IEnfi Reference Manual forSystems IBM 3340/3344 Disk Storage

G A 2 6 - 1 6 1 9 - 4 F i l e N o . 5 3 7 0 - 0 7

Reference Manual for

Systems IBM 3340/3344 Disk Storage

IEnfi

PREFACE,

This publicatic,n is intended to familiarize rCata proc- essing personnel lvith the characteristics ol' IBM

3340/3344 Disk Storage. The reader should have prior knowledge of direct-access storage dievices and concepts.

This publication is organized by topics as follows:

r I N T R O D T i C T I O N - D e s c r i b e s b a s i c u n i r s a n d lists highlights and f'unctions.

o C O N F I G T J R A T I O N S a n d A T T A C H V I E N T S - Defines sorne possi'trle combinations and svstem a t t a c h m e n t s f o r t h e 3 3 4 0 i 3 3 4 4 .

o FEAT'URF,S - Describes both standand and optional fe:rtures available for the 334(l/3344 with illustrations of some combinations.

o FORMATS - Describes and illustrates thc record and track Irtrnrats for data. Also provided are Record,i T'rack capacity charts including formulas for capacitll calculations of various length records.

o I N P U T / O L T T P U T - I n c l u d e s a d d r e s s i n g m e t h o d s . a c c e s s t i n t e s . a n d i d e n t i f i e s s e c u r i t y a n d p r i v a c y m e : a n s . L i s t s a n d s u m m a r i z e s t h e

3340/3341 command set and sense byte formats.

A l s o i n c l u d e s a n e r r o r c o n d i t i o n ta b l e a n d t h e associated {lrror recovery actions.

o O P E R A I l N G I N S T R U C T I O N S - D e s c r i b e s a l l switches anrd indicators associated with tht:

Fifth Edition (July 1975)

' I h i s

p u b f ic a t i o n r c p l a c e s arrd nrakcs Re.l'erence M a n u u l { r : r l B l l [ - t -] 4 0 D i s i S t o r a s e , O r d c r \ , r . G A 2 6 - 1 6 1 9 - 1 . o b s o l c t c .

S i g n i f i c a n t c h a t t g , : s t r r a d d i l i o n s t o t h c s p e c i f i c a t i o n s c o n t a i n c d i n t h i s n u b l i e a r r g n a r e c o n t i n u a l l y h c - i n g n t a d e . B c f o r c u s t t r g i h i s g r u b l i c z r t i o n i r r c o r r n e c t i o n w i t h t h e o p e r a t i o n o f I B M e q u i p r n e n t , c ( ) n t a c t th e l o c : r l IB M B r a n c h ( ) f l i c e f o r r c v i s i o n s . c o p i e s o f t h i s a r r d o t h e r [ 8 1 \ 1 p u b l i c a t i o n s c a n b e o b t a i n e d t h r < i u s h ll ] f u l l l r a n c l r C ) f f i c e s .

. A f o r m f o r r e a d c r ' s ro m m c l l t s i s p r o v i < 1 e d a t t h c b a c k o f l l i i s n u b l i c a l i o n , l f t h r : f o r n r h a s b e e n r e n t o v c d . s e n d v o u r c ( ) n t i n e n t : , t o t h e a d c l r e s s h , : l o w .

' f h i s

n r a n u a l w a s p r e p a r e d b y t h c I B M G c ' c r a l P r ' d u c 1 s [ ) i v i s i o n . C r a p h i c s a n d P u b l i s h i n g . D e p a r t m c n t G 2 6 . S a n . , I o s e . C l a i i f o r n i a 9 5 1 9 3 .

! : ' C o p y r i g h t l n t e r n a t i o n a l I l u s i n c s s M a c h i n e s C o r p o r a t i o n l g 7 j . 1 9 7 4 , 1 9 7 5 .

3340/3344 Operator and Power Panels. Provides suggested instructions for data module unloading and loading procedures and the EnableT'Disable Read Only Function.

The following publications are recommended for detailed information concerning the subjects covered i n t h i s m a n u a l :

c IBM System/370 Principles of Operatlon, Order N o . G A 2 2 - 7 0 0 0 .

c IBM 3348 Data Module Handling Procedures, O r d e r N o . G A 2 6 - 1 6 2 5 .

o IBM ,1 340 Disk Storage Fixed Head Feature U s e r s G u i d e . O r d e r N o . G A 2 6 - 1 6 3 2 .

c IBM Reference Manual for Integrated Storage C o n t o l . O r d e r N o . G A 2 6 - 1 6 2 0 .

o IBM Reference Manual .f-or 3830 Model 2 S t o r a g e C o n t r o l , O r d e r N o . G A 2 6 - 1 6 1 7 .

o The Data Processing Glossary, Order No. GC20-

| 699, define s terms related to direct-access storage d e v i c e s .

o Thc functional characteristics manual applicable to thc parent system. C)rcler numbers for functional characteristics manuals can be found in the IBM

.S.y.stem/ 360 and System/ 370 Bihliography, O r d e r N o . G A 2 2 - 6 8 2 2 .

ii IBM 334014'1 Re ferencc Manual

Introduction

I B M 3 : 1 4 0 D i s k S t o r a g e D a t a M o d u l e . . . . Defect Skipping

I B M 3 3 4 4 - 8 2 l l ] 2 F D i s k S t o r a g e . . . . I B M 3 3 4 0 / 3 3 4 4 U n i t s

3340/3344 Storage Clontrol and Features Storage Control Devices

S p e c i a l F e a t u r e s S t r i n g S w i t c h . . . .

Rotational Position Sensing Fixed Heirds

C o n f i g u r r a t i o n s . . . .

3340 Stc,rage Without 3344 . M o d e l i I l 5 ( 1 1 5 D D A ) M o d e t 1 ' 2 5 (1 2 5 D D A ) M o d e L 1 3 - 5 ( I F A )

M o c l e l s 1 3 5 . 1 4 5 . 1 5 5 - l l , 1 5 8 , 1 6 5 - l l , a n c l l6 8 ( 3 8 3 0 - 2 ) M o d e l s 1 4 5 , l 5 B . a n c l 1 6 8 ( l S C )

3340/3344 Configurations . . . M o d e l l . 1 5 ( I F A )

M o d e l s 1 3 5 , 1 4 5 , 1 5 5 - t l . 1 5 8 , 1 6 5 - l l . a n r l 1 6 8 ( 3 8 3 0 - 2 ) M o d e l s 1 4 5 , 1 5 8 , a n d 1 6 8 ( l S C )

IBM 33418 Data Module . . . . Data Mc,dule Types

D a t a M o ' d u h I n i t i a l i z a t i o n . . . D a t a S u r f a c c F o r m a t

Formats Record Format

Count Area K e y A r e a Data Area

T r a c k F o r m a t . . . . Home Acldress

Track Descriptor Record (R0) D a l a R e c o r d s . . . .

'frack

Capacity

Input/Output Operations

Device Selection and Addressing . . . Device Address

S e e k A d c l r e s s . . .

Access and Data T'ransfer Speed .

P a g c o l ( i A 2 6 - 1 6 1 9 - , 1 R c v i s c d M a y 1 6 . l t ) 7 6 B y ' l N L : ( ; N 2 6 - 0 1 2 t i

CONTENTS

Access Motion Time . Head Selection Time R o t a t i o n a l D e l a y . Data 'l'ransfer

l1

Data Security and Privacy . . 11

R e a d O n l y F u n c t i o n 1 1

F i l e P r o t e c t i o n . . . 1 1

S e e k V e r i f i c a t i o n . 1 1

E r r o r R e c o v e r y P r o c e d u r e . . " . 1 8 E r r o r C o r r e c t i o n F u n c t i o n . . . 1 8 E r r o r C o n d i t i o n T a b l e l t J E r r o r R e c o v e r y A c t i o n l 8

C o n s t r u c t i o n o f R e s t a r t C C W s . . . l 8 Channel Commands

Sense Commancls . Control Commands R c a d C o m m a n d s . Write Commands . S e a r c h C o m m a n d s Sense Data

S e n s e B y t e S u n t m a r y

S c n s e B y t e s O - 7 S u n t m a r y . . . , - 1 5 3 3 4 0 S e n s e B y t e F o r m a t I S u m m a r y l ( r

3344 Sense Byte Fornrat I Summary -lti

F o r m a t s l, 4 , a n d 5 M e s s a g e S u m m a r y 4 0 S e n s e B y t e F o r m a t 4 S u m m a r y 1 l

Sense Byte Format 5 Summary 4)

Sense Byte Format 6 Summary '+-3

Operating Instructions 3 3 4 0 O p e r a t o r P a n e l 3 3 4 4 O p e r a t o r P a n e l 3 3 4 0 / 3 3 4 4 P o w e r P a n e l .

Machines Without String Switch Feature M a c h i n e s W i t h S t r i n s S w i t c h F e a t u r e Data Module Loading

Data Module Unloading 4()

R e a d O n l y F u n c t i o n ' + 7

Enable Read Only F-unction 1'1

D i s a b l e R e a d O n l y F u n c t i o n 1 l

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FIGURES

F i g u r e l.

F i g u r e 2 . F i g u r e 3 . F i g u r c 4 . F i g u r e 5 . l'igure b.

F i g u r e 7 . F i g u r c 8 . F i g u r c 9 . F i g u r e 1 0 . Irigure I I . F i g u r e 1 2 .

I t t l v l 3 3 4 0 / : 1 , 1 4 4 D i s k S t o r a i r e . . .

