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a o a a a a a a a a a a a a a a a a a a o a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a o a a a a a a a a a a a a
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a a a a a a a a a a a a a a a o a a
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P r o g r a m P l a n n i n g M a n u a l
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GC21-5040-3 File No. 53-05
P a g e o f G C 2 1 - 5 O 4 0 - 3 l s s u e d 3 0 J u n e 1 9 7 8 B y T N L : G N 2 1 " 5 6 0 4
Fourth Edition (March 19761
T h i s i s a m a j o r r e v i s i o n of , and obsoretes, G C 2 r - b 0 4 0 - 2 . T h i s rnanuar has been changeo t o a n c l u d e t h e M o d e i B a n d the Model 12. Changes a r e i n d i c a t e d b y a v e r . t i c a l l i n e a t t h e l e f t o f t i r e c h a n g e ; n e w or extensivery revised iilustrations are denoted by a builet oat t h e l e f t t ) f t h e f i g u r e caption.
c h a n g e s a r e p e r i o d i c a l l y made to the in{ormation herein; before using this pubrication I n c o n n e c t i o n w i t h thc operation .r rBM systems, retef to the ratest tgM system/3 Bibliography, Gc20-8080 f or the editi'ns that are appricabre and current.
U s e th i s p u b l l c a t i o n c n l y f o r the pul poses staled in the preface.
P u b l i c a t i o n s a r e n o t s t o c k e d a t t h e a d d r e s s b e l o w . R e q u e s t s f o r c o p i e s o f I B M p u b l i c a t i o n s a n d f o r t L e c h n i c a l i n f o r m a t i o n a b o u t t h e s y s t e m should be made tc) your l6M representative o r t o t h e I B M b r a n c h o f f i c e serving your iur:alitv,
T h i s p r L r l i c a t i o n c o u l d c o n t a i n t e c h n i c a l in a c c , . L : " a c i e s o r t y p o g r a p h i c a l e r r o r s . u s e t h e R e a d e r ' s c o m m e n t F o r m a t t h e b a c k oi this pub!ii:ation to make co.rnments a b o u t t h i s p u b i i c a t i o n . lf the form has beerr rernoved, address Vr:ur comments to iBM Corporation, P u b l i c a t i o n s , D e p a r t m e n t 2 4 5 , R o c h e s t e r ' , f i 4 i r n e s o r , a 5 F 9 0 1 . c o m m e n t s b e c o n r e the p r o p e r t y ' o f lB M .
O C o p y r i g h t l n t e r n a t i o n a l B u s i n e s s M a c h i n e s C o r p o r a t i o n 1 g 7 1 . 1 g - 1 4 . 1 g 7 6
This manual introduces you to the 3410/341 1 Magnetic T a p e S u b s y s t e m f o r t h e I B M S y s t e m / 3 . T h i s m a n u a l w i l l help installation managers decide if they want to use mag- netic tape and aid in evaluating the effect that it will have on their current operations. Information contained in the m a n u a l w i l l a i d in p l a n n i n g f o r t h e u s e o f m a g n e t i c t a p e . The manual contains:
A description of magnetic tape
A description of the organizations of tape files A description of tape labels
A description of control statement requirements A description of the Tape Initialization program A description of the functions supported by RPG ll, C O B O L , F O R T R A N lV , B a s i c A s s e m b l e r , D i s k S o r t , Magnetic Character Reader Utility. and Tape Sort program products
The reader should be familiar with the operation and programming concepts of the System/3.
A glossary is provided at the back of this manual to def ine important terms.
Page of GC21-5040-3 lssued 30 June 1 978 B y T N L : G N 2 1 - 5 6 0 4
Preface
Page of GC21-5040-3 lssued 30 June 1978 By TNL: GN21-5604
Related Publications
Order Number of Publication for System/3
M o d e l 1 0 Card System
System/3 Model 8
System/3 Model 10 Disk System
System/3 M o d e l 1 2
System/3 M o d e l 1 5
O p e r a t o r ' s G u i d e GC21.75'13 GC21-7634 i:ii::!:!it!iiiiiiitiitiii!:ii:i::i::i::i::ii:ii.ii:ii,i:,ii,:,i,:ii:i,:,i:i:::i::i::i:::i::iiii:it::i::i::i::i::i:iii;i:i:iiiiii::li:i:ii:i:
R P G ll R e f e r e n c e
M a n u a l
s c 2 1 - 7 5 0 0 s c 2 1 - 7 5 0 4
System Control P r o g r a m m i n g R e f e r e n c e M a n u a l
GC21-7512 G C 2 1 - 5 1 3 0
GC21-5077r GC21-51622
H a l t G u i d e
(System Messages) GC21-7540 G C 2 1 - 5 1 4 5 G C 2 1 . 5 0 7 6
System Control P r o g r a m m i n g M a c r o s Reference Manual
GC21-7562 G C 2 1 - 7 6 0 8
U s e r ' s G u i d e .iiiiiiiijiiiiiiiiiiitit]:.iix.itiiitiiiiiiiiiiii1111111.rrri.
'... r...,...,...11iii:ii1it1
GC21-5142 Disk Concepts and
P l a n n i n g G u i d e
GC21.7571
S u b s e t A m e r i c a n N a t i o n a l S t a n d a r d C O B O L R e f e r e n c e M a n u a l
GC28-6452
F O R T R A N I V R e f e r e n c e M a n u a l
sc28-6874
B a s i c A s s e m b l e r
R e f e r e n c e M a n u a l
s c 2 1 - 7 5 0 9
D i s k S o r t
R e f e r e n c e M a n u a l
iiiiiiili:fi:i:r::
::::::::::::.:.:.:.:.:.::::::::::::
:::::::::::::::::.:!i.::: :.: :::.:
sc21-7522
Tape Sort
R e f e r e n c e M a n u a l
sc21-7572
Components
R e f e r e n c e M a n u a l G A 2 1 . 9 2 3 6
l Models 15A. B, c 2 Model 15D
Contents
C H A P T E R 1 . I N T R O D U C T I O N A d v a n t a g e s o f a T a P e S Y s t e m
C H A P T E R 2 . M A G N E T I C T A P E C O N C E P T S R e c o r d i n g D a t a o n M a g n e t i c T a P e
F i l e P r o t e c t i o n
I n t e r s y s t e m T a p e E x c h a n g e T a p e F i l e F o r m a t s T a p e L a b e l s
E x t e r n a l L a b e l s
C H A P T E R 5 . SUBSYSTEM
3 4 1 0 1 3 4 1 1 M A G N E T I C T A P E S o e c i a l F e a t u r e s .
S i n g l e D e n s i t y T a P e U n i t F e a t u r e . D u a l D e n s i t v T a P e U n i t F e a t u r e S e v e n - T r a c k T a P e U n i t F e a t u r e D u a l D e n s i t y C o n t r o l F e a t u r e S e v e n - T r a c k C o n t r o l F e a t u r e
A P P E N D I X A . T A P E L A B E L F O R M A T S V o l u m e L a b e l F o r m a t
H e a d e r L a b e l 1 a n d T r a i l e r L a b e l 1 F o r m a l H e a d e r L a b e l 2 a n d T r a i l e r L a b e l 2 F o r m a t G L O S S A R Y
I N D E X 1
z 2 5
25
z o z b
26 26 26 27 2 A 2 9 3 1 32 l n t e r n a l L a b e l s
T a o e R e c o r d A t t r i b u t e s F i x e d L e n g t h R e c o r d s V a r i a b l e L e n g t h R e c o r d s T a p e B l o c k i n g F a c t o r s T a p e C t r a r a c t e r C o d e s
3
J
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2
J
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6 6 7 1 1 A S C I I F i l e s
E B C D I C F i l e s
I U
8 , 1 0 , 1 2 a n d 1 5
C H A P T E R 3 . M A G N E T I C T A P E S Y S T E M S U P P O R T C o n t r o l S t a t e m e n t R e q u i r e m e n t s
M o c i e l 1 0 C a r d S y s t e m
M o d e l 8 . M o d e l 1 0 D i s k S y s t e m , M o d e l 1 2 , a n d M o d e l 1 5
K e y w o r d P a r a m e t e r s f o r t h e F I L E S t a t e m e n t 9
T a p e D a t a M a n a g e m e n t 1 3
E n d o f V o l u m e P r o c e s s i n g 1 3
D u a l P r o g r a m m i n g ( M o d e l s 8 , 1 0 , a n d 1 2 ) o r
M u l t i p r o g r a m m i n g ( M o d e l 1 5 ) 1 3 M a g n e t i c T a p e U t i l i t y P r o g r a m s 1 4
T a p e I n i t i a l i z a t i o n P r o g r a m 1 4
C o n t r o l S t a t e m e n t s 1 4
C H A P T E R 4 . M A G N E T T C T A P E P R O G R A M P R O D U C T 8 8
6
S U P P O R T
C a r d R P G l l f o r M o d e l D i s k R F G l l f o r M o d e l s S u b s e t A N S C O B O L F O R T F A N I V
M a g n e t i c C h a r a c t e r R e a d e r U t i l i t y P r o g r a m T a p e S o r t P r o g r a m
S y s l e m R e q u i r e m e n t s T a p e S o r t F i l e s S o r l F u n c t i o n s R e c o r d S e l e c t i o n F i e l d S e l e c t i o n A c l c l i t i o n a l F e a t u r e s . B a s i c A s s e m b l e r D i s k S o r t P r o g r a m
S p e c i a l C o n s i d e r a t i o n s f o r V a r i a b l e L e n g t h R e c o r d s M a g n e t i c T a p e S u P P o r t S u m m a r Y
1 7 1 8 1 8 1 9
1 0
' 1 9 1 9 1 9 2 0 2 0 20 20 22 2 2 2 2
Z J
The IBM 3410/3411 Magnetic Tape Subsystem (Models 1, 2. and 3) reads and writes half-inch, 7- or 9-track magnetic tape. The subsystem provides an economical approach for increasing the storage capacity of the IBM System/3. (Seven- track magnetic tape is not available for the Model 10 Card System. )
System/3 supports a maximum of four tape units. The 3 4 1 1 is r e q u i r e d . U p t o t h r e e 3 4 1 0 s c a n b e a t t a c h e d v i a the 34'11 provided the 3410s are the same model as the
u l 1 .
