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

r'l',"
i"
tr, ta
\. tt.
t'-\i-.-
i-\i_11_--:-= =1;1-j,
---
\\ -- --=-__:-_--- ./
\ -? ,./-
EVENTRACK
70Megabytes
Cylinders
001,003,
005,......699.
(heads
6-1 1
)
Even
lndex
Point
Figure
4. Data
Surface'frackl,avorrt
Odd
lndex
Point
) .,,,nr.,,
\ 000,002,
I oo4,......698.
) {rreaas
0-s)
Both Odd and Even
Cylinders. Odd tracks
fo!low
odd index;
even
tracks
follow even
index. l"*.
t
n*o'
OddCylinders
001,
003.
005,
.......699,
(heads
6-1 1
)
Even
Cylinders
000,002.
004,
......698.
(heads
0-5)
Note: /n he 3348-70Fdatantodule,
cylinders001-005 are
located
on the
bottom surfaceof thebottont disk.
Figure
5. Data
ModuleCeornetrv
1o,,.
t
'*o'
IBM3348Data
Module

FORMATS
RECORD
FORMAT
The basicunit of information recorded by the drive is
a byte consistingof eight bits. A group of bytes
separated
by a special
gapis called an area. Areas are
combined to make a record, the logical unit of inform-
ation. A record consists
of count, key, and data areas.
CountArea
The count areacontains the location of a data record
on a specifictrack and definesthe sizeof tlhekey and
data areasof the record. The count areais written
when the record isformatted and isnot changed
until
the record is reformatted.
KeyArea
Use of the key areais at the discretion of the program-
mer. When used,the key areaof the record contains
the primary identification of the data portion of the
record (such associalsecurity number, man number,
part number).
Once the key areais formatted, the contents (but not
the length) may be altered. If the key areais altered,
the data areaof the record must alsobe rewritten.
Data
Area
The data areacontainsthe information identified by
the count and key areasof the record. Data informa-
tion is organizedand arrangedby the programmer.
The length of the data areais defined by the count
area. Once the data areais formatted, the contents
(but not the length) may be altered. The contents of
the data areamay be alteredwithout affecting any
other areain the record.
TRACKFORMAT
All tracks areinitially formatted beginning at an index
point (see
Figure 6). Each track hasthe samebasic
format: home address,track descriptor record, and one
or more data records. The records.and areas
within
the records,areseparated
by gaps.
HomeAddress
Each track contains one home address,which defines
the physical location of the track (track address)
and
the condition of the track. Home address
is the first
recorded areafollowing an index point.
Specificcommandsareusedfor writing and readinga
home address
area:Write Home Address and Read
Home Address. Home address
is normally rewritten to
flag the defective track. Writing home addressesis
usuallydone at the IBM plant.
TrackDescriptorRecord
(R0)
This record is always the first record on the track
following the home addressarea. In IBM program-
ming systems,the R0 count field of the defective track
providesthe addressof the alternate track. If it is an
alternate track, the R0 count areaproyides the address
of the defective track. An 8-byte data field isusedto
storethe number of bytes remaining on the track.
Specificcommands,Write R0 and Read R0, areused
for writing and reading the track descriptor record.
Data Records
One or more data records may follow the track
descriptor record (R0) on a track. Record format is
determined at the time the count, key, and data areas
of the record are originally written by execution of a
Format Write command. The format of the record is
rewritten by another Format Write command.
Data records,aswell astrack descriptor records,can
be formatted with or without keys. Generally, file
organization determineswhether keys areused.
RECORDOVERFLOW
The record overflow function provides a means
of
processing
logical records that exceedthe capacity of a
track. When using overflow records,the cylinder
boundarv limits the sizeof the record.
8 IBM 3340144
ReferenceManual

Equallengthrecords
: 8,535
(track
capacity)
C + KL + DL (bytes/record)
Track
: 8,535
>
where:
track
where:
C(overhead/record): 167if KL : 0
=242ifKL+0
KL: Key length
DL: Data length
The number of records (n/ of different key and data
lengthsthat can be recorded on a track must satisfy
the following equation (the standardR0 is already
accounted
for):
Records n
Ic * KL(i)
+ DL(i)
i:1
167ifKL:0
242LtKL + O
TRACK CAPACITY
The numberof recordsthatcanberecordedona
track
dependsontherecordsize.Thefollowing
equation
canbeusedto determinethenumberof equal
lengthrecords
pertrack. Thehome
addressand
standardR0spaceandskipdefectaretakeninto
consideration.
WhenR0 isnotstandard,the
following
formulashould
beused:
Records
=8,'706
>-
[KL(o) + DL(o) + C-4] +
Track n
where:
f, trufil +DL(i)
+cl
i:1
c:167 if
KL:0
c:242if KL+0
The tablesshown in Figures7 through l0 give maxi-
mum sizesof n equal-length
recordson a trackwhere
n is all possible
values. Track, cylinder, and data
module capacities
aregiven in both the number of
bytes and the number of records.
There are tables for recordswithout keys,and for
recordswith keys. In all tables,overhead for home
addressandstandard
record
zero (KL : 0, DL : 8) is
already
accounted
for.
C:
C_
Formats 9