I F A 3 3 4 0 / - i 3 4 4 M a x i m u n r C e n l ' i s u r a l i o n I S C o r 3 I J 3 0 - 2 M a x i m u r n L l o n l " i s u r a t i o n

l ) a t a S u r f a c e ' l ' r a c k l - a y , o u t . . . . .

l ) a t a M o d u l e ( i e o n r c t r v l { e c o r d a n d ' l ' r a c k F o r m a r

l ' r a c k , / ( l y i i n c l c r C : . i p a c i t i r : s - No Kcls . D a r t a M o d u l e C a p a c i t i c s - Ntr Keys . . . . - l - r a c k , / C y l i n c l e

r C a p r a c r t r c s , Wirh Kcys D a t a f r 4 o d u i e C a p a c i t i c r , V ' 1 i r h K L : y ' s Errclr C<inclitiorr fehlc

R c c o v e r y A c t i o r r ' l a b l c .

l i c : n s e L u r n r n a n d \ ( lontrol (. onrnrirrrils R c a c i ( - o r n n r a r r d s W r i t . e ( . ' o r n m a n L l s S e a r c h ( . ' o r n n r a r r r l s

S c r r s c [3 y t . e s ( . ] - J S u m n r a r y . . . . - J - 1 . 1 0 l ' o r r l r a t i 5 c ; t s c l l t t c S u n i l t r a r v . . . . - l . l - 1 . 1 l o r r r u r l I S c n : ; c B y t c S u n r u t a r y " . - . l r o r m a t s l . 4 , a n d 5 M e s s a p ' . q ' S u r n i r r . r r v F o r n t . r t -l S u l r r n r r r y

I o l m u t - 5 S u r t ) n l i i r ) F r r f i l l i - r l 6 S u t i l n l l t r v

O p c r a t o r P a n c : i , ll - 1 4 0 a n c l 3 j " l 4 "

P o w c r l ) a r r e l , 3 3 4 f ) / 3 3 4 1 l j a t a M o d u l e [ . o a d , ' L i n l r r e d l l t t r t l ( ) l r i v l , r r ( l l . t l

5 )

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l l , 1 5 3 6 -18 10 4 l .1 ,l -tr.1 :i4 ,16 ,47

i t l l J \ l . i . l J U , . + + R c l u , r r . t r . t ' I i l r r r u : r l

The IBM 3340 Disk Storage provides direct-

a c c e s s s t o r a g e f o r I B M S y s t e m / 3 7 0 M o d e l s I 1 5 , 1 2 5 , 1 3 5 , 1 4 5 , 1 5 5 - I I , 1 5 8 , 1 6 5 - I I , a n d 1 6 8 . T h e 3 3 4 0 consists of a Model 42, control with dual-drive disk storage, and up to three attached dual (B2) or single (Bl) drive units. The 3344large-capacity, dual-drive unit can be substituted for the 3340 B-type units o n I B M S y s t e m / 3 7 0 M o d e l s 1 3 5 , 1 4 5 , 1 5 5 - l l , 1 5 8 .

1 6 5 - I I , a n d 1 6 8 .

The 3340/3344 is a modular, high-speed, large- capacity disk storage subsystem for data base, data communication, or general purpose use.

IBM 3340 DISK STORAGE

The IBM 3340 direct-access storage introduces two technological advances: a data module and defect skipping.

Data Module

The sealed data module cartridge contains storage disks, drive spindle, read and write heads, and access arms. The data module has several advantages over a disk pack:

o The drive data storage capacity can be changed by using a different data module.

o The heads, storage disks, and drive spindle are sealed inside the data module. This avoids contam- ination from outside sources and reduces preven- tive maintenance.

o Reliability is improved as each head reads only the data that it previously wrote.

Defect Skipping

Defect skipping allows data to be stored both ahead of and following a surface defect. All of the recording track can be used except for minute portions. Since the heads no longer need be moved to an alternate track, access time is saved.

Data module capacity is not changed by defect skip- ping and t.he user is rinaware of defects.

INTRODUCTION

IBM 3344-B2IB2F DISK STORAGE

The IBM 3344-BZlB2F dual-drive unit provides increased capacity, lower-cost-per-byte, direct access storage. Each 3344 drive stores four times the

quantity of data of a 7O-megabyte data module by using fixed media. The 3344 dual drives can replace the 3340 B-drives in a 3340 string on IBM System/

3 7 0 M o d e l s 1 3 5 , 1 4 5 , 1 5 5 - I I , 1 5 8 , 1 6 5 - I I , a n d 1 6 8 . The 3344-B2F contains fixed head storage.

Defect skipping, similiar to that used on the 3340, is also used by the 3344-B2|B2F.

IBM 3340/3344 UNITS

^fhe 334O/3344 disk storage is made up of a maximum of four dual-drives. The input/output interface is a 3340 Model A2 containing two independent drives and their control logic. Up to three additional attached dual-drives are controlled by the A2 unit.

The 3340 Model B contains either one or two drive mechanisms. The Model 81 contains a single drive;

the Model 82 contains two drives. Each model contains all necessary electronic and power supply circuits for internal use, but data control and power sequencing comes from the A2 unit.

The 3340 Models A2,B2, and Bl use the 3348 data module as a storage medium.

The 3344 dual-drive models use fixed media storage instead of a data module. The following characteris- tics apply to both storage device types except that the 3344 storage capacity is279.5 million bytes-per-drive and start time is not significant because the storage is not moved.

The 3340/3344 offers the following:

o Start time - less than 20 seconds o Average access time - 25 milliseconds o Average rotational delay - 10.12 milliseconds o Nominal read/write rate - 885,000 bytes-per

second

r Data module capacity - 34,944,'768 or 69,889,536 bytes

Introduction I

I B M 3 3 4 0 - A 2 (C o n t r o l a n d T w o Drives)

C O N T R O L

. I n t e r p r e t s a n d e x e c u t e s m a c r o - o r d e r s f r o m t h e storage control

r R e g u l a t e s t h e s t o r a g e c o n t r o l a n d d i s k $ t o r a g e interfaces

o S e r i a l i z e s a n d d e s e r i a l i z e s d a t a

r Checks data integrity by error detection and error c o r r e c t i o n a n a l y s i s

o F u r n i s h e s s t a t u s t o t h e s y s t e m

o P e r f o r m s d i a g n o s t i c e v a l u a t i o n o f t h e 3 : 1 4 0 / 3 3 4 4 storage stnng

D R I V E S

o R e s p o n d s t o c o m m a n d s f r o m t h e 3 3 4 0 - 4 2 ( c o n t r o l l e r )

o H o u s e s , l o a d s , f i l t e r s , a n d d r i v e s a 3 3 4 t | d a t a m o d u l e w h i c h h a s v a r i o u s c a p a c i t i e s ( M o d e l s 3 1 i , 7 0 , a n d 7 0 F )

r P o s i t i o n s a c c e s s m e c h a n i s m w i t h v o i c e - c o i l a n d m a i n t a i n s t r a c k fo l l o w i n g w i t h e l e c t r o n i r : s e r v o system

Selects the head R e a d s o r w r i t e s d a t a

P r o v i d e s s a f e t y a n d s e r v i c i n g i n f o r m a t i o n f o r s u b s y s - t e m a n d s y s t e m e v a l u a t i o n

Figure l. IBM 3-140/3344 Disk Storagc

I B M 3 3 4 0 - 8 l ( O n e D r i v e ) , I B M 3 3 4 0 - 8 2 ( T w o D r i v e s ) , a n d I B M 3 3 4 4 ( T w o D r i v e s )

r R e s p o n d s t o c o m m a n d s f r o m t h e 3 3 4 0 - 4 2 ( c o n t r o l l e r )

r P o s i t i o n s a c c e s s m e c h a n i s m w i t h v o i c e - c o i l a n d m a i n t a i n s t r a c k fo l l o w i n g w i t h e l e c t r o n i c s e r v o system

r Selects head

r R e a d s a n d w r i t e s d a t a

r Provides safety and servicing information for subsys- t e m a n d s y s t e m e v a l u a t i o n

3 3 4 0 - 8 1 a n d 3 3 4 0 - 8 2 : H o u s e s , l o a d s , f i l t e r s , a n d drives the 3348 data module(s) of various storage c a p a c i t i e s ( M o d e l s 3 5 , 7 0 , a n d 7 O F ) .

3 3 4 4 - 8 2 a n d 3 3 4 4 - B 2 F : H o u s e s , f i l t e r s , a n d p o w e r s two fixed media drives. Each 3344 drive is equivalent in c a p a c i t y a n d fo r m a t to f o u r l o g i c a l 3 3 4 8 M o d e l 7 0 v o l u m e s , a t o t a l o f 2 7 9 . 5 m i l l i o n b v t e s o f d a t a .

a a a

2 IBM 3340144 Reference Manual

STORAGT] CONTROL DEVICES

' [ h e

f o l l o w i r l g s t o r a g e c o n t r o l c l e v i c e s c i l n a c c o m m o - d a t c 3 1 1 4 0 1 3 3 , 1 4 c l i s k s t o r i i P . o .

o 3 l t 3 0 S t o r a g c C o n t r o l l v l o d e l 2 .

o S y s t c n r , l - 1 7 0 M o c l c l s l5 l t a n d l ( r l { l l l t c : p ' 1 a 1 s d S t o r a g e ( lontrol ( ISC--).

r S y r ; t c m 7 / - 1 7 0 M o d c l 1 4 5 l S C l .

o S y : ; t e m , / 3 7 0 M o d e l 1 4 5 S t o r a g c C t t n t r o l F r : t t n c 3 3 4 5 M o d e l s 3 , 4 , a n d 5 .

o S y s t c m , / 3 7 0 M o d e l 1 3 5 l n t c g r a t c : c l F i l c A t t l r c h - r n e n t ( l F i A ) .

SPECIAL }'EATI-]RES

I ' h e 3 - 1 4 ( J d r s k s t o r a g e h a s f o u r s p e c i a l l c a t u r e r s ' I h e M o d e l A 2 c a n h e ' s u p p l i e d r v i t h t h e s t r i r r g s w i t c h a n d t h c r c m o t c l ; w i t c h . A l l 3 3 4 0 n t o d e l s c a u b c o r d e r e d w i t h R o t a t i o n a l P o s i t i c l n S e n s i n g a n d F i x e c l I l c a d S t o r a g e .