Chapter 1. Introduction
341 1 Magnetic Tape Unit and Control
3 4 1 0
Magnetic Tape U n i t341 0 M a g n e t i c Tape U n i t
3 4 1 0
Magnetic Tape U n i tI n t r o d u c t i o n 1
Page of GC21-5040-3 lssued 30 June 1978 By TNL: cN2l-5604
ADVANTAGES OF A TAPE SYSTEM
Compared with cards or diskettes, records on tape may be any size (within limits) depending on the storage capacity of the processing unit and the program products for the system (see Magnetic Tape Support Summary for allowable record lengths). This allows writing pertinent information in a continuous data record. Repeating the identification in multiple records is eliminated.
Magnetic tape records, like disk records, are permanenr.
However, during a tape write operation, the previously recorded information is erased. This means that tape may be used again and again with a significant cost saving over the use of cards. Diskettes are also reusable.
There are other advantages in using magnetic tape:
Large amounts of data can be stored economically.
With appropriate spacing between groups of records, approximately 112 boxes of System/3 96-column cards can be stored on a 2400-foot reel of tape.
History files can be retained indefinitely.
A duplicate of disk pack records can be kept.
Information can be transferred easily to other data processing locations.
System/3 magnetic tape is compatible with magnetic tape for other systems.
R E C O R D I N G D A T A O N M A G N E T I C T A P E
Data is recorded by moving tape across a read/write head.
I t i s w r i t t e n w h i l e t h e t a p e i s m o v i n g f o r w a r d b u t m a y b e r e a d e i t h e r f o r w a r d o r b a c k w a r d . D a t a i s w r i t t e n a s a series o f m a g r r e t i z e d b i t s i n p a r a l l e l t r a c k s a l o n g th e l e n g t h o f t h e t a p e .
T h e r e c o r d i n g d e n s i t y i s t h e n u m b e r o f b i t s i n a s i n g l e l i n e a r tr a c k m e a s u r e d p e r u n i t l e n g t h o f t a p e . F o r 9 - t r a c k t a p e , t h e 3 4 1 0 / 3 4 1 1 M a g n e t i c T a p e S u b s y s t e m r e c o r d s in d e n s i t i e r s o f 8 0 0 o r 1 6 0 0 b p i ( b i t s o r b y t e s p e r i n c h ) . A d u a l d e n s i t y f e a t u r e is a v a i l a b l e t h a t p e r m i t s o p e r a t i o n a t e i t h e r € i 0 0 o r 1 6 0 0 b p i . F o r 7 - t r a c k t a p e , d e n s i t i e s c a n b e 2 0 0 , 5 5 6 , o r 8 0 0 b p i .
F I L E P R O T E C T I O N
T h e 3 4 1 0 / 3 4 1 1 u s e s a p l a s t i c w r i t e - e n a b l e r i n g m o u n t e d o n t h e t a p e r e e l to p e r m i t w r i t i n g . l f a t a p e i s m o u n t e d w i t h o u t t h e r i n g l i n p o s i t i o n , w r i t i n g c a n n o t o c c u r ; th e r e f o r e , th e f i l e i s p r o t e c t e d .
I N T E R S Y S T E M T A P E E X C H A N G E
T a p e s p r o d u c e d o n t h e 3 4 1 0 1 3 4 1 1 a n d a l l o t h e r I B M h a l f - i n c h t a p e u n i t s o p e r a t i n g in t h e s a m e d e n s i t y a r e i n t e r - , c h a n g e ; r b l e ; o u t p u t d a t a p r o d u c e d o n o n e s y s t e m , s u c h a s I the System /37O, can be used as direct input to another
system, such as System/3.
T A P E F I L E F O R M A T S
Three t'ypes of file formats can be used with the magnetic tape subsystem:
o S i n g l l e f i l e o n a s i n g l e v o l u m e ( r e e l )
| . S i n g l e f i l e o n s e v e r a l v o l u m e s ( m u l t i v o l u m e fi l e ) o S e v e r a l f i l e s o n o n e o r m o r e v o l u m e s o n t h e M o d e l 1 b
I
I ( m u l t i f i l e v o l u m e )
P a g e o f G C 2 1 - 5 0 4 0 - 3 l s s u e d 3 0 J u n e 1 9 7 8 B v T N L : c N 2 1 - 5 6 0 4
Chapter 2. Magnetic Tape Concepts
T h e f o r m a t s o f t h e l a b e l e d f i l e s a r e s h o w n i n F i g u r e s 1 a n d 2 ; t h e f o r m a t s o f t h e u n l a b e l e d f i l e s a r e s h o w n i n F i q u r e s 3 a n d 4 .
T h e l a b e l s o f e a c h r e e l o f a m u l t i v o l u m e fi l e m u s t o e c o n s i s t e n t . T h a t i s , a l l v o l u m e s o f a l a b e l e d m u l t i v o l u m e f i l e m u s t b e l a b e l e d , a n d a l i v o l u m e s o f a n u n l a b e l e d m u l t i v o l u m e fi l e m u s t b e u n l a b e l e d .
M u l t i v o l u m e ta p e f i l e s c a n n o t b e s p e c i f i e d o n t h e M o d e l 8 , M o d e l 1 0 D i s k S y s t e m , o r M o d e l 1 2 f o r p r o g r a m s t h a t a l s o u s e th e B S C A o r d e v i c e s a t t a c h e d to t h e S I O C .
S i m i l a r l y , f i l e s in a m u l t i f i l e v o l u m e m u s t b e c o n s i s t e n t . T h a t i s , a l l f i l e s o n t h e v o l u m e m u s t b e l a b e l e d o r a l l m u s t b e u n l a b e l e d . S e e th e s y s t e m c o n t r o l p r o g r a m m i n g r e f e r e n c e manual for Model 15 listed in the Preface for more
i n f o r m a t i o n o n m u l t i f i l e t a p e v o l u m e s .
T A P E L A B E L S
S y s t e m / 3 fo l l o w s e i t h e r t h e A m e r i c a n N a t i o n a l S t a n d a r d s I n s t i t u t e ( A N S I ) f o r m a g n e t i c t a p e l a b e l s o r IB M M a g n e t i c T a p e L a b e l S t a n d a r d s . T h i s p r o v i d e s c o m p a t i b i l i t y w i t h o t h e r s y s t e m s t h a t u s e e i t h e r A N S I o r t h e I B M M a g n e t i c T a p e L a b e l S t a n d a r d s .
External Labels
You can attach external labels to the outside of taoe reels f o r i d e n t i f i c a t i o n . T h e s e la b e l s s h o u l d i n c l u d e th e r e e l ( o r v o l u m e ) s e r i a l n u m b e r , n a m e o f t h e f i l e , f i l e n u m b e r , d a t e t h e f i l e w a s c r e a t e d , n u m b e r o f t h e v o l u m e ( i f a m u l t i - v o l u m e f i l e ) . a n d o t h e r i n f o r m a t i o n r e q u i r e d fo r i n s t a l l a t i o n .