Track
Format
-.-
SD
I
PAIFICCI
HHI
DCB
(syrt.t
J
oata
G3
( (svste./
/storus.
\Control)
1'Disk
to
]storus.
o'13:lJ"'
I t0"". I
I or"" )
lt
t/
ffi
associatedgap.
G2
f-
Ro
c.*,
I
ry I
G2
Index
1\
Lrl G2
G2
INDEX: Inclicates
thebeginning
of each
trar:k.
All tracks
on
the
disk
surfar:e
are
synchronized
by Index.
G1 (Gap
1): Separates
Index
and
Home
Address.
HOME
ADDRESS
SD
(Skip
Displacemer.rt):
Storage
control
indicators
for skip
displacernentr:oncl
itionof track.
PA (Physical
r\dciress):
Storage
control
checkfor
verification.
Note: Ihe SD artdPA bytes are internal conventiorts involv-
ing only the storagecontrol and drive. The function is
transparent to the using systetn.
F (Flag):
Defines
trackcondition
asfollows:
Bit
0 - Skip
Displacement
Bits
1,2,4,
and5 --
Unused.
Bits
6 and7 00 =Normal
Track
01 = Alternate
Track
10=
I
11 | Defective
Track
The
flag
byte
rray betransferred
to andfronn
theusing
system.lt rs
tire
onlyflag
bytetransferrable,
CC
(Cylinder
Number):
Specifies
thecylinder
numDer:
For3348
35 0 to 347
For
3348-70 0 to 695
For
33487OF
0 to 695 (cylinders
1-5 fi>red
heads)
HH (Track
Nurrrber):
Specifies
thereadlwrite
tracknumber
with
theselected
cylinder:
For3348-35 0-1 1
For
3348-70 0-11
For
3348-70F
0-1 1 (cylinders
1-5 fixed
heads)
DCB(Detection
Code
Bytes): Generated
by the3340-,42
andused
for error detection.
l;igurc
6. Recordand
Track
lrornrat
l0 IBM 3340144Reference
Manual
G2
t Standard
R0
does
not containan R0 key area
or
G2
(Gap
2): Separates
home
address
and
R0
counr
area.
RECORD
ZERO
RO
COUNT
AREA
SDand
PA: Same
as
Home
Address.
F (Flag): Defines
trackcondition
identifier
for overflow
recoro
s.
Bits
0-2 * Skip Displacement
Indicators.
Bits
3 and
5 - Unused,
bit 5 is
always
zero.
Bit4 - When
on, indicates
thata logical
record
continues
on the next
track.
Bits
6 and7 - 00 = Normal
Track
01 = AlternateTrack
10=
) |
ii=l DefectiveTrack
CC
(Cylinder
Number):
Specifies
thecylinder
number:
For
3348-35 0 to347
For
3348-70 0 to 695
For
3348-70F
0to 695
(cylinders
1-5 fixed
heads)
HH(Track
Number):Specifies
theread/write
track
number
within
theselected
cvlinder.
For
3348-35
0-11
For
3348-70 0-1 1
For
3348-70F
0-1 1
(cylinders
1-5 fixed
heads)
R(Record
Number):
Normallyhas
a
value
of Hex
00.
KL (Key
Length):
Specifies
thenumber
ofbytesin
theR0
key
area,from'0-255
bytes.
For
standardR0.
this
normally
has
a
value
of Hex
00.
DL (Data
Length):
Specifies
the
number
ofbytesin
the
R0
data
area,
from 1to track
capacity.
For
standardR0,
tlris
normally
has
a
value
of Hex 08.
DCB
(Detection
CodeBytes):
Generated
bythe3340-42
and
used
tor
errordetection.

