBM
.S.y.stem/
360 and System/370 Bihliography,
Order
No. GA22-6822.
ii IBM 334014'1
Re
ferencc
Manual

Introduction
IBM 3:140 Disk
Storage
DataModule....
Defect Skipping
IBM 3344-82ll]2F Disk Storage . . . .
IBM 3340/3344Units
3340/3344 StorageClontrolandFeatures
StorageControl Devices
Special
Features
StringSwitch....
RotationalPosition
Sensing
FixedHeirds
Configurrations....
3340 Stc,rage
Without 3344 .
Modeli
I l5 (115
DDA)
Modet1'25
(125
DDA)
ModeL
13-5
(IFA)
Moclels
135.145.155-ll,158,165-ll,
ancl
l68 (3830-2) Models145,l5B.
ancl
168
(lSC)
3340/3344 Configurations . . .
Modell.15
(IFA)
Models
135,
145,155-tl.158,165-ll.
anrl
168
(3830-2)
Models145,158,
and
168
(lSC)
IBM 33418DataModule . . . .
Data Mc,dule
Types
DataMo'duh
Initialization.. .
Data
Surfacc
Format
Formats
RecordFormat
Count Area
Key Area
Data Area
TrackFormat....
Home Acldress
Track DescriptorRecord(R0)
DalaRecords....
'frack Capacity
Input/Output Operations
DeviceSelection
andAddressing. . .
DeviceAddress
SeekAdclress
...
Access
andDataT'ransferSpeed .
Pagc
ol (iA26-1619-,1
Rcviscd
May 16.
lt)76
By'l NL: (;N26-012ti
CONTENTS
Access
Motion Time .
HeadSelection
Time
RotationalDelay .
Data'l'ransfer l1
DataSecurityandPrivacy . . 11
ReadOnly Function 11
FileProtection... 11
Seek
Verification. 11
ErrorRecoveryProcedure..". 18
ErrorCorrection Function. . . 18
ErrorCondition
Table ltJ
ErrorRecoveryAction l8
Constructionof
RestartCCWs ....... l8
ChannelCommands
SenseCommancls
.
Control Commands
Rcad
Commands
.
Write Commands .
Search
Commands
Sense
Data
Sense
Byte
Suntmary
ScnseBytesO-7Suntmary..., -15
3340Sense
ByteFormat I Summary l(r
3344 SenseByte Fornrat I Summary -lti
Formats
l, 4,and5 MessageSummary 40
Sense
ByteFormat
4 Summary 1l
Sense
Byte Format 5 Summary 4)
Sense
Byte Format 6 Summary '+-3
OperatingInstructions
3340Operator
Panel
3344
Operator
Panel
3340/3344PowerPanel .
Machines
Without String
SwitchFeature
Machines
With Strins
Switch
Feature
DataModule Loading
Data Module Unloading 4()
ReadOnly Function '+7
Enable
ReadOnly F-unction 1'1
Disable
ReadOnly Function 1l
Index. 48
t6
l6
t1
3
3
3
3
3
3
4
4
A
4
4
l.)
i-)
_-)
J)
-:)
i)
l4
j'1
4
.4
4
,+4
44
14
4l
4-\
46
6
6
6
6
8
8
6
d
8
8
d
8
8
9
lo
l6
l6
IO
16
Conte
nts iti

['a-ec
t'l C,'\]ri- l(r
l9-.1
Rt'viscd
\1ay
2(r.
l9
/(,
tsy'l
Nt-: (;\16-().1:tt
FIGURES
Figurel.
Figure
2.
Figure
3.
Figurc4.
Figure
5.
l'igure b.
Figure
7.
Figurc
8.
Figurc
9.
Figure10.
IrigureI I.
Figure12.
Ittlvl
3340/:1,144
Disk
Storaire...
IFA
3340/-i344
Maximunr
Cenl'isuralion
ISCor
3IJ30-2
Maximurn
Llonl"isuration
l)ata
Surface'l'rack
l-ay,out
. . . . .
l)ata
Module
(ieonrctrv
l{ecord
and'l'rack
Formar
l'rack,/(lyiinclcr
C:.ipacitir:s
- No Kcls .
Darta
Module
Capacitics
- Ntr
Keys . . . .