T h c 3 3 4 4 t i i s k s t c l r a g e h a s n o s p c c i a l l e a t u r e s . i i s R o t a t i o n a l P o s i t i < > r . r S e n s i n g i s s t a n d a r t l . F i x e d l l e a d S t o r a g e i s a v a i l a b l e . b u t m u s t b e t l r d e r c d L r y n r o c l c l . l ' h e 3 3 4 4 l \ { o c l e l R 2 F c o n t a i n s l' i x e d h c a d s t o r a q e a n t i t h e M o d e l I l 2 d o e s n o t .

S t r i n g S n ' i t c h ' T h c

s t r i n g :i ' w i t c h f e a t t t r c is i n s t a l l c d o n t h c 3 3 4 0 - 4 2 ( c o n t r o l l e r ) ' I ' h i s

[ e ' a t u r e p c r r r t i t s t h c 3 3 4 0 s t r i n s t < r b c d y n a m i c u l l y s h a r e c l b y t w o s l o r a g e c o n t r o l t l c v i c e s - I ' h e

f c a t u r c ' i n c l r r c l c s t w o i n t c r l o c k c c l F - , n a [ r l c , / D i s : r h l c s w i t c h c s a l k r w i n g th e s t r i r r g 1 o b c d e c l i c i r t c d t o c r t h e r s t o r a l l e c o n t r o l t t r a c c : c s s i h l e b y c a c h . A r e u l o t c c o n t r ( ) l s r v i t c h p c n n i t t i n g th c s w i t c l r e s t o h c a c t i v a t c < l l r o m a l 5 l i o r l 6 l t N l u l t i p r < ) c c s s o r i s a l s o lr v a i l a b l c .

3340/3344 STORAGE CONTROL

l ' a g e o l ( i A l . 6 - | ( r I ( ) - - l R c v r s c c l M : r v 2 ( ' . l ( ) 7 6 I i v - l ' N l . : ( ; N 2 6 - O . r 2 l {

AND FEATURES

R o t a t i o n a l P n s i t i o n S e n s i n g

T h c R o t a t i t t n a l P o s i t i o n S e n s i n g ( R P S ) f c a t t l r c - r e c l u c e s l h e c h a n n e l c o n t r e c t i o n t i m c r e q u i r e c l t o s c a r c h fo r a g i v e n r e c o r t l a l ' t e r t h c t r a c k a n c l h c a d h a v e t r e e n s c l c c t e d . T h i s f e r a t u r e ( o p t i o n a l tl t l t h e 3 3 " 1 0 , s t a n c l a r d

< i n th e 3 3 4 4 ) d i s c o n n e c t s t h e r d r i v c f r o m t h c c h a n n c l a n r l p e rm i t s o t h e r c h a n n e I o p e r a t i o n s t o b c r l e r f o r n r e d d u r i n g t h e t i m c r e q u i r c c l f o r t h e s p i n c l l e t o [ r r i n g th e r c t l u i r c d rc c o r t l to t h e r e rr d z w r i t c h c a t l .

A d d i t i < l n a l c l e t a i l s o n R P S a n c l it s a s s o c i a t e c l c o n r - m a n c l s a r c f o t t n c l i n t h c f o l l o w i n g p t r b l i c a t i < l n s : c Re.ferente Mattutt/ f'or Integraled Stt;roge

C ' o n t r o l . O r c l c r N o . C i A 2 6 - I 6 2 . 0 .

o Re.ft:rent'e Manuol for -18-1 0-) Storage C'ontrol, ( ) r c l c r N o . G A 2 6 - 1 6 1 7 .

F'ired FIeads

1 ' h c 3 3 4 0 l i x c c l h e a c l f e a t u r e p c n n i t s u s e o l t h c 3 3 4 t ' t - 7 0 F d a t a r n o d u l e o n a r . r y 3 3 4 0 d r i v c t l ' r r t h a s [ - r e e n c o n v e r t e d f o r f i x e d h e a r - l r . r s c . T h i s 7 0 - m c g a b y t c cleta mclilulc contains lixed heads in addititlu ttl tl.tc

r r o r m a l a c c c s s h c a c l s . W i t h t h c s c l' i x e d h e a c l s . 5 0 0 t l . r o u s a n c l h y t c s t l l s t ( ) r a g e a r e a v a i l a b l c t h a t h a v e z e r< r s e e k ti m c . T h c f c r t t t t r e t l o c s n o t i t t c r e a s e d a t a t r r o c l t t l e s t ( . ) r a g e . b c c a t t s e a n e q u i v a l e n t l t l l l o L l n t o f s t o r a g u ' r u n c t c r t h c n t o v i t - t q h c l d s b c c o n r c s i n a c c e s s i b l c . ' I ' h c

3 3 4 4 - R 2 I : c l u a l - d r i l ' e i s a l s o c q u i p p c d w i t h f i x e d h e rd s t < l r a g c . l n t h i s n l < l c l c l , b o t h 3 3 4 4 t J r i v c s h a v c

I . 0 0 4 m i l l i o t r fr y t e s o f z e r o s e e k ti t l e s t o r a l l c . T h i s f i x e d h c a d s t o r a g c is a s s o c i a t e c l t l n l y w i t h t h c p r i m a r y a d r l r e s s e s o n c . t c l t 3 3 4 4 i l r i r c ( s e c F - i g u r c s 2 a n t l 3 ) . f i o r f r r r t h c r e l c t t r i l s o n t h e I ' i r e c l h e a d I c a t t t r c a r l d it s r . r s c l ' r t l n t : s s [ ( ) y ( l u r s l - o r a g c r r p p l i c a t i o n . c ( ) l l t a c t \ ' o t l r f fJM s;.rlt:s rcprtsctttativc ()r sec lhc [:i.r'etl l]ettd

[ " e u l r r r r I ; . s r r t ( ) u i r ] e . () r d c r N o . ( i A l 6 - l 6 3 2 .

l . l + o / I 1 . 1 - + S l o n t q c ( o t I i t - o l lt t t t l I t i t l L t t c s

CONFIGURATIONS

' f

h e v a r i o u s c o n f i g u r a t i o n s o f 3 3 4 0 / 3 ] i 4 4 d i s k s t o r a g e a r c d i v i d c r l in t o t w o g r o u p s : configurati<tns u s i n g o n l y 3 3 4 0 u n i t s , , a n d c o n f i g u r a t i o n s u s i n g a c o m b i n a t i o n o f 3 3 4 0 a n d 3 3 4 4 u n i t s . T h e s e a t t a c h m e r r t m e t h o d s . l i s t e d b y n r o d e l , f o l l o w .

3340 STORAGE WITHOUT 3344I

I n s o m e S y s t e m / 3 7 0 m o d e l s , s t r i n g s ol'3330 ancl 3350 s t o r a g e d e v i c e s c a n b e u s c d in a d d i t i o n to t h e 3340s.

M o d e l 1 1 5 ( l I S D D A )

T h c M o d c l I 1 5 u s e s th e D i r e c t D r i v e lr,ttachment ( D D A ) f o r storage c o n t r o l . F o u r d r i v e s c a n b e a t t a c l r e d : a 3 3 4 0 - A 2 d u a l d r i v e w i t h control. and a 3 3 4 0 - 8 2 ( d u a l ) o r B I ( s i n g l e ) d r i v e .

M o d e l 1 2 5 ( l 2 5 D D A )

T h e M o c l e l 1 2 5 u s e s th e D D A f o r s t o r m g e c o n t r o l a n c l c a n a i l - a c h o n e s t r i n g o f u p t o e i g h t 3 3 2 f 0 d r i v e s . M o d e l 1 3 5 ( I F A )

T h e M o d e l 1 3 5 u s e s th e I n t e g r a t e d F i l e A t t a c h m e n t ( l F A ) f o r s t o r a g c control. Sixteen drives, two strings.

a 3 3 4 0 s t r i n g a n d a s t r i n g o f e i t h e r 3340 or 3 3 3 3 / 3 3 3 0 d r i v c s c a n b e a t t a c h e d .

M o d e l s 1 4 5 , 1 5 5 - I I , 1 5 8 , 1 6 5 - I I , a n d l6 S ( 3 3 3 0 - 2 ) Models 145, 158, and 168 (ISC)

S t o r a g e c o n t r o l f o r t h e m o d e l s s h o w n ir s e i t h e r a 3 1 3 3 0 - 2 o r a n I n t e g r a t e d S t o r a g c C o n t r o l . T h e 3 8 3 0 - 2 a n d e a c h I S C p a t h c a n a t t a c h u p t o 32 drives; four s t r i n g s o f 3 3 3 3 / 3 3 3 0 s , 3 3 4 0 s , o r 3 3 5 0 s in a n y c o r n b i - n a t i o n .

3340 / 3344 CONFIG URATIONS

W h e n t h e 3 3 4 4 i s u s e d , n e i t h e r 3 3 3 3 /333O nor 3350 drives can be attached to the same storage conl.rol. A 3 3 4 4 r e q u i r e s f o u r l o g i c a l a d d r e s s e s f o r e a c h d r i v e . o n l y r h e 1 3 5 , 1 4 5 , 1 5 5 - I I , 1 5 8 , 1 6 5 - i l , a n d 1 6 8 support the 3344 dual drive.

Model 135 (IFA)

T h e M o d e l 1 3 5 I n t e g r a t e c l F i l e A t t a c h m e n t h a s a m a x i m u m o f 3 4 l o g i c a l a d d r e s s e s . ' f h i s

a l l o w s tw o s t o r a g e s t r i n g s to b e a t t a c h e d : a 3 3 4 0 s t r i n g a n d a 3 3 4 0 / 3 3 4 4 s t r i n g ( s e e F i g u r e 2 ) .