Track
Format
Disk
to
Storage
Controi
Data
I
)G3
)
G2 (Gap 2): Precedes
allkey
areas.
RO KEY
AREA
KEY AREA: ldentifies
information
in thedata
area.
For
standard
R0,this
areaisnot present
on the
track.
DCB (Detection
CodeBytes): lf key area
iswritten,
these
bytesare
generated
by the3340-42andusedfor error
detection.
G2 (Gap
2): Precedes
alldata
areas.
RO
DATA AREA
DATA AREA: Contains
theinformation
identified
bv the
count and key areas.
DCB (Detection
Code
Bytes): Generated
by the3340-42
and
usedfor error
detection
andcorrection.
DATA RECORD
COUNTAREA (R
1--Rn)
G3 (Gap 3): Precedes
all
countareas,exceptR0,
DATA
RECORD
DATARECORD
COUNTAREA
F (Flag):
SameasRecord
Zero.
CC
(Cylinder
Number):
Specifies
thecylindernumber:
For
3348-35 0to 347
For
3348-70 0 to 695
For
3348-70F0to 695
(cylinders
|
-5 fixedheads)
Index
HH (Track Number): Specifies
the read/write track
number
within theselectedcylinder:
For
3348-35 0-11
For
3348-70 0-11
For3348-70F 0-1 1 (cylinders
1-5 fixed heads)
R (Record
Number): Specifies
thesequentialnumber
of
the record
on the trackif specifiedby programmer.
KL (Key Length): Specifies
thenumber
of bytesin the
key
area,from 0-255 bytes.
DL (Data
Length): Specifies
the number
of bytesin the
data
area,
from 1to trackcapacity.
DCB (Detection
CodeBytes): Generated
by the3340-42
andusedfor error detection.
G2 (Gap
2): Precedes
allkey
areas.
DATA RECORD
KEY
AREA (R1-Rn)
KEY AREA: ldentif
iesinformation
in the
d,ataarea.
DCB(Detection
CodeBytes): Generated
by the3340-42
and usedfor error detection.
G2 (Gap
2): Precedes
alldata
areas.
DATA RECORD
DATA AREA (R1-Rn)
DATA AREA: Contains
theinformation
identified
by
thecountand key
areas.
DCB (DetectionCode Bytes): Generated
by the 3340-42
and usedfor error detectionandcorrection.
G4 {Gap 4): Paddingfrom end
of thelastdata
areato
Index. lf usedfor defectskipping,G4 iscent.ered
overthe
defect. Formats I I
Key DCB

RecordLength Track Capacity Cylinder Capacity
(DL)
(Bytes) (Records) (Bytes) (Records) (Bytes)
8,368
4,1
00
2,678
1,966
1,540
1,255
1,O52
899
781
686
608
544
489
442
442
366
335
307
282
259
239
220
204
188
174
tol
149
137
't27
't
17
108
99
91
84
76
70
63
57
51
46
41
36
.31
26
22
18
14
10
7
3
1
2
4
5
o
ti
q
10
l1
12
IJ
14
tc
to
17
18
't9
20
21
22
23
24
25
26
27
28
29
30
JI
32
JJ
34
35
36
JI
38
39
40
41
42
43
44
45
46
47
48
49
50
8,368
8,200
8,034
7,864
7,700
7,530
7,364
7,192
7,O29
6,860
6,688
6,528
6,357
6,188
6,030
5,856
5,695
5,526
5,358
5,180
5,019
4,840
4,692
4,512
4,350
4,186
4,023
3,836
3,683
3,510
3,348
3,1
68
3,003
2,856
2,660
2,520
2,331
2,166
1,989
1,840
1,68i
1,512
1,333
1,144
990
828
658
480
343
150
12
24
36
48
60
72
84
96
108
120
132
144
r56
168
180
192
204
216
228
240
252
264
276
288
300
312
324
336
348
360
372
384
396
408
420
432
444
456
468
480
492
504
516
528
540
552
564
576
588
600
100,416
98,400
96,408
94,368
92,400
90,360
88,368
86,304
84,348
82,320
80,256
78,336
76,284
74,256
72,360
70,272
68,340
66,312
64,296
62,160
60,228
58,080
56,304
54,144
52,200
50,232
48,276
46,O32
44,196
42,120
40,176
38,016
36,036
34,272
31,920
30,240
27,972
25,992
23,868
22,O80
20,'t72
't8,144
15.996
13,728
11,880
9,936
7,896
5,760
4,116
1,800
Figurc
7. Rccord
(lapacities
per
Track and
('ylinder - Without Keys
12 IBM 3340/44
ReferenceManual