I n t e r n a l L a b e l s
T h e i n t e r n a l la b e l s , v o l u m e a n d f i l e , a r e w r i t t e n o n t a p e t o p r o v i d e a p r o g r a m m e d id e n t i f i c a t i o n o f t h e f i l e . F i l e l a b e l s p r o v i d e a s a f e g u a r d a g a i n s t m i s h a n d l i n g f i l e s . L a b e l s a r e c h e c k e d b y t a p e d a t a m a n a g e m e n t t o d e t e r m i n e w h e t h e r t h e r e e l c o n t a i n i n g th e d e s i r e d f i l e h a s b e e n m o u n t e d b e f o r e a n y p r o c e s s i n g o c c u r s . T h u s , f i l e l a b e l s e n s u r e t h a t the correct reel is used for input, and that no current data is destroyed on output.
M a g n e t i c T a p e C o n c e p t s 3
P a g e o f G C 2 1 - 5 O 4 O - 3 l s s u e d 3 0 J u n e 1 9 7 8 B y T N L : G N 2 1 - 5 6 0 4
V o l u m e l a b e l s f o r l a b e l e d t a p e s a r e w r i t t e n b y t h e S y s t e m / 3 T a p e I n i t i a l i z a t i o n p r o g r a m a t t h e t i m e a r e e l is p r e p a r e d f o r u s e . T h e v o l u m e l a b e l id e n t i f ie s th e r e e l a n d i s a l w a y s th e first record in a reel. The information contained in the v o l u m e l a b e l is c h e c k e d b y t a p e d a t a m a n a g e m e n t a n d n e v e r a l t e r e d d u r i n g f i l e p r o c e s s i n g . A n y a d d i t i o n a l v o l u m e l a b e l s a r e i g n o r e d b y t a p e d a t a m a n a g e m e n t .
- - L a b e l e d T a p e
F i x e d o r v a r i a b l e - l e n g t h a n d b l o c k e d o r u n b l o c k e d d a t a records.
Symbol indicating the end of data records.
End-of-volume or end-of-f ile labels.
These two tape marks indicate the end of a volume. (There i s o n e t a p e m a r k i f t r a i l e r l a b e l s c o n t a i n e n d - o f - v o l u m e l a b e l s
N o n s t a n d a r d l a b e l s c o n t a i n w h a t e v e r i n f o r m a t i o n t h e u s e r d e s i r e s t o i n c l u d e . T h e s e l a b e l s m a y v a r y in l e n g t h a n d fo r - m a t a n d a r e th e c o m p l e t e r e s p o n s i b i l i t y o f t h e u s e r . N o n - standard labels are not checked by System/3 tape data m a n a g e m e n t f o r i n p u t f il e s , a n d th e y m a y n o t b e w r i t t e n f o r o u t p u t fi l e s . F o r E B C D I C i n p u t fi l e s w i t h n o n s t a n d a r d labels, the first record on the volume cannot be an 80-byte r e c o r d b e g i n n i n g w i t h V O L i ; f o r A S C I I in p u t f i l e s w i t h nonstandard labels, records cannot be greater than 80 bytes b e g i n n i n g w i t h V O L 1 .
B l a n k s p a c e a t t h e b e g i n n i n g o f a r e e l o f t a p e t h a t a l l o w s t h r e a d i n g t a p e t h r o u g h t h e f e e d m e c h a n i s m .
R e f le c t i v e m a r k e r th a t i n d i c a t e s t h e b e g i n n i n g o f t h e r e c o r d i n g a r e a .
F i r s t r e c o r d o n t a p e ( w r i t t e n b y t a p e i n i t i a l i z a t i o n , $ T l N l T ) t h a t i d e n t i f ie s th e r e e l .
l d e n t i f y t h e f i l e ( w r i t t e n b y t h e s y s t e m w h e n t h e d a t a w a s written) and always precede data records.
n d i c a t i n g t h e e n d o f t h e l a b e l g r o u p .
Ref lective marker that a r e e l .
Figure 1. Tape Formats:
i n d i c a t e s t h e e n d o f u s a b l e t a p e o n
Labeled Single or Multivolume Files
reco rd i ng F i r s t r e c o
I t h a t i d e n t
I
| - l d e n t i f y t
| |
w r i t t e n ) a
t t
| | s v m b o r i r
t t l
r r l
I ---t--- |
Leader -oad P o i n t
V o l u m e Label
H e a d e r L a b e l
'l
H e a d e r L a b e l
2
Tape
Mark Data
)
Tape M a r k
T r a i l e r L a b e l
1
T r a i l e r L a b e l
2
Tape M a r k ( T a p e M a r k
E n d of
R e e l
(
=--..._--// +
j l l l
r l
re
l e l s . )
T r a i l e r L a b e l
2
lVote; Two successive taoe marks indicate the end of the l a s t f i l e o n t h e r e e l u n l e s s t h e p r e v i o u s t r a i l e r l a b e l s a r e e n d - o f - v o l u m e ; i n w h i c h c a s e , o n l y o n e ta p e m a r k is p r e s e n t . R e f e r t o F i g u r e 1 f o r t e r m i n o l o g y d e f i n i t i o n s .
o Figure 2. Tape Formats: Labeled Multifile Volume
T r a i l e r L a b e l
1
T r a i l e r L a b e l
2
' Optional; if present, it is ignored.
N o t e : T w o t a p e m a r k s a r e w r i t t e n a t t h e e n d o f a s i n g l e v o l u m e f i l e . O t h e r v o l u m e s o f a m u l t i v o l u m e fi l e h a v e o n e t a p e m a r k a t o Figure 3. Unlabeled Single or Multivolume Files
f i l e a n d a t t h e e n d o f t h e t h e e n d . R e f e r to F i g u r e
l a s t v o l u m e o f a m u l t i v o l u m e 1 f o r t e r m i n o l o g y d e f in i t i o n s .
' Optional; if Present, it is ignored'
l V o t e ; T w o t a p e m a r k s in d i c a t e th e e n d o f t h e v o l u m e u n l e s s t h e l a s t fi l e o n t h e v o l u m e i s m u l t i v o l u m e f i l e , i n w h i c h c a s e , o n l y o n e r a p e m a r k i s p r e s e n t . R e f e r to F i g u r e 1 f o r t e r m i n o l o g y d e f in i t i o n s '
o Figure 4. Tape Formats: Unlabeled Multifile Volume
U s e r - s t a n d a r d l a b e l s a r e f i l e l a b e l s t h a t f o l l o w s t a n d a r d h e a d e r a n c l t r a i l e r l a b e l c o n v e n t i o n s ( A N S I o r I B M ) . T h e y a r e a v a r i a t i o n o f s t a n d a r d la b e l s w i t h a p a r t i a l l y f i x e d f o r - m a t . T h e s e la b e l s a r e s o m e t i m e s p r o v i d e d b y o t h e r s y s t e m s . U s e r - s t a n d a r d l a b e l s a r e n o t c h e c k e d b y S y s t e m / 3 ta p e data management and may not be written as part of the l a b e l g r o u p .
F i l e l a b e l s a r e w r i t t e n b e f o r e a n d a f t e r t h e l o g i c a l fi l e o n a r e e l . T h e s e la b e l s a r e r e f e r r e d t o a s fi l e h e a d e r la b e l s o r f i l e t r a i l e r l a b e l s , d e p e n d i n g o n t h e i r p o s i t i o n a n d u s e . H e a d e r l a b e l s p r e c e d e t h e d a t a f i l e . T r a i l e r la b e l s a r e e i t h e r e n d - o f - f i l e o r e n d - o f - v o l u m e . E n d - o f - f i l e t r a i l e r l a b e l s a r e w r t t t e n a t t h e e n d o f t h e l o g i c a l f i l e . E n d - o f - v o l u m e tr a i l e r l a b e l s a r e w r i t t e n a t t h e e n d o f a r e e l in d i c a t i n g t h a t t h e f i l e i s c o n t i n u e d o n a n o t h e r r e e l . T h e l a b e l fo r m a t s a r e s h o w n
in Appendix A, TaPe Label Formats.
M a g n t : t r c T a p e C o n c e P t s
T A P E R E C O R D A T T R I B U T E S
F : i l e s c o n s i s t o f a c o l l e c t i o n o f l o g i c a l re c o r d s . The logical r e c o r d is t h e b a s i c u n i t o f i n f o r m a t i o n for a program. The l o g i c a l re c o r d s a r e e i t h e r f i x e d o r v a r i a b l e le n g t h .