-l-rack,/Cylincle
r Capracrtrcs
, Wirh Kcys
Datafr4oduie
Capaciticr
, V'1irh
KL:y's
Errclr
C<inclitiorrfehlc
Rccovery
Actiorr
'l
ablc.
lic:nseLurnrnand\
(
lontrol
(.
onrnrirrrils
Rcaci
(-ornnrarrds
Writ.e
(.'ornmanLls
Search
(.'ornnrarrrls
Scrrsc
[3yt.es
(.]- J Sumnrary . . . . . .
-J-1.10
l'orrlrat
i 5c;tsc
llttc Suniltrarv . . . . . .
-l.l-1.1
l orrrurl
I Scn:;c Bytc Sunrutary"
. - .
lrormats l. 4, and 5 Messap'.q'
Surnirr.rrv
Fornt.rt
-l
Sulrrnrrry
I olmut -5 Surt)nliir)
Frrfilli-rl
6 Sutilnlltrv
Opcrator Panc:i,ll-140ancl
3j"l4 "
Powcr l)arrel,
334f)
/ 3341
ljata Module [.oad,'Linlrred
llttrtl
()lriv
l,rr(
ll.tl
5
)
l(r
)l
-19
-)l
ll
,15
36
-18
10
4l
.1
,l
-tr.1
:i4
,16
,47
it llJ\l .i.lJU,.++
Rclu,rr.tr.t'Iilrrru:rl

TheIBM 3340 DiskStorage
provides
direct-
accessstorage
for IBM System/370
ModelsI 15,125,
135,145,
155-II,
158,
165-II,
and168.
The3340
consists
of aModel
42, control with dual-drive
disk
storage,
andup to three
attached
dual
(B2) or single
(Bl) driveunits. The 3344large-capacity,
dual-drive
unit can
besubstituted
for the 3340 B-type
units
onIBMSystem/370
Models
135,
145,155-ll,
158.
165-II,
and168.
The3340/3344isamodular,
high-speed,
large-
capacitydisk
storage
subsystem
for database,
data
communication,
or generalpurpose
use.
IBM 3340DISK STORAGE
TheIBM 3340direct-access
storage
introduces
two
technological
advances:
adatamodule
and
defect
skipping.
DataModule
Thesealeddatamodule
cartridge
contains
storage
disks,
drivespindle,read
andwriteheads,
andaccess
arms.Thedatamodule
has
severaladvantages
overa
disk
pack:
o Thedrive
datastorage
capacity
canbechanged
by
usingadifferent
datamodule.
o Theheads,storage
disks,
anddrive
spindleare
sealedinside
thedata
module.Thisavoids
contam-
inationfromoutside
sources
andreduces
preven-
tivemaintenance.
o Reliability
isimproved as
eachhead
reads
onlythe
data
thatit previously
wrote.
Defect Skipping
Defect
skippingallows
datato bestoredbothaheadof
andfollowing
asurface
defect.All of therecording
trackcan
beusedexcept
for minute
portions.Since
theheadsnolonger
needbemoved
to analternate
track,accesstime
issaved.
Datamodule
capacityisnotchanged
by defect
skip-
ping
and
t.heuserisrinawareof defects.
INTRODUCTION
IBM3344-B2IB2FDISKSTORAGE
The
IBM3344-BZlB2F
dual-driveunit provides
increased
capacity,lower-cost-per-byte,
direct
access
storage.
Each
3344
drivestoresfourtimesthe
quantity
of dataof a7O-megabyte
data
module
by
usingfixed
media.The3344dual
drives
can
replace
the
3340
B-drivesina 3340
stringonIBMSystem/
370Models
135,145,155-II,158,165-II,
and
168.
The
3344-B2F
containsfixed
head
storage.
Defectskipping,
similiarto that
used
onthe3340,
isalso
used
bythe
3344-B2|B2F.
IBM 3340/3344
UNITS
^fhe
334O/3344
diskstorage
ismade
upofa
maximum
of fourdual-drives.
Theinput/output interface isa
3340ModelA2 containingtwo independentdrives
and
theircontrollogic. Up to threeadditional
attacheddual-drives
arecontrolledby theA2 unit.
The3340ModelB contains either
oneor two drive
mechanisms.
TheModel81 containsasingledrive;
theModel
82 containstwo drives.Eachmodel
contains
allnecessaryelectronicand
power
supply
circuitsfor internaluse,but datacontroland
power
sequencing
comesfromtheA2 unit.