MODEL
35 MODEL
7OI7OF
Records Bytes Records Bytes
4,176
8,352
12,528
16,704
20,880
25,056
29,232
33,408
37,584
41,760
45,936
50,112
54,288
58,464
62,640
66,816
70,992
75,1
68
79,344
83,520
87,696
91,872
96,048
100,224
104,400
108,576
1't2,752
116,928
121,104
125,280
129,456
133,632
137.808
14
t
,984
146,1
60
150,336
154,512
158.688
162,864
167,O40
171
,216
175,392
179,568
183,744
187,920
192,096
196,272
200,448
204,624
208,800
34,944,768
34,243,200
33,549,984
32,840,064
32,155,200
31,445,280
30,752,064
30,033,792
29.353,1
04
28,647,360
27,929,O88
27,260,928
26,546,832
25,841,O88
25,181,280
24,454,656
23,782,320
23,076,576
22,375,OO8
21,631,680
20,959,344
20,211,840
19,593,792
18,842,112
1
8.165,600
17,480,736
16,800,048
16,019,136
15,380,208
14,657,760
13,981,248
13,229,568
12,540,528
11,926,656
11
,1
08,160
10,523,520
9,734,256
9,O45,216
8,306,064
7,683,840
7,019,856
6,314,112
5,566,608
4,777,344
4,134,240
3,457,728
2,747,808
2,OO4,480
1,432,368
626,400
8,352
16,704
25,056
33,408
41,760
50,112
58,464
66,816
75,'t68
83,520
91,872
100,224
108,576
116,928
125,280
133,632
141,984
150,336
158,688
167,O40
175,392
183,744
't92,096
200,448
208,800
217,152
225,504
233,856
242,208
250,560
258,912
267,264
275,616
283,968
292,320
300,672
309,024
3',t1,376
325,728
334,080
342,432
350,784
359,1
36
367,488
375,840
384,192
392,544
400,896
409,248
4't7,600
69,889,536
68.486,400
67,099,968
65,680,128
64,310,400
62,890,560
61,504,128
60,067,584
58,706,208
57,294,720
55.858,176
54,521,856
53,093,664
51,682,176
50,362,560
48,909.312
47,564,640
46,153,152
44,750,O16
43,263,360
41,918,688
40,423,680
39,187,584
37,684,224
36,331
,200
34,961,472
33,600,096
32,038,272
30,760,416
29,315,520
27,962,496
26,459,136
25,081,056
23,853,312
22,216,320
21,047,O40
19,468,512
18,090,432
16,612,128
15,367,680
14,O39,712
12,628,224
11,133,216
9,554,688
8,268,480
6,915,456
5,495,616
4,008,960
2,864,736
1,252,800
Figurc8. Record
Capacities
per
Data Module- Without Keys
Formats l3

RecordLength Track
Capacity Cylinder
Capacity
(KL+DL)
(Bytes) (Records) (Bytes) (Recordsl (Bytes)
8,293
4,O25
2,603
1,891
1,465
't,180
977
824
706
611
533
469
414
367
327
291
260
232
207
184
164
145
129
113
99
86
74
62
52
42
33
24
'16
1
2
3
4
5
o
7
8
9
10
1',|
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
JJ
34
8,293
8,050
7,809
7,564
7,325
7.080
6,839
6,592
6,354
6,110
5,863
5,628
5,382
5,138
4,905
4,656
4,420
4,176
3,933
3,680
3,444
3,190
2,967
2,712
2,475
2,236
1,998
1,736
1,508
1,260
1,023
768
528
306
12
24
36
48
60
72
84
96
108
120
132
144
156
168
180
192
204
216
228
240
252
264
276
288
300
312
324
336
348
360
372
384
396
408
99,516
96,600
93,708
90,768
87,900
84,960
82,068
79,104
76,248
73,320
70,356
67,536
64,584
61,656
58,860
55,872
53,040
50,112
47,196
44,160
41,328
38,280
35,604
32,544
29,700
26,832
23,976
20,832
18,096
15,120
12,276
9,216
6,336
3.672
Figurc9. RecordCapacities
pcr
Track andCylinder - With Keys
14 IBM 3340144Reference
Manual