M o d e l s 1 4 5 , 1 5 5 - I I , 1 5 8 , 1 6 5 - I I , a n d 1 6 8 ( 3 8 3 0 - 2 ) M o d e l s 1 4 5 , 1 5 8 , a n d 1 6 8 ( I S C )

S i x t y - f o u r lo g i c a l a d d r e s s e s c a n b e u s e d b y a 3 U 3 0 - 2 o r I S C p a t h w h e n a 3 3 4 0 / 3 3 4 4 c o n f i g u r a r i o n i s a t t a c h e d . T w o s t r i n g s o f 3 3 3 O / 3 3 4 4 s , a 3 3 4 0 s t r i n g , a n d a s h o r t s t r i n g o f f o u r 3 3 4 0 d r i v e s c a n b c a t t a c h e d . F i g u r e 3 s h o w s th e m a x i m u m 3 3 4 O / 3 3 4 4 c o n f i g u r a - t i o n . O n l y s t r i n g s 0 a n d 2 c a n i n c o r p o r a t e t h e 3 3 4 4 units. E,ach drive has the hexadecimal addrcsses assigned relative to the storage control as shown.

4 t g l l 3 l + 0 , / . 1 . 1 R c f e r c n c c M a n u a l

02 1_9 Lq

1 C

a3- 1l_

u-

1 D D r i v e 0 1

N o ,

String 1

3340-A2

3340-82 3340-82

D r i v 1 e 2 0 3 4 5

N o .

" Primary Addresses

l r i g u r e 2 . I F A 3 3 4 0 1 3 3 4 4 M a x i m u m C o n f i g u r a t i o n ( H e x a d e c i m a l A d c l r e s s i n g )

3340-82

D r i v e N o .

0 1

String 1 3340-A2

0 1

String 2 3340-A2

3340-82

D r i v e N o .

D r i v e 2 3 N o .

String 3

3340-A2

3340-82

* Primary Addresses

F i g u r e 3 . I S C o r 3 8 3 0 - 2 | \ 3 4 0 1 3 3 4 1 M a x i m u m C o n f i g u r a t i o n ( H e x a d e c i m a l A d d r e s s i n g )

0 7 "

2 7 2 F 3 7 02*

2 2 2 A

n

19"

1 D 39

so

1 7 *

Tr

3 B 3 F

1 6 *

G

3 3 E 1 0 *

2 0

n

30

1 1 *

n n

3

1 8 l t s 1 A I r e

Cor.rfigurations

P : r g c o l ' ( i , \ i i f r - l o t ( , - l R c v i s c d l \ 4 r r 1 , 2 6 . l ( ) 7 ( r U v I - N t , : ( l N l 6 - 0 l 2 l . i

IBM 3348 DATA MODULIE

DATA n*TODULE TYPES

' f h e

3 3 4 0 n r o c l e l s u s c r t h c I B M 3 3 4 u D a t a N , l o d u l c a s r r s t o r a g c m e r J i u r n . - f

h r e e ty p c s a r e a v o i l i l b l e : t h e 3 3 4 l J M o d c l 3 5 w i t h a b o r r t 3 5 m i l l i o n b y t e s o f s t o r a q e " t h e 3 3 4 1 1 M o c l c l 7 0 w i t h a b o u t 7 0 m i l l i o r r t' r y i e s o l ' s t o r a g e . a n c l t h e 3 3 4 l ; i M o d e l 7 0 F r v i t h a b o u t 7 0 r r r i l l i o n b y t e s i n c l u d i n g o n e - h a l f m i l l i o n h y t e s u n d c r i f i x u - d h c a d s . ' f h e

M o c l t : l s 3 5 a n c l 7 0 c a n b e f r c c l y t : x c h a n g e c l ( ) n the -l3rtO clrivcs. but ther Nlclclel 7()[r can usc its l'ixed heacls ( ) n l v on 3-1,10 c l r i v e s t h a t l . r a v e b e e n c o n v c r t c d I' o r M o c l e l 7 0 F r r - s e

' I h e

3 3 4 t J - l r 0 F d a t a n r o t l u l e h a s tl . r e s a n r c c h a r : l c t e r i s - t i r : s a s t h e 3 3 4 1 { - 7 0 c x c e p t th a t r - : f i i n d e r r s I t h r o r - r g h - 5 a r c a c c c s s c d b y t h e I ' i x e d h e a d s . [ ) a t a r . r n t r a c k s u n c i e r t h c I ' i x e d h e a c i s i s a r , ' a i l a b l c w i t h o n l y r o t a t i o n a l d e l a y . - f l . r c

o t h c r t r a c k s ( c y l i n d e r s 0 a n t l { i t l r r , r u g h 6 9 5 ) a r e s u h j e c t t o n o r r n n l lr e a c l a c c e s s c l e l a y s .

T h c t h r c e rl a t a t ii : s :

B y t c C a p t c i t v P r : r im c k P e r e v l i n d e r P c r r t t , l i l u l , :

n r o d u l e s h a v e lb e f o l l t ; v r i n s c h a r a c t c r i s -

D A T A I \ T 0 D U I - T ] I N I T I A L I Z A T I I I ) N

A l l l 3 4 l { d a t a r l o r l r r l c s a r c i n i l i i i l i z e r l w l r , . l r n t : r n u l a c - t r r r c i l . l l o r n c a c l c l r e s s a n r l l{ - b v t e c l c s c r i ; r L o r s ( R 0 ) l r r c w r i I t c r r o n c r r c h t r a c k . I f l s k i p p l h l c rl , . ' l r : c t i : i fo u r r r l . t l r c q ' r r t t t ' n lr o n t c a t l c l r c s s c o n l a i n s tl r c r t k i n rl i s p l a c e - l r c n t h v t c \ . [ ) t r r i r t g n 0 r n r a l () p c r l l t i ( \ n s t l ] e s l , { ) r a ! _ I c c o n l r o l u s e s t h c s k i p d i s p l a c e n r e l t t b r . ' t c ' s 1 o b y p a s s l l r c d c i c c t i v c a r c a .

I l ' a m c r d u l e d a t a a r e a b c c o m e s d e f e c t i v e c l u r i n g n o r m a l u s c , IB N ' l u t i l i t y p r o g r a n r s a r e a v a i l a b l e t o f l a g d c f c c - t i v c t r a c k s a n d a s s i g n a l i c r n a t e s i f r e q u i r e d (D A S D I a n d A I I - A S f o r O S a n d A L ' I D K f o r D O S ) .

DATA ST-JRFACE FORMAT

T h c d i s k d a t a s u r f a c e is d i v i d e c l i n t o c o n c e n t r i c b a n d s o f c l a t a c a l l e d tr a c k s ( s e e F i g u r e 4 ) . [ , a c h d a t i r s u r f a c e u s e s t w o r n a g n e t i c l c a d / w r - i t e h e a d s . o n e f o r t h e i n s i c l e irac:ks ancl one l'or the clutsictre tracks. 'Ihc

rercording s u r l a c c o 1 t h e d i s k i s c l i v i c l e d i n h a l l ' . A l l o d d n u m - b c r e c l l . r ; r c k s a r e o n o n e s i d e o l ' t h e d i v i t l i n g Ii n c a n d a l l evern nunrhere,-'l trircks are on the o1her. The odd inclex p o i n t s t a r t s th e o c l d tr a c : k s a n c l th e c v e n i n d e x s t a r t s t i r e e v c n . W h e n t h c l r e a c l s a r e a t a g i v e n p o s i t i o r . r , t h e y s c r v i c e fo u r t r a c k s : o n e o d d , o n e : e v e n , o n e i n s i c l e . a n d o n e o t r t s i c l c .

I n t h e 3 3 4 l J - 3 5 t l : r t a n r < l d u l c t h e t r a c k s u n c l c r t h e t h r e e o u t s i d e h e i r d s a n c l th o s e u n d e r t h e t h r e e in s i c l e h e a d s f o r m a c y l i n d e r . A l l o d d n u m b e r r c d t r a c k s a r e o n o n e s i d e o f t h e t h r e e d i s k s a r r c l t h e e v e n t r a c k s o n t h e o t h e r s i d c . I n a s i n g l e d r i v e r e v o l u t i o n e a c h h t : a c l c o v e r s tw < r t r a c k s ; o n e o c l d . a n d o n e e v e n . A l l c y l i n d e r s a r e c o n s e c r r t i v e l y n u m b e r e d lo r a t o t a l o f 3 4 i t .

I ' h i : - 1 3 4 1 { - 7 0 d a t a r n o d u l c c o n t a i r . r s f o u r c l t s k s . J ' h e t r a c k g c o m c t r y is t h c s a m c a s t h a t o f t h e s m a l l e r d a t a r n o c l u l c w i t h a c v l i n d c r ir v a i l a b l c a t c a c h p o s i t i o n . O c l c l n u m h c r e d c y l i n c l e r s a r e o n t h c u p p c r t h r c e s u r f a c c s a n c l th c c v e n c 5 , l i n d e r s a r e o n t h c l o w e r t h r e c . F r o n r a s i n g l e p o s i t i o n lw o c o n s e c u t i v c ( c v e n a n d o d c i ) c y l i u d c r s c a n h c a c c e s s c d 1 s e c F ' i g u r e 5 ) .