The
3340ModelsA2,B2,and
Bl usethe3348data
module
asastoragemedium.
The3344dual-drivemodelsuse fixedmediastorage
instead
of adatamodule.Thefollowing characteris-
ticsapply
to bothstoragedevice
types
exceptthatthe
3344
storage
capacityis279.5millionbytes-per-drive
andstart
timeisnot significant
because
thestorage
is
notmoved.
The3340/3344offersthefollowing:
o Start
time- less than20seconds
o Average
access
time- 25milliseconds
o Average
rotationaldelay
- 10.12
milliseconds
o Nominal
read/writerate
- 885,000bytes-per
second
r Data
modulecapacity
- 34,944,'768
or69,889,536
bytes
Introduction I

IBM
3340-A2
(Control
andTwo
Drives)
CONTROL
. Interprets
and
executes
macro-orders
fromthe
storagecontrol
r Regulatesthe
storagecontroland
disk
$torage
interfaces
o Serializesanddeserializes
data
r Checksdataintegrity
byerrordetection
and
error
correctionanalysis
o Furnishes
status
tothe
system
o Performs
diagnosticevaluation
ofthe
3:140/3344
storagestnng
DRIVES
o Respondstocommandsfromthe
3340-42
(controller)
o Houses,loads,filters,
anddrives
a334t|datamodule
whichhasvarious
capacities
(Models
31i,70,and
70F)
r Positions
accessmechanism
withvoice-coil
and
maintainstrackfollowing
with
electronir:servo
system
Selects
thehead
Reads
or
writes
data
Provides
safety
and
servicing
information
for
subsys-
tem
andsystemevaluation
Figurel. IBM3-140/3344 DiskStoragc
IBM 3340-8l (OneDrive),IBM 3340-82 (Two
Drives),
and IBM 3344 (Two Drives)
r Responds
to commands
from
the3340-42
(controller)
r Positionsaccessmechanismwith
voice-coiland
maintainstrackfollowingwith
electronicservo
system
r Selects
head
r Reads
and
writes
data
r Providessafetyand
servicing
informationfor subsys-
tem
andsystemevaluation
3340-81and3340-82: Houses,loads,filters,and
drives
the3348data module(s)
of various storage
capacities
(Models
35,
70,and7OF).
3344-82 and3344-B2F: Houses,filters, and
powers
two fixedmedia
drives. Each3344 drive
is
equivalent
in
capacityand
format
tofour
logical
3348Model70
volumes,
a
total
of 279.5 millionbvtesofdata.
a
a
a
2 IBM3340144ReferenceManual

STORAGT]
CONTROL
DEVICES
'[hefollowirlg
storage
control
clevicescilnaccommo-
datc31140
133,14
clisk
storiiP.o.
o 3lt30
StoragcControl lvlodel2.
o Systcnr,l-170
Moclcls
l5lt and l(rl{llltc:p'1a1sd
Storage
(
lontrol( ISC--).
r Syr;tcm7/-170 Modcl 145
lSCl.
o Sy:;tem,/370 Model 145StoragcCttntrol
Fr:ttnc
3345
Models3,
4,
and5.
o Systcm,/370
Model 135lntcgratc:clFilcAttlrch-
rnent
(lFiA).
SPECIAL
}'EATI-]RES
I'he3-14(J
drsk
storagehas
fourspecial
lcaturers
'Ihe
ModelA2 can
he'
supplied
rvith
thestrirrg
switchand
thc
rcmotcl;witch.
All 3340
ntodelscaubcordered
with Rotational
PositiclnSensing
and
Fixecl
Ilcad
Storage.
Thc 3344
tiiskstclrage
has
nospccial
leatures.
iis
Rotational
Positi<>r.r
Sensing
is
standartl.Fixed
llead
Storageisavailable.
butmust
betlrdercd
Lrynroclcl.
l'he 3344l\{oclel
R2Fcontains
l'ixed
hcadstoraqe
anti
the
Model
Il2 does
not.