Frixed Length Records
F i x e d l e n g t h r e c o r d s h a v e a c o n s t a n t n u m b e r o f c h a r a c t e r s w i t h i n a r e c o r d . T h e r e c o r d s can be either blocked or u n b l o c k e d .
Variable Length Records
V a r i a b l e le n g t h r e c o r d s h a v e a different number of c h a r a c t e r s w i t h i n e a c h r e c o r d . T h e r e c o r d s can also be e i t h e r b l o c k e d o r u n b l o c k e d . T h e first four bytes of the l o g i c a l re c o r d c o n t a i n th e l e n g t h of that record. Variable I l e n g t h r e c o r d s c a n n o t b e u s e d w i t h t h e M o d e l 1 0 Card I System.
T A P E B L O C K I N G F A C T O R S
R e c o r d s t h a t a r e n o t g r o u p e d a r e u n b l o c k e d ; that is. each r e c o r d m a k e s u p a p h y s i c a l b l o c k . Blocking the records is t h e p r o c e s s o f c o m b i n i n g tw o o r m o r e l o g i c a l re c o r d s be_
f o r e t h e y a r e w r i t t e n o n t a p e . R e c o r d s are processed b y t h e s y s t e m in e i t h e r th e b l o c k e d o r unblocked format. The s y s t e m h a n c l l e s t h e b l o c k i n g a n d d e b l o c k i n g o f l o g i c a l r e c o r d s s o y o u n e e d to d e t e r m i n e o n l y t h e most eff icient b l o c k s i z e fo r t h e f i l e .
R r : c o r d s o r p h y s i c a l b l o c k s a r e s e p a r a t e d o n t a p e b y a n I B G ( i n t e r b l o c k g a p ) . T h e s y s t e m p r o d u c e s this gap during t a p e w r i t e o p e r a t i o n s .
Logical Unblocked Records
F t e t o c k * l
[*1 B toct*lf*1 atocr*l
L o g i c a I
R e c o r d I B G L o g i c a l
R e c o r d I B G L o g i c a I R e c o r d
Logical Blocked Records
[-i Btock---{
Log ica I R e c o r d
L o g i c a l R e c o r d
The number of logical records combined into one physical record or bloc* is the blocking factor. lf you specify an appropriate blocking factor for an application, many of the interblock gaps are eliminated, and the eff iciency of proc- e s s i n g i s im p r o v e d .
Blocking improves the effective processing speed by re- ducing the number of l/O operations required to process a file. For example, if 30 unblocked records were written on tape. 30 write operations would be required. By specifying a b l o c k i n g f a c t o r o f 1 0 , o n l y t h r e e w r i t e o p e r a t i o n s a r e required. The block length must be specified in multiples of the logical record length. Your selection of the block length is based on the amount of main storage available (greater tape efficiency is obtained with larger blocks) . Approximately 40,000 System/3 cards (20 boxes) punched in all 96 columns may be contained in 2400 feet of tape if t h e d a t a is w r i t t e n in t h e 1 6 0 0 b p i u n b l o c k e d f o r m a t . l f a blocking factor of 10 were specified, approximately 224,OOO c a r d s ( 1 1 2 b o x e s ) c o u l d b e s t o r e d o n t h e s a m e a m o u n t o f t a p e u s i n g t h e s a m e d e n s i t y .
TAPE CHARACTER CODES
T h e s y s t e m i s c a p a b l e o f h a n d l i n g t a p e d a t a fi l e s in o n e o f t w o c o d e s : E B C D I C ( e x t e n d e d b i n a r y c o d e d d e c i m a l i n t e r c h a n g e c o d e ) o r A S C I I ( A m e r i c a n N a t i o n a l S t a n d a r d C o d e f o r I n f o r m a t i o n I n t e r c h a n g e ) . T h e fo l l o w i n g l i s t s h o w s the tape formats supported by System/3 for the tape data files. (Variable length records are not supported by the Model 10 Card System.)
F i x e d le n g t h r e c o r d s : B l o c k e d o r u n b l o c k e d E B C D I C o r A S C I I c o d e V a r i a b l e l e n g t h r e c o r d s :
Btocked or unblocked E B C D I C c o d e (F o r m a t V ) A S C | l c o d e ( F o r m a t D )
Page of GC21 -5040-3 lssued 30 June 1978 B y T N L : G N 2 1 - 5 6 0 4 A S C I I F i l e s
A S C I I is a 7 - b i t c o d e c o n t a i n i n g 1 2 8 c h a r a c t e r s . A S C I I files are specif ied on a FILE control statement (see Control Statement Requirements). When translating ASCII files, an entire record is translated witfrout f ield differentiation' T h e in p u t fi l e s a r e tr a n s l a t e d t o E B C D I C f r o m A S C I I b y tape data management. and the output files are translated f r o m E B C D I C t o A S C I I b e f o r e b e i n g w r i t t e n . L a b e l s o n tape files which contain ASCII data must conform to the A N S I f o r m a t .
E B C D I C F i l e s
EBCDIC is an 8-bit code containing 256 characters. lf t h e r e is n o i n s t a l l a t i o n r e q u i r e m e n t f o r A S C I I d a t a in t e r - change, magnetic tape files should be recorded in EBCDIC;
EBCDIC is the natural code representation for the System/3 processing unit. The use of EBCDIC eliminates the object program overhead which results from the translation of A S C I I to E B C D I C .
Magnetic Tape Concepts 7
Chapter 3. Magnetic Tape System Support
System/3 program support provides input and output capa_
b i l i t y f o r d a t a s t o r a g e f i l e s . T h e F I L E statement. w h i c h d e f i n e s t h e ' t a p e f i l e , a n d th e tape utility programs a r e d e s c r i b e d i n t h i s c h a p t e r .
C O N T R O L S T A T E M E N T R E O U I R E M E N T S Model 10 Card System
lt '/Loc J +- | J { o r r {
= , j
T h e L O G c o n t r o l c a r d i n d i c a t e s w h e t h e r y o u w a n r t h e F I L E c a r d s a n d d i a g n o s t i c m e s s a g e s p r i n t e d . T h e f o r m a r ot the c a r c j i s i l l u s t r a t e d u s i n g th e c o n v e n t r o n s s h o w n i n F i g u r e 5 . l r t h e L O G c a r d i s n o t u s e d , the FILE cards, diagnostic r i e s s a g e s , a n r J R U N c a r d s w i l l b e p n n t e d a s i f L O G O N w a s s p e c r f i e c i . T h e L O G c o n t r o i c a r d p r e c e c i e s t h e F I L E re ro s.
\ , ' I F I L . E li s t o f p a r a m e r e r s
. \ F I L E c o n t r o l card contains information concernrng rne t a p e f i l e s . : / o u m u s t s u p p l y o n e F t L E c a r d f o r e a c n new t a p e t i l e c r e a t e d b y y o u r p r o g r a r n a n d t o r e a c h o f t h e t : x i s t i n g la p e f i l e t h a t V o u r D r o g r a m s u s e .
T h e p a r a m e t e r s t h a r a r e a i i o w e d o n t h e c o n t r g i c a r u { l r e s h o w n i n F r , ; u r e 6 . T h e x e v w o r d o a r a m e t e ! . s . n a v o e r r s t e d , f , n t h e c o n t r o t c a r d i n a n V o r d e r . G e n e r a l c o d r n r , ; r u i e s fo r the F I LE card are contarned in the iBM System,/3 Card Svstem tlper,etor s Guicte GC2l 7513
A R U N c o n t r o i c a r d m u s t f o l l o w t h e l a s r tr l L E c c n t r o l c a r d . T h i s c a r d s e r v e s r o d e t i m t t t h e e n d o f I h e c o n t r o i i:ard specifications anci requests that the tape program be executed. Vlodei i0 Card Svsler.rt control csrds are up.
ward cornpat.ible wrttr tn{ise Df 1.he itther SVstenr;'3 morlets
il/lodel 8, Model 10 Disk System, Model 12, and Model 15 A set of OCI- statements must be supplied for each program r u n . W i t h i n t h i s s e t o f s t a t e m e n t s i s t h e F I L E s t a r e m e n r w h i c h p r o v i d e s t h e s y s t e m w i t h i n f o r m a t i o n a b o u t the t a p e f i l e s . T h e f o r m a t s c f t h e s t a t e m e n t s a r e i l l u s t r a t e d u s i n g th e c o n v e n t i o n s s h o w n i n F i g u r e b .