T h e ' d i i ' f c r c r i c e r s h e l- w c c n t h c s t o r a g c m c d i a u s c d o n t h c 3 3 4 0 c l u t a s t ( ) r i t g e u n i t s f o l l o w :

3 3 4 8 - 3 5 3 3 4 8 - 7 0 / 7 0 t ,

D a ( l r S u r f a c c s p e r M c i d r " r l e 3 ^{( r}

2 69(r

2 2 2 t 2 2 4 l 2

1

P h v s i c a l l l e a d s n e r S u r l a c c 2

:r348-3s

i i , 3 6 l ( l ( X ) . 4 l ( r - ' ' i l . 9 d 4 . 7 ( ) l l

3 3 4 8 - - 7 0 / 7 0 F I , 3 6 8 l ( x ) . 4 1 6 6 ' ) . t t 3 9 . 5 3 ()

l , . o g i c u i C y l i n d r : r s p c r A l t rr r r a t e C i ;

l .ogrcal f-'1,1 inclcrs pcr P h v s i c : l r l L - y l i n d t : r P h y s i c r i i ' l ' r ; r c k s p c r

Plr-vsic:al Cylincler l . o g i c : r l - [ ' r a i : k s

p e r I ' h Y s i c a l ( - - ) ' I i n d e r

| . o g i c r l I r a c k s p c r I o g i c a l ( l v l i n t l c r L . o g i c n t l r a c k p e r

P h y s i c a l ' l r a e k

M o c l t r l e : 3 4 8 I I

I t)

l 2 l 2

1

( t l l J N l l " t - l l : ) / - l . i l t c l c l c n c e N l a n r r ; r l

r' l'," i"

t r , t a \ . t t .

t ' - \ i - . -

i-\i_11_--:-= =1;1-j, _\\ ^{- - -} -- --=-__:-_--- ./

\ - ? , . / -

EVEN TRACK 70 Megabytes

C y l i n d e r s 0 0 1 , 0 0 3 , 0 0 5 , . . . 6 9 9 . ( h e a d s 6 - 1 1 )

Even lndex Point

F i g u r e 4 . D a t a S u r f a c e ' f r a c k l,avorrt

Odd lndex Point

) . , , , n r . , ,

\ 0 0 0 , 0 0 2 , I o o 4 , . . . 6 9 8 . )

{rreaas 0-s)

Both Odd and Even Cylinders. Odd tracks f o ! l o w o d d i n d e x ; e v e n t r a c k s fo l l o w e v e n in d e x .

l"*.

t

n*o'

O d d C y l i n d e r s 0 0 1 , 0 0 3 . 0 0 5 , .. . . 6 9 9 , ( h e a d s 6 - 1 1 )

E v e n C y l i n d e r s 0 0 0 , 0 0 2 . 0 0 4 , .. . . 6 9 8 . ( h e a d s 0 - 5 )

Note: /n he 3348-70F data ntodule, cylinders 001-005 are located on the bottom surface of the bottont disk.

F i g u r e 5 . D a t a M o d u l e Ceornetrv

1o,,.

t '*o'

IBM 3348 Data Module

FORMATS

RECORD FORMAT

The basic unit of information recorded by the drive is a byte consisting of eight bits. A group of bytes separated by a special gap is 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.

Count Area

The count area contains the location of a data record on a specific track and defines the size of tlhe key and data areas of the record. The count area is written when the record is formatted and is not changed until the record is reformatted.

Key Area

Use of the key area is at the discretion of the program- mer. When used, the key area of the record contains the primary identification of the data portion of the record (such as social security number, man number, part number).

Once the key area is formatted, the contents (but not the length) may be altered. If the key area is altered, the data area of the record must also be rewritten.

Data Area

The data area contains the information identified by the count and key areas of the record. Data informa- tion is organized and arranged by the programmer.

The length of the data area is defined by the count area. Once the data area is formatted, the contents (but not the length) may be altered. The contents of the data area may be altered without affecting any other area in the record.

TRACK FORMAT

All tracks are initially formatted beginning at an index point (see Figure 6). Each track has the same basic format: home address, track descriptor record, and one or more data records. The records. and areas within the records, are separated by gaps.

Home Address

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 area following an index point.

Specific commands are used for writing and reading a home address area: Write Home Address and Read Home Address. Home address is normally rewritten to flag the defective track. Writing home addresses is usually done at the IBM plant.

Track Descriptor Record (R0)

This record is always the first record on the track following the home address area. In IBM program- ming systems, the R0 count field of the defective track provides the address of the alternate track. If it is an alternate track, the R0 count area proyides the address of the defective track. An 8-byte data field is used to store the number of bytes remaining on the track.

Specific commands, Write R0 and Read R0, are used 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, as well as track descriptor records, can be formatted with or without keys. Generally, file organization determines whether keys are used.

RECORD OVERFLOW

The record overflow function provides a means of processing logical records that exceed the capacity of a track. When using overflow records, the cylinder boundarv limits the size of the record.

8 IBM 3340144 Reference Manual

Equal length records : 8,535 (track capacity) C + KL + DL (bytes/record)

T r a c k : 8 , 5 3 5 >

where:

track where:

C ( o v e r h e a d / r e c o r d ) : 1 6 7 i f K L : 0

= 2 4 2 i f K L + 0 KL: Key length DL: Data length

The number of records (n/ of different key and data lengths that can be recorded on a track must satisfy the following equation (the standard R0 is already accounted for):

Records n

Ic * KL(i) + DL(i) i : 1

1 6 7 i f K L : 0 242Lt KL + O TRACK CAPACITY

The number of records that can be recorded on a track depends on the record size. The following equation can be used to determine the number of equal length records per track. The home address and standard R0 space and skip defect are taken into consideration.

When R0 is not standard, the following formula should be used:

Records =8,'706 >- [KL(o) + DL(o) + C-4] + Track

n

where:

f, trufil + DL(i) + cl

i : 1

c : 1 6 7 i f K L : 0 c : 2 4 2 i f K L + 0

The tables shown in Figures 7 through l0 give maxi- mum sizes of n equal-length records on a track where n is all possible values. Track, cylinder, and data module capacities are given in both the number of bytes and the number of records.

There are tables for records without keys, and for records with keys. In all tables, overhead for home address and standard record zero (KL : 0, DL : 8) is already accounted for.

C : C _

Formats 9

Track Format

-.-

S D I P A I F I C C I H H I D C B

(syrt.t J oata G3 ( (svste./

/storus.

\ C o n t r o l ) 1'Disk to

]storus.

o'13:lJ"'

I t 0 " " . I

I or""

)

l t

t /

ffi

associated gap.

G 2

f- Ro c.*, I

ry

I

G 2

I n d e x

1 \

L r l

G 2 G 2

I N D E X : I n c l i c a t e s t h e b e g i n n i n g o f e a c h t r a r : k . A l l t r a c k s o n t h e d i s k s u r f a r : e a r e s y n c h r o n i z e d b y I n d e x .

G 1 ( G a p 1 ) : S e p a r a t e s I n d e x a n d H o m e A d d r e s s .

H O M E A D D R E S S

S D ( S k i p D i s p l a c e m e r . r t ) : S t o r a g e c o n t r o l in d i c a t o r s f o r s k i p d i s p l a c e r n e n t r : o n c l i t i o n o f t r a c k .

P A ( P h y s i c a l r \ d c i r e s s ) : S t o r a g e c o n t r o l c h e c k f o r v e r i f i c a t i o n .

Note: Ihe SD artd PA bytes are internal conventiorts involv- ing only the storage control and drive. The function is

transparent to the using systetn.

F ( F l a g ) : D e f i n e s t r a c k c o n d i t i o n a s f o l l o w s : B i t 0 - S k i p D i s p l a c e m e n t

B i t s 1 , 2 , 4 , a n d 5 - - U n u s e d . B i t s 6 a n d 7 0 0 = N o r m a l T r a c k

0 1 = A l t e r n a t e T r a c k

1 0 = I

1 1 | D e f e c t i v e T r a c k

T h e f l a g b y t e r r a y b e t r a n s f e r r e d t o a n d f r o n n th e u s i n g s y s t e m . lt r s ti r e o n l y f l a g b y t e t r a n s f e r r a b l e ,

C C ( C y l i n d e r N u m b e r ) : S p e c i f i e s t h e c y l i n d e r n u m D e r : F o r 3 3 4 8 3 5 0 t o 3 4 7

F o r 3 3 4 8 - 7 0 0 t o 6 9 5

F o r 3 3 4 8 7 O F 0 t o 6 9 5 ( c y l i n d e r s 1 - 5 f i > r e d h e a d s ) H H ( T r a c k N u r r r b e r ) : S p e c i f i e s t h e r e a d l w r i t e tr a c k n u m b e r w i t h t h e s e l e c t e d c y l i n d e r :

F o r 3 3 4 8 - 3 5 0 - 1 1 F o r 3 3 4 8 - 7 0 0 - 1 1

F o r 3 3 4 8 - 7 0 F 0 - 1 1 ( c y l i n d e r s 1 - 5 f i x e d h e a d s ) D C B ( D e t e c t i o n C o d e B y t e s ) : G e n e r a t e d b y t h e 3 3 4 0 - , 4 2 a n d u s e d fo r e r r o r d e t e c t i o n .

l ; i g u r c 6 . R e c o r d a n d T r a c k l r o r n r a t

l0 IBM 3340144 Reference Manual

G 2

t S t a n d a r d R 0 d o e s n o t c o n t a i n a n R 0 k e y a r e a o r

G 2 ( G a p 2 ) : S e p a r a t e s h o m e a d d r e s s a n d R 0 c o u n r a r e a .

R E C O R D Z E R O

R O C O U N T A R E A

S D a n d P A : S a m e a s H o m e A d d r e s s .

F ( F l a g ) : D e f i n e s tr a c k c o n d i t i o n i d e n t i f i e r fo r o v e r f l o w r e c o r o s .

B i t s 0 - 2 * S k i p D i s p l a c e m e n t I n d i c a t o r s . B i t s 3 a n d 5 - U n u s e d , b i t 5 i s a l w a y s z e r o .

B i t 4 - W h e n o n , i n d i c a t e s t h a t a l o g i c a l re c o r d c o n t i n u e s o n t h e n e x t t r a c k .