String Sn'itch
'Thc
string
:i'witch
featttrc
isinstallcd
on thc3340-42
(controller) 'I'his
[e'ature
pcrrrtits
thc 3340
strinst<r
bc
dynamicully
sharecl
by two sloragecontrol
tlcvices
-I'he
fcaturc'
inclrrclcs
two intcrlockccl
F-,na[rlc,/Dis:rhlc
switchcsalkrwing
the
strirrg
1o
bc
declicirtcd
to crther
storallecontrol
ttracc:cssihle
by cach. A reulotc
contr()l
srvitch
pcnnitting
thcswitclres
to hc activatc<l
lroma l5li or l6lt Nlultipr<)ccssor
isalsolrvailablc.
3340/3344
STORAGE
CONTROL
l'age ol (i Al.6-|
(r
I
()--l
RcvrscclM:rv2('.l()76
Iiv -l'Nl.: (;N26-O.r2l{
ANDFEATURES
Rotational Pnsition Sensing
Thc Rotatittnal
Position
Sensing
(RPS)
fcattlrc-
recluces
lhechannel
contrection
timcrequirecl
to scarchfor a
given
recortlal'te
r thctrack
anclhcad
have
treen
sclccted.
This
ferature
(optional
tltlthe33"10,
stanclard
<inthe3344)
disconnects
ther
drivc
from thc
channcl
anrl
pe
rmits
otherchanne
Ioperations
to bcrlerfornred
during
the
timcrequirccl
for the
spinclle
to [rring
the
rctluircd
rccortl
to the
re
rrd
z
writchcatl.
Additi<lnal
cletails
on RPSancl
itsassociate
clconr-
mancls
arc
fottncl
inthcfollowing
ptrblicati<lns:
c Re.ferente
Mattutt/ f'or Integraled Stt;roge
C'ontrol.
Orclcr
No. CiA26-I62.0.
o Re.ft:rent'e
Manuol for -18-1
0-) StorageC'ontrol,
()rclcr
No.GA26-
1617.
F'ired FIeads
1'hc3340
lixccl
heacl
feature
pcnnits
use
ol thc
334t't-70F
data
rnodule
on ar.ry
3340
drivctl'rrt
has
[-reen
converted
for fixed
hear-l
r.rsc.This
70-mcgabytc
cleta
mclilulc
contains
lixed heads
in addititlu
ttl tl.tc
rrormal
acccss
hcacls.
With thcsc
l'ixed
heacls.500
tl.rousancl
hytcs
tll st()rage
are
availablc
that
haveze
r<r
seek
timc. Thc fcrttttre
tlocs
notittcrease
data
trroclttle
st(.)rage.
bccattse
anequivalent
ltllloLlnt
of storagu'
runctcr
thc ntovit-tq
hcldsbcconrcs
inaccessiblc.
'I'hc
3344-R2I:
clual-dril'e
isalso
cquippcd
with fixed
herd st<lragc.
ln this
nl<lclcl,
both 3344
tJrivcshavc
I.004
milliotr
fryte
s
of zero
seek
title storallc.
This
fixed
hcad
storagcis
associatecl
tlnly
with thcprimary
adrlresses
on c.tclt3344
ilrirc (sec
F-igurcs
2 antl
3).
fiorfrrrthcrelcttrils
on the I'irecl
he
adIcatttrc
arld
its
r.rscl'rtlnt:ss[()
y(lursl-oragc
rrpplication.c()lltact
\'otlr
ffJM s;.rlt:s
rcprtsctttativc
()r
sec
lhc [:i.r'etl
l]ettd
["eulrrrr
I
;.sr
rt ()uir]e.
()rdcrNo.(iAl6- l
632.
l.l+o/I1.1-+
Slontqc ( otIit-ol
lttttl
I titlLttcs

CONFIGURATIONS
'f
hevarious
configurations
of 3340/3]i44disk
storage
arc
dividcrl
intotwo groups:
configurati<tns
using
only
3340
units,,
and
configurations
using
acombination
of
3340
and
3344
units. These
attachmerrt
methods.
listed
by nrodel,
follow.
3340
STORAGE
WITHOUT 3344I
In some
System/370
models,
strings
ol'3330ancl
3350
storage
devices
can
beuscd
in addition
to the
3340s.
Model 115
(lISDDA)
Thc Modcl I 15uses
the
Direct
Drive
lr,ttachment
(DDA) for storage
control. Four
drives
can
be
attaclred:
a3340-A2
dual
drive
with control.
and
a
3340-82(dual)
or BI (single)
drive.