Y o u r n u s t s u p p l y o n e F I L E s t a t e m e n t fo r each new raoe f i i e c r e a t e d b y y o u r p r o g r a m a n d f o r e a c h o f t h e exrslng t a p e f i l e s v o u r p r o g r a m u s e s . T h e p a r a m e t e r s a l l o w e c j o n i h e F I L E s t a t e m e n t a r e s h o w n i n F i g u r e 6 . The keyword p a r a m e t e r s m a y b e i i s t e d o n t h e F I L E s t a t e m e n t in a n v D r d e r .
t j e n e r a l c o c i i n g ru l e s fo r t h e F I L E statement are con{atnee
; n t h e S C F p u b l r c a t r o n s l i s t e t l in t h e P r e r a c e .
; , 1 F I L E i i s t o f p a r a m e t e r s
B R A C K E T S I I i n d i c a t e a n o p t i o n a l e n t r y .
P a g e o f G C 2 l - 5 0 4 0 - 3 l s s u e d 3 0 J u n e 1 9 7 8 B y T N L : G N 2 1 - 5 6 0 4
B R A C E { i
J I i n a i " u t . a c h o i c e o f e n t r i e s .
t - . , N D E R S C O R E i n a n o p t i o n a l e n t r v m e a n s th a t t h e i t n d e r s c o r e d v a l u e is a s s u m e d i f t h e e n t r v i s n o t p r e s e n t i n t h e s t a t e m e n r .
l l Y P H E l { S s e p a r a t e k e y w o r d s a n d p a r a m e t e r s . C O M M r \ S s e p a r a t e a i l e n t r r e s .
S P E C I A I - C H A R A C T E R S , s u c h a s l/ , m u s t a p p e a r a s th e y l ; r e s h o w n i n t h e s t a t e m e n t to r m a t . / 4 / O R D S O R A B B R E V I A T I O N S I N C A P I T A L L E T T E R S ,
s u c h a s B L K L a n d N L , m u s t a p p e a r a s s n o w n r n t n e s t a t e r n e n t t o r m a t . S M A L L L E T T E R S , s u c h a s v y y a n d m n , r e p r e s e n r i r u m -
i ) e r s o r o t h e r i n f o r m a t i o n y o u m u s t s u p p l y . T h e n u m b e r o f I e t t e r s in d i c a t e s t h e n u m b e r o f c h a r a c t e r s i n t h e i n f o r - r n a t i o n o r i h e n u r n b e r o f d i q i t s in t h e n u m b e r s . , r h r e e d o t s , a s in x . . . x ,
F i q u r e 5 . C o d i n g C o n v e n t i o n s fo r Control Statements
; d e v w o r d P a r a m e t e r s for the FILE Statement
i i n d i c a t e th a t t h e n u m b e r o f c h a r a c t e r s ;
I , i r d r g r t s n r a y v a r v . I
)i
t M o d " l 1 5 o n l y
F i g u r e 6 . K e y w o r d P a r a m e t e r s { o r t h e F I L E S t a t e m e n l
, _ r 1
i r r
\ r z
U N II T 3
I T n
r ' T n
i
I
N A T V i E - f i l e n a m e
, " ' \
iVAME is a required keyword paraffleter in the FiLE state-
; 1 e n t . i 1 . t p e c r f i e s t h e n a r n e V o u r p r o g r a m u s e s t o r e t e r t o : h e t a p e J i l e . T h e n a m e c a n L l e u p t o e i g h t c h a r a c t e r s i o n g . l , r e i i r s i c h a r a c t e r r n u s t b e i i p h a b e t i c , a n d t h e r e m a r n r n q i ; n a r a c t e r , : : i r : a n b e a i p h a m e r j c .
i J N I T i s a r e q u i r e d k e y w o r d p a r a m e t e r r n t h e F l t - E s t a t e - r n e n t . i t t e ! l s th e s v s t e m w h r c h t a p e u n i t s c o n t a I n th e f i l e . F o r a m u t t i v o i u m e ti i e , t h e u n t t s m u s i b e c o d e c I n r h e Jrder the files are to De processed, anct the pararneter rnust b e e n c l o s e d i n q u o t e s . O u o t e s a r e n o t r e q u i r e d tf o n l V o n e i a p e u n i t i s u s e d fo r a m u i t i v o l u m e fi l e "
i f v o u r f i l e r e s r d e s o n m o r e r e e l s t h a n y o u h a v e ta p e u n i t s . t h e t a p e u n i t s a r e u s e d a l t e r n a t e l y - F o r e x a m p l e , if t h e
\ v s t e m c o n f i q u r a t i o n n c l u d e s t w o t a p e u n i t s ( s p e c i f i e d b v - 1
a n o T ; r r n t h e U N I T p a r a m e t e r ) a n c i y o u r m u i t i v o l u r n e f i i e i s c o n r a r n e c j o n i h r e e v o i u m e s , t h e s y s t e m p r o c e s s e s r h e f i r s t ! . / g r u r n e o n l - 1 , i h e s e c o n c v o i u m e o n T 2 , a n d t h e : h i r d v o l u m e o n T l i
Parameters Model 10 Card SystemOther System/3
Models
R e q u i r e d I O p t i o n a l R e q u i r e d I O p t i o n a l N A M E
U N I T R E E L
I n p u t fi l e s O u t p u t fi l e s L A B E L D A T E R E T A I N B L K L R E C L R E C F M E N D D E N S I T Y A S C I I
X X
X
X
X X
;{
X
X X
X
X X
X X X
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Page of GC21-5040-3 lssued 30 June 1978 B y T N L : G N 2 1 - 5 6 0 4
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REEL is a required keyword parameter in the FILE state- m e n t fo r i n p u t f il e s a n d is o p t i o n a l f o r o u t p u t f il e s . lt s f u n c t i o n i s to i d e n t i f y t h e v o l u m e l a b e l o f t h e t a p e o n w h i c h th e f i l e r e s i d e s . T h e fo l l o w i n g d e s c r i b e s t h e n u m - bered parameter entries:
n T h i s e n t r y is u s e d f o r l a b e l e d v o l u m e s . A s i n g l e v o l - u m e fi l e i s id e n t i f i e d b y c o d i n g a m a x i m u m o f s i x c h a r a c t e r s n o t i n c l u d i n g t h e q u o t e , c o m m a , a n d b l a n k . This entry is used for labeled volumes. Each reel of a m u l t i v o l u m e f i l e m u s t b e i d e n t i f i e d s e p a r a t e l y . T h e reels are processed in the order they appear. Six char- a c t e r s , n o t i n c l u d i n g t h e q u o t e . c o m m a , a n d b l a n k , identify a reel. The entries specified must be enclosed i n o u o t e s .
T h e s p e c i f i c a t i o n N L ( n o t la b e l e d ) i s u s e d i f t h e f i l e resides on an unlabeled tape. The first record of an unlabeled tape must not be an 80-byte record begin- n i n g w i t h V O L 1 .
l f a m u l t i v o l u m e f i l e r e s i d e s o n u n l a b e l e d t a p e s , t h e n u m b e r o f u n l a b e l e d t a p e s t h a t c o n t a i n t h e f i l e i s s p e c i f i e d i n t h i s e n t r y . T h e d e f a u l t v a l u e f o r n i s 1 . T h e s p e c i f i c a t i o n N S ( n o n s t a n d a r d ) i n d i c a t e s a n i n p u t f i l e w i t h l a b e l s t h a t d o n o t a d h e r e t o t h e I B M Tape Label Standard. The first record of a non- standard labeled tape must not be an 80-byte record b e g i n n i n g w i t h V O L 1 .
l f a m u l t i v o l u m e i n p u t fi l e r e s i d e s o n t a p e s t h a t d o not adhere to the IBM Tape Label Standard, the number of tapes that contain the file is specif ied in t h i s e n t r y . T h e d e f a u l t v a l u e f o r n i s 1 .
A The specification BLP (bypass label processing) i n d i c a t e s t h a t t h e i n o u t f i l e r e s i d e s o n a s t a n d a r d labeled volume and label processing is to be bypassed.
R E E L - B L P i s n o t s u p p o r t e d o n t h e M o d e l 1 0 C a r d Svstem.
t r l f a m u l t i v o l u m e i n p u t fi l e r e s i d e s o n s t a n d a r d l a b e l e d t a p e s a n d la b e l p r o c e s s i n g i s b y p a s s e d , t h e n u m b e r o f l a b e l e d t a p e s t h a t c o n t a i n t h e f i l e is s p e c i f i e d i n t h i s e n t r v . T h e d e f a u l t v a l u e f o r n i s 1 . l f t h e R E E L k e y w o r d i s n o t u s e d f o r a n o u t p u t fi l e , th e n the system assumes a standard labeled tape is mounted.