B i t s 6 a n d 7 - 0 0 = N o r m a l T r a c k 0 1 = A l t e r n a t e T r a c k

1 0 = ) |

i i = l D e f e c t i v e T r a c k

C C ( C y l i n d e r N u m b e r ) : S p e c i f i e s t h e c y l i n d e r n u m b e r :

F o r 3 3 4 8 - 3 5 0 t o 3 4 7 F o r 3 3 4 8 - 7 0 0 t o 6 9 5

F o r 3 3 4 8 - 7 0 F 0 t o 6 9 5 ( c y l i n d e r s 1 - 5 f i x e d h e a d s ) H H ( T r a c k N u m b e r ) : S p e c i f i e s t h e r e a d / w r i t e t r a c k n u m b e r w i t h i n th e s e l e c t e d c v l i n d e r .

F o r 3 3 4 8 - 3 5 0 - 1 1 F o r 3 3 4 8 - 7 0 0 - 1 1

F o r 3 3 4 8 - 7 0 F 0 - 1 1 ( c y l i n d e r s 1 - 5 f i x e d h e a d s ) R ( R e c o r d N u m b e r ) : N o r m a l l y h a s a v a l u e o f H e x 0 0 . K L ( K e y L e n g t h ) : S p e c i f i e s t h e n u m b e r o f b y t e s i n t h e R 0 k e y a r e a , f r o m ' 0 - 2 5 5 b y t e s . F o r s t a n d a r d R 0 . th i s n o r m a l l y h a s a v a l u e o f H e x 0 0 .

D L ( D a t a L e n g t h ) : S p e c i f i e s t h e n u m b e r o f b y t e s i n t h e R 0 data area, from 1 to track capacity. For standard R0, tlris n o r m a l l y h a s a v a l u e o f H e x 0 8 .

DCB (Detection Code Bytes): Generated by the 3340-42 a n d u s e d t o r e r r o r d e t e c t i o n .

Track Format

D i s k t o Storage C o n t r o i D a t a

I ) G 3 )

G 2 ( G a p 2 ) : P r e c e d e s a l l k e y a r e a s . R O K E Y A R E A

K E Y A R E A : l d e n t i f i e s i n f o r m a t i o n i n t h e d a t a a r e a . F o r s t a n d a r d R 0 , t h i s a r e a is n o t p r e s e n t o n t h e t r a c k .

D C B ( D e t e c t i o n C o d e B y t e s ) : l f k e y a r e a is w r i t t e n , t h e s e b y t e s a r e g e n e r a t e d b y t h e 3 3 4 0 - 4 2 a n d u s e d fo r e r r o r detection.

G 2 ( G a p 2 ) : P r e c e d e s a l l d a t a a r e a s . R O D A T A A R E A

D A T A A R E A : C o n t a i n s th e i n f o r m a t i o n i d e n t i f i e d b v t h e c o u n t a n d k e y a r e a s .

D C B ( D e t e c t i o n C o d e B y t e s ) : G e n e r a t e d b y t h e 3 3 4 0 - 4 2 a n d u s e d fo r e r r o r d e t e c t i o n a n d c o r r e c t i o n .

D A T A R E C O R D C O U N T A R E A ( R 1 - - R n ) G 3 ( G a p 3 ) : P r e c e d e s a l l c o u n t a r e a s , e x c e p t R 0 ,

D A T A R E C O R D

D A T A R E C O R D C O U N T A R E A F ( F l a g ) : S a m e a s R e c o r d Z e r o .

C C ( C y l i n d e r N u m b e r ) : S p e c i f i e s t h e c y l i n d e r n u m b e r : For 3348-35 0 to 347

For 3348-70 0 to 695

F o r 3 3 4 8 - 7 0 F 0 t o 6 9 5 ( c y l i n d e r s | - 5 f i x e d h e a d s )

I n d e x

H H ( T r a c k N u m b e r ) : S p e c i f i e s t h e r e a d / w r i t e tr a c k n u m b e r w i t h i n t h e s e l e c t e d c y l i n d e r :

F o r 3 3 4 8 - 3 5 0 - 1 1 F o r 3 3 4 8 - 7 0 0 - 1 1

F o r 3 3 4 8 - 7 0 F 0 - 1 1 ( c y l i n d e r s 1 - 5 f i x e d h e a d s ) R ( R e c o r d N u m b e r ) : S p e c i f i e s t h e s e q u e n t i a l n u m b e r o f t h e r e c o r d o n t h e t r a c k i f s p e c i f i e d b y p r o g r a m m e r . K L ( K e y L e n g t h ) : S p e c i f i e s t h e n u m b e r o f b y t e s i n t h e k e y a r e a , fr o m 0 - 2 5 5 b y t e s .

D L ( D a t a L e n g t h ) : S p e c i f i e s t h e n u m b e r o f b y t e s in t h e d a t a a r e a , fr o m 1 t o t r a c k c a p a c i t y .

D C B ( D e t e c t i o n C o d e B y t e s ) : G e n e r a t e d b y t h e 3 3 4 0 - 4 2 and used for error detection.

G 2 ( G a p 2 ) : P r e c e d e s a l l k e y a r e a s . D A T A R E C O R D K E Y A R E A ( R 1 - R n )

K E Y A R E A : l d e n t i f ie s in f o r m a t i o n i n t h e d , a t a a r e a . D C B ( D e t e c t i o n C o d e B y t e s ) : G e n e r a t e d b y t h e 3 3 4 0 - 4 2 and used for error detection.

G 2 ( G a p 2 ) : P r e c e d e s a l l d a t a a r e a s . D A T A R E C O R D D A T A A R E A ( R 1 - R n )

D A T A A R E A : C o n t a i n s th e i n f o r m a t i o n i d e n t i f i e d b y t h e c o u n t a n d k e y a r e a s .

DCB (Detection Code Bytes): Generated by the 3340-42 and used for error detection and correction.

G 4 { G a p 4 ) : P a d d i n g fr o m e n d o f t h e l a s t d a t a a r e a to Index. lf used for defect skipping, G4 is cent.ered over the defect.

Formats I I

K e y D C B

Record Length Track Capacity Cylinder Capacity ( D L )

(Bytes)

( R e c o r d s ) ( B y t e s ) ( R e c o r d s ) ( B y t e s )

8,368 4 , 1 0 0 2 , 6 7 8 1 , 9 6 6 1 , 5 4 0 1 , 2 5 5 1 , O 5 2

899 7 8 1 686 608 544 489 442 442 366 3 3 5 3 0 7 282 259 239 220 204 1 8 8 1 7 4

t o l

1 4 9 ' t 2 7137 ' t

1 7 1 0 8 99 9 1 84 7 6 70 63 5 7 5 1 4 6 4 1 36 . 3 1

26 2 2 1 8 1 4 1 0 7 3

1 2 4 5

o

ti q

1 0 l 1 1 2

I J

1 4

t c t o

1 7 1 8 ' t 9 20 2 1 2 2 23 24 2 5 2 6 2 7 28 2 9 3 0

J I

3 2

J J

34 3 5 3 6

J I

38 39 4 0 4 1 4 2 4 3 44 4 5 4 6 4 7 48 4 9 50

8 , 3 6 8 8 , 2 0 0 8,034 7,864 7 , 7 0 0 7 , 5 3 0 7,364 7 , 1 9 2 7,O29 6,860 6,688 6,528 6 , 3 5 7 6 , 1 8 8 6,030 5 , 8 5 6 5 , 6 9 5 5,526 5 , 3 5 8 5 , 1 8 0 5 , 0 1 9 4,840 4,692 4 , 5 1 2 4 , 3 5 0 4 , 1 8 6 4,023 3 , 8 3 6 3 , 6 8 3 3 , 5 1 0 3,348 3 , 1 6 8 3 , 0 0 3 2,856 2 , 6 6 0 2,520 2,331 2 , 1 6 6 1 , 9 8 9 1 , 8 4 0 1 , 6 8 i 1 , 5 1 2 1 , 3 3 3 1 , 1 4 4 990 828 6 5 8 480 3 4 3 1 5 0

1 2 24 3 6 4 8 6 0 7 2 84 9 6 1 0 8 120 132 1 4 4 r 5 6 1 6 8 1 8 0 192 204 2 1 6 228 240 2 5 2 264 276 288 300 3 1 2 324 3 3 6 348 3 6 0 3 7 2 384 396 4 0 8 420 432 444 4 5 6 4 6 8 480 492 504 5 1 6 528 540 552 564 576 588 600

1 0 0 , 4 1 6 98,400 96,408 94,368 92,400 90,360 8 8 , 3 6 8 86,304 84,348 82,320 80,256 7 8 , 3 3 6 76,284 74,256 72,360 7 0 , 2 7 2 68,340 66,312 64,296 6 2 , 1 6 0 60,228 58,080 56,304 54,144 52,200 50,232 48,276 46,O32 44,196 4 2 , 1 2 0 4 0 , 1 7 6 3 8 , 0 1 6 36,036 34,272 3 1 , 9 2 0 30,240 2 7 , 9 7 2 25,992 23,868 22,O80 2 0 , ' t 7 2 't8,144 1 5 . 9 9 6 13,728 1 1 , 8 8 0 9,936 7 , 8 9 6 5 , 7 6 0 4 , 1 1 6

1 , 8 0 0

F i g u r c 7 . R c c o r d ( l a p a c i t i e s p e r T r a c k a n d ( ' y l i n d e r - W i t h o u t K e y s