Model
125
(l25DDA)
The Moclel
125uses
the
DDA for stormge
control
ancl
can
ail-ach
onestring
of upto eight
332f0
drives.
Model 135
(IFA)
The Model 135
uses
theIntegrated
File
Attachment
(lFA) for storagc
control. Sixteen
drives,
two strings.
a3340string
and
astring
of either
3340
or
3333/3330drivcs
can
beattached.
Models
145,
155-II,
158,
165-II,
and
l6S
(3330-2)
Models
145,
158,
and168
(ISC)
Storage
control
for themodels
shown
irs
either
a
31330-2
or an
Integrated
Storagc
Control. The3830-2
and
eachISCpath
can
attach
upto 32 drives;
four
strings
of 3333/3330s,
3340s,or3350sin
any
cornbi-
nation.
3340
/ 3344
CONFIG
URATIONS
When
the
3344is
used,neither
3333
/333Onor3350
drivescanbe attached
to thesame
storage
conl.rol.A
3344requires
four logical
addresses
for each
drive.
only rhe135,
145,
155-II,158,
165-il,
and168
support
the3344 dualdrive.
Model
135
(IFA)
The Model 135
Integratecl
File
Attachment
has
a
maximum
of 34 logical
addresses.
'fhis
allows
two
storage
strings
to beattached:
a3340string
anda
3340/3344string
(see
Figure2).
Models 145,
155-II, 158,165-II, and 168
(3830-2)
Models 145,158,and 168
(ISC)
Sixty-fourlogical
addressescan
beused
by a3U30-2
or ISCpath
whena3340/3344 configurarion
is
attached.
Two strings
of 333O/3344s,
a3340string,
andashort
string
of four 3340drives
canbc attached.
Figure
3 shows
themaximum334O/3344
configura-
tion. Onlystrings
0 and2 canincorporate
the
3344
units. E,ach
drivehas
thehexadecimal
addrcsses
assigned
relative
to the storage
control asshown.
4 tgll 3l+0,/.1.1
Rcfercncc
Manual

02
1_9
Lq
1C
a3-
1l_
u-
1D
Drive 0 1
No,
String
1
3340-A2 3340-82 3340-82
Drive0
12345
No.
" PrimaryAddresses
lrigure
2. IFA 334013344
Maximum Configuration
(Hexadecimal Adclressing)
3340-82
Drive
No. 01
String
1
3340-A2
01
String
2
3340-A2
3340-82
Drive
No.
Drive 2 3
No.
String
3
3340-A2 3340-82
* Primary
Addresses
Figure3. ISC or 3830-2|\34013341
Maximum Configuration(Hexadecimal Addressing)
07"
27
2F
37
02*
22
2A
n
19"
1D
39
so
17*
Tr
3B
3F
16*
G
3
3E
10*
20
n
30
11*
n
n
3
18
lts 1A I re
Cor.rfigurations

P:rgc
ol'
(i, \iifr-lo t
(,-l
Rcviscd l\4rr1,
26. l()7(r
Uv I-Nt,: (lNl6-0l2l.i
IBM 3348
DATAMODULIE
DATAn*TODULE
TYPES
'fhe 3340nroclelsuscrthc IBM 334uDataN,lodulc
asrr
storagcmerJiurn.
-f
hreetypcs
areavoililble:
the334lJ
Modcl 35 with aborrt35 million
bytesof storaqe"the
33411
Moclcl
70 with about
70 milliorrt'ryies
ol'storage.
anclthe
334l;i
Model
70Frvith
about
70 rrrillion
bytes
including
one-halfmillionhytes
undcrifixu-d
hcads.
'fhe Moclt:ls
35ancl 70canbefrccly
t:xchangecl
()n
the
-l3rtOclrivcs.but therNlclclel
7()[r
canuscitsl'ixedheacls
()nlv
on 3-1,10clrivesthatl.ravebeen
convcrtcdI'or
Moclel
70F rr-se
'Ihe 334tJ-lr0Fdatanrotlulehas
tl.resanrc
char:lcteris-
tir:sasthe
3341{-70cxceptthat
r-:f
iinderrs
I thror-rgh
-5
arcacccsscdby theI'ixedheads.[)ata
r.rn
tracksuncier
thcI'ixedheacisisar,'ailablcwith onlyrotational
delay.