M u l t i v o l u m e t a p e f i l e s c a n n o t b e s p e c i f i e d o n t h e M o d e l 8 , M o d e l 1 0 D i s k S y s t e m , o r M o d e l 1 2 fo r p r o g r a m s t h a t a l s o use the BSCA or devices attached to the SIOC.
a
L A B E L i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E statement. lt is used to specify the name (label) of the t a p e fi l e a s it e x i s t s i n t h e h e a d e r l a b e l . lf L A B E L is n o t specified, the system defaults to the NAME parameter u n l e s s R E E L - N S o r R E E L - N L i s a l s o s p e c i f i e d . L A B E L c a n n o t b e u s e d w h e n R E E L - B L P i s s o e c i f i e d .
The name entry must begin with one of the 29 alphabetic characters; the remaining characters must not be a quote, c o m m a . o r b l a n k . l f t h e n a m e o f t h e f i l e i n t h e h e a d e r label exceeds eight characters, only the first eight characters a r e u s e d .
A label may also be specified using special characters. The character string must be enclosed in quotes. cannot contain commas, and is restricted to eight characters in length.
LABEL.
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D A T E i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E statement. lt ensures that the proper input or output file is referenced by verifying the date in the file label (standard l a b e l s ) . D A T E c a n n o t b e u s e d w h e n R E E L - B L P i s s p e c i f i e d .
1 0
The date may be coded in one of two forms, month-day- y e a r (m m d d y y ) o r d a y - m o n t h - y e a r ( d d m m y y ) . The format rnust match the system date format chosen at s y s t e m g e n e r a t i o n t i m e ( e x c e p t M o d e l 1 0 C a r d S y s t e m ) . The system date is used as the creation date for output f i l e s . l t m a y b e c h a n g e d f o r a p r o g r a m b e i n g r u n o n t h e M o d e l 8 , M o d e l 1 0 D i s k S y s t e m , M o d e l 1 2 , o r M o d e l 1 5 by placing the OCL DATE statement after the LOAD state ment.
R E T A I N - n n n
R E T A I N i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E s t a t e m e n t ; i t i n d i c a t e s t h e n u m b e r o f d a y s a f i l e s h o u l d b e retained before it is scratched. The number may be from 0 to 999. Leading zeros are not required. After the number o f d a y s h a s e l a p s e d , t h e f i l e e x p i r e s , a n d t h e s y s t e m a l l o w s the file to be written over. The system assumes a value of zero when the parameter is omitted. The value of 99g is s p e c i f i e d t o c r e a t e a n o n e x p i r i n g p e r m a n e n t t a p e f i l e . l f a n a t t e m p t i s m a d e to w r i t e o v e r a n u n e x p i r e d fi l e , t h e system halts and allows the operator to cancel the iob or c o n t i n u e .
R E T A I N i s u s e d fo r s t a n d a r d la b e l e d fi l e s o n l V . R E T A I N c a n n o t b e u s e d if R E E L - B L P i s s p e c i f i e d .
B L K L - b l o c k le n o t h
B L K L i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E s t a t e m e n t ; i t i n d i c a t e s t h e n u m b e r o f b y t e s i n a p h y s i c a l b l o c k o f d a t a o n t a p e . T h e m i n i m u m s i z e , fi x e d l e n g t h b l o c k ( F B ) t h a t c a n b e s p e c i f i e d i s 1 8 b y t e s . V a r i a b l e l e n g t h ( V B o r D B ) b l o c k s a r e p a d d e d w i t h X ' 0 0 ' ( E B C D I C ) o r X ' 5 E ' ( A S C l l ) , w h e n n e c e s s a r y , t o m e e t t h e 1 8 - b y t e m i n i m u m b l o c k l e n g t h r e q u i r e m e n t . T h e m a x i m u m s i z e block that can be specified, regardless of record format, is 32,7 67 .
W h e n f i x e d b l o c k e d E B C D I C r e c o r d s a r e u s e d , th e b l o c k l e n g t h r n u s t b e a n i n t e g r a l m u l t i p l e o f t h e r e c o r d le n g t h . W h e n f i x e d b l o c k e d A S C I I r e c o r d s a r e u s e d . th e b l o c k l e n g t h r n u s t in c l u d e th e b u f f e r o f fs e t l e n g t h . W h e n t h e buffer offset length is subtracted from the block length, t h e r e m a i n d e r m u s t b e a n i n t e g r a l m u l t i p l e o f t h e r e c o r d l e n g t h . F o r a f i l e c o n t a i n i n g b l o c k e d E B C D I C v a r i a b l e l e n g t h ( V B ) r e c o r d s , t h e b l o c k l e n g t h m u s t i n c l u d e th e 4-byte block descriptor and the 4-byte record descriptor(s).
F o r b l o c k e d A S C I I v a r i a b l e l e n g t h ( D B ) r e c o r d s , t h e b u f f e r offset length and the 4-byte record descriptor(s) must be i n c l u d e d in t h e b l o c k l e n q t h .
Page of GC21 -5040-3 lssued 30 June 1978 B y T N L : G N 2 1 - 5 6 0 4 R ECL-record length
R E C L is a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E statement; it indicates the number of bytes in a logical tape record. The minimum record length permitted for f i x e d ( F ) o r f i x e d b l o c k e d r e c o r d s i s 1 8 b y t e s . U n b l o c k e d variable length (V or D) records are padded with X'00' ( E B C D I C ) o r X ' 5 E ' ( A S C I l ) , w h e n n e c e s s a r y , t o m e e t t h e 1 8 - b y t e m i n i m u m , b l o c k le n g t h r e q u i r e m e n t s . F o r f i l e s c o n t a i n i n g v a r i a b l e l e n g t h ( V or D) records, t h e r e c o r d length must include the 4-byte record descriptor.
R E C F M i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E statement; it identif ies the format of the input or output records. lt is not used with the Model 10 Card System.
The parameter entries are:
F - F i x e d l e n g t h , u n b l o c k e d r e c o r d s . L o g i c a l a n d physical records are the same length.
V - V a r i a b l e le n g t h , u n b l o c k e d r e c o r d s . E a c h p h y - sical record contains one logical record; the logical record can vary in length.
D - V a r i a b l e le n g t h , u n b l o c k e d r e c o r d s in t h e D - t y p e A S C l l f o r m a t .
F B - F i x e d l e n g t h , b l o c k e d r e c o r d s . A l l r e c o r d s a r e o f e q u a l l e n g t h a n d a l l b l o c k s a r e o f e q u a l l e n g t h . E a c h p h y s i c a l re c o r d c a n c o n t a i n m o r e t h a n o n e l o g i c a l re c o r d .
V B - V a r i a b l e le n g t h , b l o c k e d r e c o r d s . E a c h p h y s i c a l r e c o r d c o n t a i n s lo g i c a l re c o r d s o f v a r i o u s le n g t h s . D B - V a r i a b l e le n g t h , b l o c k e d r e c o r d s in t h e D - t y p e
A S C I I f o r m a t .
fuote.' U-type (unspecified) records are not supported.
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E N D i s a n r c p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E statement; its function is to control the position of the tape after tfre f ile has been processed. The tape remains i n i t s c u r r e n t p o s i t i o n if L E A V E i s s p e c i f i e d . lf UNLOAD i s s p e c i f i e d , t h e s y s t e m re w i n d s th e t a p e a n d p o s i t i o n s it f o r r e m o v a l fr o m t h e t a p e u n i t a t j o b termination time.
T h e t a p e i s r e w o u n d to t h e l o a d p o i n t i f the REWIND o p t i o n i s s p e c i f i e d . T h e s y s t e m a s s u m e s R E W I N D i f t h e END paramr-'ter is not specified.
D E N S I T Y i s a n o p t i o n a l p a r a m e t e r i n t h e F I L E s t a r e m e n t that is used to specify the number of bpi at which tape files are to be written or read. For 9-track tape, this parameter affects only the density of unlabeled output t a p e s a n d i s i g n o r e d fo r i n p u t t a p e s . W h e n s t a n d a r d - labeled or nonstandard labeled tapes are used, the 9-track t a p e h a r d w a n e a u t o m a t i c a l l y d e t e r m i n e s t h e d e n s i t y a t w h i c h t h e t a p e h a s b e e n in i t i a l i z e d . W h e n a f i l e i s initialized t o 1 6 0 0 b p i w i t h s t a n d a r d la b e l s , a n y f i l e t h a t i s w r i t t e n o n t h a t t a p e i s 1 6 0 0 b p i r e g a r d l e s s o f t h e D E N S I T y p a r a m e t e r . N o h a l t s o c c u r i f t h e w r o n g 9-track density is s p e c i f i e d .