MODEL
35 MODEL
70/7OF
Records Bytes Records Bytes
4,176
8,352
12,528
16,704
20,880
25,056
29,232
33,408
37,584
4',t,760
45,936
50,112
54,288
58,464
62,640
oo,b
tb
70,992
75,1
68
79,344
83,520
87,696
91,872
96,048
100,224
104,400
108,576
112,752
116,928
121,104
125,280
129,456
133,632
137,808
141,984
34,631,568
33,616,800
32,610,384
31,587,264
30,589,200
29,566,080
28,559,664
27,528,192
26,534,304
25,515,360
24,483,888
23,502,528
22,475,232
21,456,288
20,483,280
19,443,456
18,457,920
17,438,976
16,424,208
15,367,680
14,382,144
't3,321,440
12,390,192
11
,325,312
10,335,600
9,337,536
8,343,648
7,249,536
6,297,408
5,261,760
4,272,048
3,207,168
2,204,928
1,277
,856
8,352
16,704
25,056
33,408
41,760
50,112
58,464
66,816
75,1
68
83,520
91,872
100,224
108,576
116,928
125,280
133,632
141,984
150,336
158,688
167,O40
175,392
183,744
r92,096
200,448
208,800
217
,152
225,504
233,856
242,208
250,560
258,912
267,264
275,616
283,968
69,263,136
67,233,600
65,220,768
63,174,528
61
,1
78,400
59,132,1
60
57,119,328
55,056,384
53,068,608
51,O30,120
48,56t,176
47,005,056
44,950,464
42,912,576
40,966,560
38,886,912
36,915,840
34,877,952
32,848,416
30,735,360
28,764,288
26,642,880
24,780,384
22,650,624
20,671,200
18,675,072
16,681
,296
14,499,072
12,594,816
10,523,520
8,544,096
6,41
4,336
4,409,856
2,555,712
Iigurc 10. Rccord
('upacitics
per
l)ataModrrlc Witlt
Ke1,s
Formats l5

INPUT/ OUTPUT OPERATIONS
This
section
contains
ageneral
description
of l/ O
operations
used
with IBM disk
storage
devices.
Detailed
information
about
thecentral processing
unit
andchannel
program
control
of I/O operations
is
foundin IBM System/370
Principles
o,f Operation,
OrderNo.
GA22-7000.
DEVICE SELECTION AND ADDRESSING
Device
Address
3340DRIVES
Drive addresses
arespecifiedin the I/O instruction.
The 3340 address
isspecified
in bits4, 5.,6,and7 of
theaddress
byte (byte 3); bit 3 isalso
used
with 32
drive addressing.
Any drive address
from hex 0 to F can be accepted.
Drives 0 to 7 areattachedto the first con.troller
string
and drives 8 to F on the second
string. If a logical
connection cannot be madebecause
the required drive
is offline, Unit Check (Intervention Required) is
returned. If multiple selectionis detectecl
because
of a
hardware failure, Unit Check (Intervention Required)
isreturned.
Note: Ifte drive addressesmust be wired on a
logic board in the drive units.
3344
DRIVES
For configurations r"rsing
3344 drives,lhe device
addressing
is modified to handle the multiple logical
devices
on eachspindle. Bits 2 througJr
7 of byte 3
specify the logical device(a maximum of 64) and
bits 0 and I the storagecontrol address. This
addressing
allows 3344 driveson strings0 and 2 only.
String 3 can have only two 3340 units.,
one A2 and
one B (see
Figure 3). When 3344 drivesare attached
to astoragecontrol, only334013344
clevicescan
be
controlled;3330
or3350
strings
cannotbe
attached.
SeekAddress
A specific track isselected
by sendingthe seekaddress
and a Seek
command to the required drive. Theseand
othercommands
aredescribed
in theISC and3830-2
reference
manuals.
Bytes 0 and I areunused,bytes 2 and 3 ilre the logical
cylinder
address,
andbytes 4 and5 are
thelogical
trackaddress.
All seek
addresses
consist
of sixbvtes.
012345
OOCCHH
The CCHH part of count areas
and home addresses
normally correspondsto bytes 2 through 5 of the seek
address. The physical address
(PA) bytes in each
count areaand home addressindicate physicalcylinder
and track addresses.The PA bytes are written by the
storagecontrol and are usedfor seekverification.
When the seekargument isreceivedby the storage
control, it is converted into physicalcylinder and track
addresses
and sent to the selected
drive for Seek
operations. The acceptableseekaddresses
for the
3340/3344 devices
are:
ACCESS
AND DATA TRANSFER
SPEED
The total time required for access
and data transfer
consistsof access
motion, head
selection,rotational
delay, and data transfer.
Access
MotionTime
Accessmotion time is the time required to move the
read,/write heads
to the correct cylinder. If the heads
are already at the correct cylinder, the access
time is
zero. Accesstime is alsozero for data stored under
fixed headswhen fixed head models are used.
If the accessmechanismmust move to another cylin-
der, a minimum of 10 millisecondsisrequired. The
maximumaccess
movementis50 milliseconds.
but the
averageaccess
time is 25 milliseconds.
Head Selection Time
The time required to selectthe read/write headis
negligible.
Storage
Model DataTracks AlternateTracks
cc HH cc HH
3348-35 a-347 0-'11 348 0- 11
3348-70
3348-70F 0-695 0- 11 696,697 0- 11
3344-82
3344.82F 0- 695
x4 0- 11 696,697 x4 0-11
l6 IBM3340144
Reference
Manual