-fl.rc
othcr
tracks
(cylinders
0 antl{itlrr,rugh
695) are
suhje
ct to norrnnl lreaclaccess
cle
lays.
Thcthrcerlata
tii:s:
Bytc
Captcitv
Pr:rimck
Pere
vlinder
Pcrrtt,lilul,:
nroduleshavelbe
follt;vrins
charactcris-
DATA I\T0DUI-T] INITI ALIZATIII)N
All l34l{ datarlorlrrlcsarciniliiilizerlwlr,.lr
nt:rnulac-
trrrcil.llornc aclclressanrl l{-bvte
clcscri;rLors
(R0) lrrc
wriItcrron
crrchtrack.If l skipplhlcrl,.'lr:ct
i:i
fourrrl.
tlrc
q'rrttt'n
lrontc
atlclrcssconlainstlrcrtkinrlisplace-
lrcnt hvtc\. [)trrirtgn0rnral
()pcrllti(\ns
tl]e
sl,{)ra!_Ic
conlrolusesthcskip
displacenrelttbr.'tc's1obypass
llrc
dcicctivc
arca.
Il'a mcrduledata
areabccomesdefectivecluringnormal
usc,
IBN'l
utility
progranrs
areavailableto flag
dcfcc-
tivctracksandassignalicrnates
if required
(DASDI
andAII-AS for OSandAL'IDK for DOS).
DATAST-JRFACEFORMAT
Thc diskdatasurfaceis
dividecl
intoconcentricbands
of clata
calledtracks
(see
Figure4). [,ach
datirsurface
usestwo rnagnetic lcad/wr-iteheads.onefor theinsicle
irac:ksancl
onel'orthe clutsictretracks. 'Ihc rercording
surlacco1the
disk
is
clivicled
in hall'.All oddnum-
bcrecl
l.r;rcksareon onesideol'thedivitlingIinc
andall
evern
nunrhere,-'l
trircksareon the o1her.The odd inclex
point
starts
theocldtrac:ksanclthecvenindexstarts
tire
evcn. When thc lreaclsareat agivenpositior.r, they
scrvicefour tracks: oneodd, one:
even,oneinsicle.and
oneotrtsiclc.
In the334lJ-35tl:rtanr<ldulcthetracksunclcrthethree
outside
heirdsanclthoseunderthethreeinsicleheads
form acylinder.All oddnumberrcdtracks
areonone
sideof thethree
disksarrcltheeven
tracks
on theother
sidc. In asingledriverevolutioneachht:aclcoverstw<r
tracks;one
ocld.andoneeven. All cylindersare
consecrrtivelynumberedlor a total
of 34it.
I'hi:
-1341{-70
datarnodulccontair.rsfour
cltsks.J'he
track
gcomctry
isthcsamcasthatof thesmaller
data
rnoclulcwith a cvlindcrirvailablcatcach
position.
Oclcl
numhcred
cylinclersareon thc uppcrthrcesurfaccs
anclthc
cven
c5,lindersareon thc
lower
threc. Fronra
single
position
lwo consecutivc
(cven
andodci)
cyliudcrs
canhc accesscd
1sec
F'igure
5).
The'dii'fcrcricers
he
l-wccnthcstoragcmcdiauscdon thc
3340
cluta
st()ritge
unitsfollow:
3348-35 3348-70/70t,
Da(lr
Surfaccs
perMcidr"rle 3 (r
2
69(r
2
2
2
t2
24
l2
1
PhvsicallleadsnerSurlacc 2
:r348-3s
ii,36l(
l(X).4l(r
-''il.9d4.7()ll
3348--70/70F
I,368
l(x).416
6').tt39.5
3
()
l,.ogicuiCylindr:rs
pcr
Altrrrrate
Ci;
l.ogrcalf-'1,1inclcrs
pcr
Phvsic:lrl
L-ylindt:r
Physicrii'l'r;rcks
pcr
Plr-vsic:al
Cylincler
l.ogic:rl
-['rai:ks
per
I'hYsical
(--)'Iinder
|.ogicrlIracks
pcr
I ogical
(lvlintlcr
L.ogicntlrack pe r
Physical
'l
raek
Mocltrle :348
I
I
I
t)
l2
l2
1
(t llJNll"t-ll:)/-l.iltclclcnce Nlanrr;rl