12 IBM 3340/44 Reference Manual

M O D E L 3 5 M O D E L 7 O I 7 O F

Records Bytes Records Bytes

4 , 1 7 6 8 , 3 5 2 12,528 16,704 20,880 25,056 29,232 33,408 3 7 , 5 8 4 4 1 , 7 6 0 4 5 , 9 3 6 5 0 , 1 1 2 54,288 58,464 62,640 6 6 , 8 1 6 70,992 7 5 , 1 6 8 79,344 8 3 , 5 2 0 8 7 , 6 9 6 9 1 , 8 7 2 96,048 100,224 1 0 4 , 4 0 0 1 0 8 , 5 7 6 1 ' t 2 , 7 5 2 1 1 6 , 9 2 8 1 2 1 , 1 0 4 125,280 129,456 1 3 3 , 6 3 2 1 3 7 . 8 0 8 1 4 t ,984 1 4 6 , 1 6 0 1 5 0 , 3 3 6 154,512 1 5 8 . 6 8 8 162,864 167,O40 1 7 1 , 2 1 6 175,392 1 7 9 , 5 6 8 183,744 187,920 1 9 2 , 0 9 6 196,272 200,448 204,624 208,800

34,944,768 34,243,200 33,549,984 32,840,064 32,155,200 31,445,280 30,752,064 3 0 , 0 3 3 , 7 9 2 2 9 . 3 5 3 , 1 0 4 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 2 1 , 6 3 1 , 6 8 0 20,959,344 20,211,840 19,593,792 18,842,112 1 8 . 1 6 5 , 6 0 0 17,480,736 1 6 , 8 0 0 , 0 4 8 1 6 , 0 1 9 , 1 3 6 1 5 , 3 8 0 , 2 0 8 14,657,760 13,981,248 13,229,568 12,540,528 1 1 , 9 2 6 , 6 5 6 1 1 ,1 0 8 , 1 6 0 1 0 , 5 2 3 , 5 2 0

9,734,256 9,O45,216 8,306,064 7 , 6 8 3 , 8 4 0 7 , 0 1 9 , 8 5 6 6 , 3 1 4 , 1 1 2 5,566,608 4 , 7 7 7 , 3 4 4 4,134,240 3,457,728 2,747,808 2,OO4,480 1,432,368

626,400

8 , 3 5 2 16,704 25,056 33,408 4 1 , 7 6 0 5 0 , 1 1 2 58,464 6 6 , 8 1 6 7 5 , ' t 6 8 83,520 9 1 , 8 7 2 100,224 1 0 8 , 5 7 6 1 1 6 , 9 2 8 125,280 1 3 3 , 6 3 2 141,984 1 5 0 , 3 3 6 1 5 8 , 6 8 8 167,O40 175,392 183,744 ' t 9 2 , 0 9 6 200,448 208,800 2 1 7 , 1 5 2 225,504 2 3 3 , 8 5 6 242,208 2 5 0 , 5 6 0 258,912 267,264 2 7 5 , 6 1 6 2 8 3 , 9 6 8 292,320 300,672 309,024 3 ' , t 1 , 3 7 6 325,728 334,080 342,432 3 5 0 , 7 8 4 3 5 9 , 1 3 6 3 6 7 , 4 8 8 3 7 5 , 8 4 0 384,192 392,544 400,896 409,248 4 ' t 7 , 6 0 0

69,889,536 68.486,400 67,099,968 6 5 , 6 8 0 , 1 2 8 6 4 , 3 1 0 , 4 0 0 62,890,560 61,504,128 60,067,584 58,706,208 57,294,720 5 5 . 8 5 8 , 1 7 6 5 4 , 5 2 1 , 8 5 6 5 3 , 0 9 3 , 6 6 4 51,682,176 5 0 , 3 6 2 , 5 6 0 4 8 , 9 0 9 . 3 1 2 47,564,640 46,153,152 44,750,O16 4 3 , 2 6 3 , 3 6 0 4 1 , 9 1 8 , 6 8 8 40,423,680 3 9 , 1 8 7 , 5 8 4 37,684,224 3 6 , 3 3 1 , 2 0 0 34,961,472 33,600,096 32,038,272 3 0 , 7 6 0 , 4 1 6 29,315,520 27,962,496 26,459,136 2 5 , 0 8 1 , 0 5 6 23,853,312 22,216,320 2 1 , 0 4 7 , O 4 0

19,468,512 1 8 , 0 9 0 , 4 3 2 16,612,128 1 5 , 3 6 7 , 6 8 0 1 4 , O 3 9 , 7 1 2 1 2 , 6 2 8 , 2 2 4 1 1 , 1 3 3 , 2 1 6 9 , 5 5 4 , 6 8 8 8 , 2 6 8 , 4 8 0 6 , 9 1 5 , 4 5 6 5 , 4 9 5 , 6 1 6 4,008,960 2,864,736 1 , 2 5 2 , 8 0 0

F i g u r c 8 . R e c o r d C a p a c i t i e s p e r D a t a M o d u l e - W i t h o u t K e y s

F o r m a t s l 3

Record Length Track Capacity C y l i n d e r C a p a c i t y ( K L + D L )

(Bytes)

( R e c o r d s ) ( B y t e s ) ( R e c o r d s l ( B y t e s ) 8 , 2 9 3

4,O25 2 , 6 0 3 1 , 8 9 1 1 , 4 6 5 ' t , 1 8 0

977 824 706 6 1 1 533 4 6 9 4 1 4 3 6 7 3 2 7 291 260 232 207 184 164 145 129 1 1 3

9 9 86 7 4 6 2 5 2 4 2 3 3 24' 1 6

1 2 3 4 5

o

7 8 9 1 0 1 ' , | 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 24 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2

J J

3 4

8,293 8,050 7 , 8 0 9 7,564 7,325 7.080 6,839 6,592 6 , 3 5 4 6 , 1 1 0 5,863 5,628 5,382 5 , 1 3 8 4,905 4 , 6 5 6 4,420 4 , 1 7 6 3 , 9 3 3 3,680 3 , 4 4 4 3 , 1 9 0 2,967 2 , 7 1 2 2 , 4 7 5 2,236 1 , 9 9 8 1 , 7 3 6 1 , 5 0 8 1 , 2 6 0 1 , 0 2 3 768 528 306

1 2 24 36 4 8 60 7 2 84 96 1 0 8 120 132 1 4 4 1 5 6 1 6 8 1 8 0 192 204 2 1 6 228 240 2 5 2 264 2 7 6 288 300 3 1 2 324 3 3 6 348 360 3 7 2 384 3 9 6 408

9 9 , 5 1 6 9 6 , 6 0 0 9 3 , 7 0 8 9 0 , 7 6 8 8 7 , 9 0 0 84,960 8 2 , 0 6 8 7 9 , 1 0 4 76,248 73,320 7 0 , 3 5 6 6 7 , 5 3 6 64,584 6 1 , 6 5 6 58,860 55,872 53,040 5 0 , 1 1 2 4 7 , 1 9 6 44,160 41,328 3 8 , 2 8 0 35,604 32,544 29,700 26,832 23,976 20,832 1 8 , 0 9 6 15,120 12,276 9 , 2 1 6 6 , 3 3 6 3 . 6 7 2

F i g u r c 9 . R e c o r d C a p a c i t i e s p c r T r a c k a n d C y l i n d e r - W i t h Keys

14 IBM 3340144 Reference Manual

M O D E L 3 5 M O D E L 7 0 / 7 O F

Records Bytes Records Bytes

4 , 1 7 6 8 , 3 5 2 12,528 16,704 20,880 2 5 , 0 5 6 29,232 3 3 , 4 0 8 37,584 4 ' , t , 7 6 0 4 5 , 9 3 6 5 0 , 1 1 2 54,288 5 8 , 4 6 4 62,640

o o , b t b

70,992 7 5 , 1 6 8 79,344 8 3 , 5 2 0 8 7 , 6 9 6 9 1 , 8 7 2 9 6 , 0 4 8 100,224 1 0 4 , 4 0 0 1 0 8 , 5 7 6 1 1 2 , 7 5 2 1 1 6 , 9 2 8 1 2 1 , 1 0 4 125,280 129,456 1 3 3 , 6 3 2 1 3 7 , 8 0 8 1 4 1 , 9 8 4

3 4 , 6 3 1 , 5 6 8 3 3 , 6 1 6 , 8 0 0 3 2 , 6 1 0 , 3 8 4 31,587,264 3 0 , 5 8 9 , 2 0 0 2 9 , 5 6 6 , 0 8 0 2 8 , 5 5 9 , 6 6 4 27,528,192 26,534,304 2 5 , 5 1 5 , 3 6 0 24,483,888 23,502,528 2 2 , 4 7 5 , 2 3 2 21,456,288 20,483,280 19,443,456 18,457,920 17,438,976 16,424,208 1 5 , 3 6 7 , 6 8 0 1 4 , 3 8 2 , 1 4 4 't3,321,440 12,390,192 1 1 , 3 2 5 , 3 1 2 1 0 , 3 3 5 , 6 0 0

9 , 3 3 7 , 5 3 6 8 , 3 4 3 , 6 4 8 7,249,536 6,297,408 5 , 2 6 1 , 7 6 0 4 , 2 7 2 , 0 4 8 3 , 2 0 7 , 1 6 8 2,204,928 1 , 2 7 7 , 8 5 6

8,352 16,704 2 5 , 0 5 6 3 3 , 4 0 8 4 1 , 7 6 0 5 0 , 1 1 2 58,464 6 6 , 8 1 6 7 5 , 1 6 8 8 3 , 5 2 0 9 1 , 8 7 2 100,224 1 0 8 , 5 7 6 116,928 125,280 1 3 3 , 6 3 2 1 4 1 , 9 8 4 1 5 0 , 3 3 6 1 5 8 , 6 8 8 167,O40 175,392 183,7 44 r 9 2 , 0 9 6 200,448 208,800 2 1 7 , 1 5 2 225,504 2 3 3 , 8 5 6 242,208 2 5 0 , 5 6 0 258,912 2 6 7 , 2 6 4 2 7 5 , 6 1 6 2 8 3 , 9 6 8

6 9 , 2 6 3 , 1 3 6 6 7 , 2 3 3 , 6 0 0 65,220,768 63,174,528 6 1 , 1 7 8 , 4 0 0 5 9 , 1 3 2 , 1 6 0 5 7 , 1 1 9 , 3 2 8 5 5 , 0 5 6 , 3 8 4 5 3 , 0 6 8 , 6 0 8 51,O30,120 4 8 , 5 6 t , 1 7 6 4 7 , 0 0 5 , 0 5 6 44,950,464 4 2 , 9 1 2 , 5 7 6 4 0 , 9 6 6 , 5 6 0 3 8 , 8 8 6 , 9 1 2 3 6 , 9 1 5 , 8 4 0 34,877,952 32,848,416 3 0 , 7 3 5 , 3 6 0 28,764,288 26,642,880 24,780,384 22,650,624 20,671,200 1 8 , 6 7 5 , 0 7 2 16,681 ,296 1 4 , 4 9 9 , 0 7 2 1 2 , 5 9 4 , 8 1 6 10,523,520

8 , 5 4 4 , 0 9 6 6 , 4 1 4 , 3 3 6 4 , 4 0 9 , 8 5 6 2 , 5 5 5 , 7 1 2

I i g u r c 1 0 . R c c o r d ( ' u p a c i t i c s p e r l ) a t a M o d r r l c W i t l t K e 1 , s

F o r m a t s l 5

INPUT/ OUTPUT OPERATIONS

This section contains a general description of l/ O operations used with IBM disk storage devices.