The parameter entries are 800 or 1 600 bpi for 9-track tape.
a n d 2 0 0 , 5 5 6 , o r 8 0 0 b p i f o r 7 - t r a c k ta p e . l f t h e D E N S I T y p a r a m e t e r i s o m i t t e d , 1 6 0 0 b p i i s a s s u m e d f o r 9 - t r a c k t a p e a n d 8 0 0 b p i f o r 7 - t r a c k ta p e .
A S C I I i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E s t a t e m e n t ; i t i n f o r m s t h e s y s t e m w h e n a n A S C I I f i l e i s b e i n g u s e d . l f A S C I I f i l e s a r e b e i n g p r o c e s s e d , A S C I I - y E S m u s t b e s p e c i f i e d . A S C I I - Y E S i s i n v a l i d fo r 7 - t r a c k tape; if t h i s p a r a m e t e r i s o m i t t e d o r c o d e d A S C I I - N O . a n E B C D I C f ile is a ssu merd .
D E F E R i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E s t a t e m e n t . l t i s r e q u i r e d if t h e t a p e v o l u m e i s n o t o n l i n e at t h e b e g i n n i n g o f t h e j o b . l f t h i s p a r a m e t e r i s o m i t t e d . t h e s y s t e m a s s u m e s t h a t t h e t a p e v o l u m e i s o n l i n e .
D E F E R - Y E S c a n n o t b e s p e c i f i e d f o r p r o g r a m s o n t h e M o d e l 8 , M o d e l 1 0 D i s k S y s t e m , o r M o d e l 1 2 t h a t a l s o u s e B S C A o r d e v i c e s a t t a c h e d to t h e S I O C .
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C O N V E R T i s a n o p t i o n a l k e y w o r d p a r a m e t e r in t h e F I L E s t a t e m e n t . T h i s p a r a m e t e r i s v a l i d o n l y f o r 7 - t r a c k ta p e f i l e s . l t i n f o r m s th e s y s t e m th a t t h e d a t a c o n v e r t e r is o n or o f f . C O N V E R T - O N c a u s e s 7 - t r a c k d a t a t o b e p r o c e s s e d i n 8 - b i t b i n a r y f o r m . T h e c o n v e r t e r w r i t e s t h r e e m a i n s t o r a g e characters as four tape characters and converts the opposite w a y w h e n r e a d i n g . l f t h i s p a r a m e t e r i s o m i t t e d , C O N V E R T O F F i s a s s u m e d . W h e n p r o c e s s i n g v a r i a b l e l e n g t h r e c o r d s o n 7 - t r a c k ta p e f i l e s , C O N V E R T O N i s r e o u i r e d
T R A N S L A f E i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E s t a t e m e n t . T h i s p a r a m e t e r i s v a l i d o n l y f o r 7 - t r a c k t a p e f i l e s . l t i n f o r m s t h e s v s t e m th a t t h e d a t a t r a n s l a t o r is o n o r o f f . T R A N S L A T E - O N c a u s e s 7 - t r a c k d a t a t o b e p r o c e s s e d i n s i x - b i t B C D f o r m . T h e t r a n s l a t o r w r i t e s 8 b i t E B C D I C m a i n s t o r a g e c h a r a c t e r s a s 6 - b i t B C D t a p e c h a r a c t e r s a n d t r a n s l a t e s t h e o p p o s i t e w a y w h e n r e a d i n g . l f t h i s p a r a m e t e r i s o m i t t e d , T R A N S L A T E - O F F i s a s s u m e d . N o t e : l f C O N V E R T O F F a n d T R A N S L A T E - O F F a r e s p e c i f i e d , o n l y t h e s i x l o w - o r d e r b i t s o f t h e m a i n s t o r a g e c h a r a c t e r a r e w r i t t e n o n t h e t a p e . W h e n r e a d i n g w i t h C O N V E R T O F F a n d T R A N S L A T E - O F F , t h e t w o h i s h - o r d e r b i t s o f t h e m a i n s t o r a g e c h a r a c t e r s a r e s e t t o z e r o s .
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P A R I T Y is a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E s t a t e m e n t . T h i s p a r a m e t e r i s v a l i d o n l y f o r 7 - t r a c k t a p e files. lt is used to specify the parity at which tape characters w i l l b e p r o c e s s e d . l f t h i s p a r a m e t e r i s o m i t t e d , P A R I T Y - O D D i s a s s u m e d .
N o t e : C e r t a i n c o m b i n a t i o n s o f C O N V E R T , T R A N S L A T E , a n d P A R I T Y a r e in v a l i d .
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Page of GC21-5040-3 l s s u e d 3 0 J u n e 1 9 7 8 B y T N L : G N 2 1 - 5 6 0 4 which does not contain a DEFER parameter, is expected t o b e o n l i n e a t t h e b e g i n n i n g o f t h e e x e c u t i o n o f t h e p r o g r a m . W h e n a n e w fi l e i s b e i n g w r i t t e n . t a p e d a t a m a n a g e m e n t c h e c k s f o r a n e x i s t i n g f i l e ( i f i t h a s s t a n d a r d l a b e l s ) t o e n s u r e t h a t a n u n e x p i r e d f i l e i s n o t d e s t r o y e d . Tape data management provides support for sequential processing of tape files. The two logical access methods are consecutive input and consecutive output. Consecutive input retrieves records from a sequential f ile with records o b t a i n e d f r o m c o n t i g u o u s l o c a t i o n s b e g i n n i n g w i t h t h e first record. Consecutive output writes the records s e q u e n t i a l l y o n t a p e b u i l d i n g a t a p e fi l e b e g i n n i n g w i t h t h e fi rst record .
End of Volume Processing
The end-of-reel ref lective marker indicates the end of tape w h e n a f i l e i s w r i t t e n . W h e n t h e m a r k e r i s d e t e c t e d , t a p e d a t a m a n a g e m e n t w r i t e s a t a p e m a r k . T r a i l e r l a b e l s ( E O V , e n d - o f - v o l u m e ) a r e w r i t t e n if t h e f i l e i s a l a b e l e d f i l e . T a p e data management then issues a rewind/unload command to t h e t a p e u n i t . T h e n e x t ta p e v o l u m e , a s s p e c i f i e d o n t h e F IL E s t a t e m e n t , i s th e n o p e n e d , h e a d e r l a b e l s a r e w r i t t e n f o r a l a b e l e d f i l e , a n d d a t a m a n a g e m e n t c o n t i n u e s t o w r i t e th e f i l e . W h e n t h e la s t v o l u m e o f t h e o u t p u t f i l e h a s b e e n w r i t t e n . d a t a m a n a g e m e n t w r i t e s t r a i l e r l a b e l s ( e n d - o f - f i l e ) f o r a l a b e l e d f i l e a n d is s u e s t h e o p t i o n a l r e w i n d / u n l o a d c o m m a n d ( E N D p a r a m e t e r o n t h e F I L E s t a t e m e n t ) t o t h e l a s t t a p e u n i t .
W h e n r e a d i n g a n i n p u t f i l e , re c o g n i t i o n o f a t a p e m a r k i n d i c a t e s a n e n d c o n d i t i o n . T r a i l e r l a b e l s a r e re a d a n d c h e c k e d i f t h e t a p e fi l e is la b e l e d . F o r a m u l t i v o l u m e t a p e f i l e , th e n e x t v o l u m e i s o p e n e d a s s p e c i f i e d o n t h e F I L E statement.
Dual Programming {Models 8, 10, and 12) or Multi- programming (Model 15)
You can address separate tape units from any program level (partition) on these systems; however, a tape unit cannot be in use by two program levels (partitions) s i m u l t a n e o u s l y , R e q u i r e d t a p e u n i t s a r e a l l o c a t e d t o t h e program by the system to ensure that two program levels (partitions) are not using the same unit.
F o r t h e M o d e l 8 o r t h e M o d e l 1 0 D i s k S y s t e m , a p r o c e s s i n g u n i t w i t h a m i n i m u m o f 1 6 K m a i n s t o r a g e i s r e q u i r e d t o support a tape environment in a dual programming system.
S E O N U M i s a n o p t i o n a l k e y w o r d p a r a m e t e r i n t h e F I L E s t a t e m e n t . l t i s u s e d o n l y o n t h e M o d e l 1 5 t o p o s i t i o n a f i l e i n a m u l t i f i l e v o l u m e f o r p r o c e s s i n g . l t c a n a l s o b e u s e d t o indicate that tape positioning is not required.
l f S E O N U M - n u m b e r i s u s e d w i t h R E E L - B L P , t h e s y s t e m searches the taoe for a standard label HDR 1 record con- t a i n i n g t h e f i l e n u m b e r . W h e n t h e r e c o r d i s f o u n d , fu r t h e r processing of the label group is terminated. The system then positions the tape to the file data. See the system c o n t r o l p r o g r a m m i n g r e f e r e n c e m a n u a l f o r M o d e l 1 5 listed in the Preface for additional information on m u l t i f i l e t a p e v o l u m e s .