Detailed information about the central processing unit and channel program control of I/O operations is foundin IBM System/370 Principles o,f Operation, Order No. GA22-7000.

DEVICE SELECTION AND ADDRESSING Device Address

3 3 4 0 D R I V E S

Drive addresses are specified in the I/O instruction.

The 3340 address is specified in bits 4, 5.,6, and 7 of the address byte (byte 3); bit 3 is also used with 32 drive addressing.

Any drive address from hex 0 to F can be accepted.

Drives 0 to 7 are attached to the first con.troller string and drives 8 to F on the second string. If a logical connection cannot be made because the required drive is offline, Unit Check (Intervention Required) is returned. If multiple selection is detectecl because of a hardware failure, Unit Check (Intervention Required) is returned.

Note: Ifte drive addresses must be wired on a logic board in the drive units.

3 3 4 4 D R I V E S

For configurations r"rsing 3344 drives, lhe device addressing is modified to handle the multiple logical devices on each spindle. Bits 2 througJr 7 of byte 3 specify the logical device (a maximum of 64) and bits 0 and I the storage control address. This

addressing allows 3344 drives on strings 0 and 2 only.

String 3 can have only two 3340 units., one A2 and one B (see Figure 3). When 3344 drives are attached

to a storage control, only 334013344 clevices can be controlled; 3330 or 3350 strings cannot be attached.

Seek Address

A specific track is selected by sending the seek address and a Seek command to the required drive. These and other commands are described in the ISC and 3830-2 reference manuals.

Bytes 0 and I are unused, bytes 2 and 3 ilre the logical cylinder address, and bytes 4 and 5 are the logical track address. All seek addresses consist of six bvtes.

0 1 2 3 4 5

O O C C H H

The CCHH part of count areas and home addresses normally corresponds to bytes 2 through 5 of the seek address. The physical address (PA) bytes in each count area and home address indicate physical cylinder and track addresses. The PA bytes are written by the storage control and are used for seek verification.

When the seek argument is received by the storage control, it is converted into physical cylinder and track addresses and sent to the selected drive for Seek operations. The acceptable seek addresses for the 3340/3344 devices are:

ACCESS AND DATA TRANSFER SPEED

The total time required for access and data transfer consists of access motion, head selection, rotational delay, and data transfer.

Access Motion Time

Access motion 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. Access time is also zero for data stored under fixed heads when fixed head models are used.

If the access mechanism must move to another cylin- der, a minimum of 10 milliseconds is required. The maximum access movement is 50 milliseconds. but the average access time is 25 milliseconds.

Head Selection Time

The time required to select the read/write head is negligible.

Storage Model

Data Tracks Alternate Tracks

cc

^{H H}

cc

^{H H}

3348-35 a - 3 4 7

0 - ' 1 1 348 0 - 1 1

3 3 4 8 - 7 0

3 3 4 8 - 7 0 F

0 - 6 9 5 0 - 1 1 6 9 6 , 6 9 7

0 -

1 1

3344-82

3344.82F

0 - 6 9 5

x4

0 - 1 1 6 9 6 , 6 9 7

x 4

0 - 1 1

l6 IBM 3340144 Reference Manual

Rotational Delay

Rotational delay is the time required for the desired record area to reach the read/write head so that data transfer can begin. This time can range from zero to almost a full revolution. Half a revolution (average rotational delay) is generally used for timing purposes.

The maximum and average rotational delays for 3340 / 3344 drives are:

Maximum rotational delay : 20.24 milliseconds Average rotational delay : 10.12 milliseconds Note: Use of the Rotational Position Sensing featire minimizes the effect of rotational delay by permitting the drive to disconnect from the channel,

thereby allowing use of other drives during a latency period.

Data Transfer

Nominal read/write rates for the disk drives are:

Bytes-per-second : 885,000 Microseconds-per-byte = 1.13 DATA SECURITY AND PRIVACY

The 3340 and 3344 have a Read Only function. This function, in conjunction with previous methods such as File Protect and Seek Verification, offer a means of limiting access to data areas of the data module.

Read Only Function

3340 MODELS

The Read Only function provides the means for protecting designated data modules from being rewritten or erased.

Each data module is equipped with an inset in the handle. The operator can change the inset position before inserting the data module in the drive.

Note: Iftis insert is only accessible when the data module is not on the drive (see the "Operating Instructions" sect ion).

When the Read Only option is made, any Write command addressed to the drive is rejected. Subse- quent sense Lnformation indicates Command Reject (byte 0, bit 0) and Write Protect (byte 1, bit 6).

3 3 4 4 M O D E L S

In the 3344 dual-drive models, the Read Only func- tion is controlled by a switch on the operator panel for each drive.

File Protection

Control of Write and Seek commands within a pro- gram can be affected by the Set File Mask command.

A description of the Set File Mask command is given in the ISC and 3830-2 reference manuals.

By entering a Set File Mask, selected Write and Seek commands can be inhibited even though they appear in the command chain.

Seek Verification

The 334O/3344 track format includes two bytes in each count area and home address (physical address, PA) for seek verification. When a count area or home address is processed during Read, Search, or Clock operations, the bytes are compared with the most recent seek address. A non-compare results in termi- nation of the operation at the end of the count area or home address with channel end, device end, and unit check. Seek check is also indicated in the sense information.

Input/OutputOperations 17

ERROR RECOVERY PROCEDURE

Error handling usually involves storage control and system-invoked recovery actions. These recovery actions can vary depending on how and to what system the 3340/3344 is attached.

The following topics are associated with recovery actions involving the 3830 Model2, or ISC (storage controls), and the 3340/3344:

o Error Correction Function o Error Condition Table o Errory Recovery Action

ERROR CORRECTION FUNCTION

The error correction function (ECF) is part of the recovery action procedure. The ECF algorithms and the related procedure are fully described in the 3830 Model 2 and ISC reference manuals.

ERROR CONDITION TABLE

The Error Condition Table (Figure l1) identifies unique configurations of sense bits set by the storage control in sense bytes 0, 1, and 2. In addition, it refers to each of these configurations in a specific reco,yery action to be invoked by the system.

ERROR RECOVERY ACTION

The 3340/3344 Recovery Action Table (Figure 12) specifies actions to be taken for error conditions listed in the Error Condition Table. A necessary part of the recovery action is the construction of Restart Channel Command Words 1 and 2.

Construction of Restart CCWs

If Operation Incomplete (byte 1, bit 7) is set in the sense information. it indicates that an error or unusual condition occurred during a logical operation after data transfer had been initiated. By constructing Restart Channel Command Words, the e,rror recovery procedures can correct the unusual condition and continue the operation in progress from the point of interruption to the normal ending point.

RESTART CCW I

Restart CCW 1 is constructed as follows:

l. The command code byte is provided in sense byte 3.

2. The data address is that of the interrupted CCW, plus the count of that CCW, minus the residual count in the channel status word (CSW).

3. The flags, except Program Controlled Interrupt (PCI), are those of the interrupted CCW.

4. The count is the residual count in the CSW. If the residual count is zero, a count of one must be used. If a Write command is in progress, the data address should specify a byte containing '00' . If a Read command is in progress, turn on the skip bit.

RESTART CCW 2

Restart CCW 2 is constructed as follows:

l. The command code is provided in sense byte 3.

2. The count is constructed as follows:

a. Fetch the count of the CCW designated by CSW-8, and set a pointer to this CCW.

b. Subtract the restart displacement from the count obtained in step a. If this result is positive, go to step f; otherwise go to step c.

c. Check the chain data flag of the CCW desig- nated by the pointer. If the flag is not set, go to step e; otherwise go to step d.

d. Advance the pointer to the next non-Transfer in Channel (non-TIC) CCW in the data chain and add the count of this CCW to the counts of all preceding non-TIC CCWs in the data chain. Return to step b.

e. Truncation occurs. Set the restart CCW 2 count equal to 1. Go to step 3 and include the skip bit in the Restart CCW flags.

f. Set the Restart CCW 2 count equal to the result of the subtraction in step b.

Go to Step 3.

l8 IBM 3340144 Reference Manual

3 .

4 .

The flags (except PCI) are those of the CCW designated by the pointer in Step 2. The skip bit is also set if Step 2e was previously executed.

The data address is that of the CCW designated by the pointer in Step 2, plus the count of that CCW, minus the Restart CCW count generated in Step 2.

If another Operation Incomplete occurs while execut- ing the Restart CCW, a new Restart CCW may be generated from the old Restart CCW.

Note: Be sure to avoid destroying the old Restart CCW before generating the new one.

Error Recovery Procedure 19