T A P E D A T A M A N A G E M E N T
IBM System/3 tape management routines regulate the use of the magnetic tape units. The tape data management routines are included in the object program when your source programs are compiled.
Tape data management performs initial setup and label c h e c k i n g b e f o r e t h e f i l e i s o p e n e d . lt d e t e r m i n e s i f t h e f i l e is o n l i n e . E a c h f i l e , d e s c r i b e d b y t h e F I L E s t a t e m e n t ,
Magnetic Tape System SuPPort 1 3
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M A G N E T I C T A P E U T I L I T Y P R O G R A M S
F o u r c a r d - r e s i d e n t s u p p o r t p r o g r a m s a r e a v a i l a b l e f o r t a p e o n t h e M o d e l 1 0 C a r d S y s t e m :
o The Magnetic Tape Error Logout program punches the contents of counters accumulated during the execution of any Model 10 Card System program that updates the m a g n e t i c t a p e e r r o r c o u n t e r s .
o T h e M a g n e t i c T a p e E r r o r S u m m a r y p r o g r a m p r i n t s a report of the error statistics using the cards punched by t h e M a g n e t i c T a p e E r r o r L o g o u t p r o g r a m a s in p u t . o The Tape Dump program lists blocks of tape data on
t h e p r i n t e r i n b o t h h e x a d e c i m a l a n d c h a r a c t e r r e p r e s e n - t a t i o n u n t i l a t a p e m a r k is r e a d . T h i s p r o g r a m a l s o spaces a tape block backward or forward and rewinds a t a p e to t h e l o a d p o i n t .
o T h e T a p e Initialization p r o g r a m c r e a t e s I B M S t a n d a r d o r A N S I ta p e v o l u m e l a b e l s , c h e c k s f o r u n e x p i r e d f i l e s , a n d d i s p l a y s e x i s t i n g v o l u m e a n d fi l e l a b e l s . T h e T a p e I n i t i a l i z a t i o n p r o g r a m i s d e s c r i b e d i n t h e fo l l o w i n g s e c t i o n . ( T h i s p r o g r a m i s a l s o a v a i l a b l e f o r t h e o t h e r System/3 models.
I n a d d i t i o n t o t h e T a p e ln i t i a l i z a t i o n p r o g r a m ( p r e v i o u s l y m e n t i o n e d a n d d e s c r i b e d i n t h e f o l l o w i n g s e c t i o n ) , t h e Tape Volume Error Summary program is available for tape o n t h e M o d e l 8 . M o d e l 1 0 D i s k S y s t e m , M o d e l 1 2 . a n d M o d e l 1 5 . T h e T a p e V o l u m e E r r o r Summary p r o g r a m prints a report of statistics that have been accumulated d u r i n g p r o c e s s i n g a n d s t o r e d o n F 1 .
T A P E IN I T I A L I Z A T I O N P R O G R A M
The Tape lrritialization program prepares tapes for use. lt w r i t e s IB M s t a n d a r d v o l u m e l a b e l s o n t a p e a l l o w i n g t a p e data management to perform IBM standard laber process- i n g .
T h e T a p e In i t i a l i z a t i o n p r o g r a m c a n p e r f o r m t h e s e functions at your request:
CHECK labeled tapes for a volume label and an unex- p i r e d f il e b e f o r e w r i t i n g a n e w v o l u m e l a b e l .
C L E A R la b e l e d o r u n l a b e l e d t a p e s b y b y p a s s i n g C H E C K a n d u n c o n d i t i o n a l l y i n i t i a l i z i n g t h e t a p e .
. D I S P L A ' Y t h e v o l u m e a n d h e a d e r l a b e l s .
/Vofe.' DISPLAY causes tape runaway if it is performed on a tape that has never been initialized or if it is performed on a t a p e t h a t h a s n o t b e e n i n i t i a l i z e d s i n c e i t s la s t c l e a n i n g .
A l l t a p e s m u s t b e i n i t i a l i z e d b e f o r e u s e . T a p e s th a t h a v e b e e n in i t i a l i z e d n e e d n o t b e r e i n i t i a l i z e d u n l e s s y o u w a n t a n e w v o l u m e l a b e l w r i t t e n . T h i s p r o g r a m c a n e i t h e r i n i t i a l i z e ( C L E A R o r C H E C K ) o r D I S P L A Y o n e t a p e p e r u n i t d u r i n g the same program run.
Control Statements
T h e c o n t r o l s t a t e m e n t s y o u s u p p l y f o r t h e T a p e I n i t i a l i z a - t i o n p r o g r a m d e p e n d o n t h e t y p e o f i n i t i a l i z a t i o n a n d t h e n u m b e r o f t a p e s in i t i a l i z e d . F i g u r e 7 s h o w s th e s t a t e m e n t s r e q u i r e d b y t h i s u t i l i t y p r o g r a m to i n i t i a l i z e a r e e l o f t a p e o r d i s p l a y v o l u m e a n d h e a d e r la b e l s .
Control statements for the Model 10 Card System are read f r o m t h e p r i m a r y h o p p e r o f t h e M F C U . l f t h e s y s t e m finds an error in a control statement, you may correct the e r r o r a n d c o n t i n u e th e j o b o r t h e j o b c a n b e c a n c e l e d . The system requires a set of OCL statements to run the d i s k r e s i d e n t T a p e I n i t i a l i z a t i o n p r o g r a m . T h e t w o s t a t e - m e n t s th a t m u s t b e s u p p l i e d fo r t h i s u t i l i t y p r o g r a m a r e LOAD and RUN. These statements are part of the standard System/3 OCL statements as explained in the system control programming reference manuals listed in the preface.
The LOAD statement identif ies the program to be run. lt is the first of the required statements. The program name f o r t h e T a p e I n i t i a l i z a t i o n p r o g r a m is $ T l N l T . T h e u n i t parameter contains a code that indicates the location of the d i s k p a c k c o n t a i n i n g t h e T a p e I n i t i a l i z a t i o n p r o g r a m . T h e c o d e s a r e F 1 , R 1 , F 2 , a n d R 2 .
The program is loaded after the system reads the RUN statement. lf the control statements are read from the s y s t e m in p u t d e v i c e a n d a n e r r o r i s f o u n d , y o u m a y c o r r e c t t h e e r r o r a n d c o n t i n u e th e j o b , o r y o u m a y c a n c e l th e j o b . 1 4
When the control statements are read from a procedure on UNIT parameter informs the system which tape unit
d i s k a n d a n e r r o r is fo u n d , th e iob must be canceled. T h e c o n t a i n s t h e t a p e to b e i n i t i a l i z e d o r d i s p l a y e d . A s e p a r a t e END statement is required for every program and follows VOL statement is required for each tape unit that contains the last of the VOL statements. The program begins a tape to bi initialized or displayed.
i n i t i a l i z a t i o n o r d i s p l a y o f t h e t a p e a f t e r th e s y s t e m r e a o s t h e E N D s t a t e m e n t .
REEL parameter specifies either initialization of an un- l a b e l e d t a p e (N L ) o r t h e v o l u m e s e r i a l n u m b e r w h i c h th e
VOL Statemen f program writes on the tape (xxxxxx). This optional
p a r a m e t e r i s n o t n e e d e d i f T Y P E - D I S P L A Y i s s p e c i f i e d . N S T h e T a p e In i t i a l i z a t i o n p r o g r a m r e q u i r e s o n e o r m o r e c a n n o t b e s p e c i f i e d .
utility control statements (l/ VOLI . These statements s u p p l y i n f o r m a t i o n n e e d e d t o i n i t i a l i z e o r d i s p l a y a r e e l o f tape. The format of the VOL statement is shown in F i g u r e 7 . A m a x i m u m o f f o u r o f t h e s e s t a t e m e n t s m a y a p p e a r i n t h e jo b s t r e a m .
F i g u r e 7 . S p e c i f i c a t i o n s f o r t h e T a p e I n i t i a l i z a t i o n P r o g r a m
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Note: A separate VOL statement is required
/ / E N D
tVote.' These statements are not
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, T Y P E . < C L E A R ( c H e c <
f o r e a c h t a p e d r i v e u n i t c o n t a i n i n g a t a p e to b e i n i t i a l i z e d o r d i s p l a y e d . used with the Model 10 Card System.
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Magnetic Tape System Support 15
